mem_cgroup_calculate_protection() is not stateless and should only be used
as part of a top-down tree traversal. shrink_one() traverses the per-node
memcg LRU instead of the root_mem_cgroup tree, and therefore it should not
call mem_cgroup_calculate_protection().
The existing misuse in shrink_one() can cause ineffective protection of
sub-trees that are grandchildren of root_mem_cgroup. Fix it by reusing
lru_gen_age_node(), which already traverses the root_mem_cgroup tree, to
calculate the protection.
Previously lru_gen_age_node() opportunistically skips the first pass,
i.e., when scan_control->priority is DEF_PRIORITY. On the second pass,
lruvec_is_sizable() uses appropriate scan_control->priority, set by
set_initial_priority() from lru_gen_shrink_node(), to decide whether a
memcg is too small to reclaim from.
Now lru_gen_age_node() unconditionally traverses the root_mem_cgroup tree.
So it should call set_initial_priority() upfront, to make sure
lruvec_is_sizable() uses appropriate scan_control->priority on the first
pass. Otherwise, lruvec_is_reclaimable() can return false negatives and
result in premature OOM kills when min_ttl_ms is used.
It's because hugetlb folio is passed to __folio_undo_large_rmappable()
unexpectedly. large_rmappable flag is imperceptibly set to hugetlb folio
since commit f6a8dd98a2ce ("hugetlb: convert alloc_buddy_hugetlb_folio to
use a folio"). Then commit be9581ea8c05 ("mm: fix crashes from deferred
split racing folio migration") makes folio_migrate_mapping() call
folio_undo_large_rmappable() triggering the bug. Fix this issue by
clearing large_rmappable flag for hugetlb folios. They don't need that
flag set anyway.
Link: https://lkml.kernel.org/r/20240709120433.4136700-1-linmiaohe@huawei.com Fixes: f6a8dd98a2ce ("hugetlb: convert alloc_buddy_hugetlb_folio to use a folio") Fixes: be9581ea8c05 ("mm: fix crashes from deferred split racing folio migration") Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Lockdep considers this an AA deadlock because the different resize_lock
mutexes reside in the same lockdep class, but this is a false positive.
Place them in distinct classes to avoid these warnings.
Link: https://lkml.kernel.org/r/20240712031314.2570452-1-linmiaohe@huawei.com Fixes: 8531fc6f52f5 ("hugetlb: add hugetlb demote page support") Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Muchun Song <muchun.song@linux.dev> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/gup: clear the LRU flag of a page before adding to LRU batch
If a large number of CMA memory are configured in system (for example,
the CMA memory accounts for 50% of the system memory), starting a
virtual virtual machine with device passthrough, it will call
pin_user_pages_remote(..., FOLL_LONGTERM, ...) to pin memory. Normally
if a page is present and in CMA area, pin_user_pages_remote() will
migrate the page from CMA area to non-CMA area because of FOLL_LONGTERM
flag. But the current code will cause the migration failure due to
unexpected page refcounts, and eventually cause the virtual machine
fail to start.
If a page is added in LRU batch, its refcount increases one, remove the
page from LRU batch decreases one. Page migration requires the page is
not referenced by others except page mapping. Before migrating a page,
we should try to drain the page from LRU batch in case the page is in
it, however, folio_test_lru() is not sufficient to tell whether the
page is in LRU batch or not, if the page is in LRU batch, the migration
will fail.
To solve the problem above, we modify the logic of adding to LRU batch.
Before adding a page to LRU batch, we clear the LRU flag of the page
so that we can check whether the page is in LRU batch by
folio_test_lru(page). It's quite valuable, because likely we don't
want to blindly drain the LRU batch simply because there is some
unexpected reference on a page, as described above.
This change makes the LRU flag of a page invisible for longer, which
may impact some programs. For example, as long as a page is on a LRU
batch, we cannot isolate it, and we cannot check if it's an LRU page.
Further, a page can now only be on exactly one LRU batch. This doesn't
seem to matter much, because a new page is allocated from buddy and
added to the lru batch, or be isolated, it's LRU flag may also be
invisible for a long time.
mm/numa_balancing: teach mpol_to_str about the balancing mode
Since balancing mode was added in bda420b98505 ("numa balancing: migrate
on fault among multiple bound nodes"), it was possible to set this mode
but it wouldn't be shown in /proc/<pid>/numa_maps since there was no
support for it in the mpol_to_str() helper.
Furthermore, because the balancing mode sets the MPOL_F_MORON flag, it
would be displayed as 'default' due a workaround introduced a few years
earlier in 8790c71a18e5 ("mm/mempolicy.c: fix mempolicy printing in
numa_maps").
To tidy this up we implement two changes:
Replace the MPOL_F_MORON check by pointer comparison against the
preferred_node_policy array. By doing this we generalise the current
special casing and replace the incorrect 'default' with the correct 'bind'
for the mode.
Secondly, we add a string representation and corresponding handling for
the MPOL_F_NUMA_BALANCING flag.
With the two changes together we start showing the balancing flag when it
is set and therefore complete the fix.
Representation format chosen is to separate multiple flags with vertical
bars, following what existed long time ago in kernel 2.6.25. But as
between then and now there wasn't a way to display multiple flags, this
patch does not change the format in practice.
Roman Gushchin [Fri, 12 Jul 2024 18:35:14 +0000 (18:35 +0000)]
mm: memcg1: convert charge move flags to unsigned long long
Currently MOVE_ANON and MOVE_FILE flags are defined as integers
and it leads to the following Smatch static checker warning:
mm/memcontrol-v1.c:609 mem_cgroup_move_charge_write()
warn: was expecting a 64 bit value instead of '~(1 | 2)'
Fix this be redefining them as unsigned long long.
Even though the issue allows to set high 32 bits of mc.flags
to an arbitrary number, these bits are never used, so it doesn't
have any significant consequences.
Link: https://lkml.kernel.org/r/ZpF8Q9zBsIY7d2P9@google.com Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Reported-by: Dan Carpenter <dan.carpenter@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
alloc_tag: fix page_ext_get/page_ext_put sequence during page splitting
pgalloc_tag_sub() might call page_ext_put() using a page different from
the one used in page_ext_get() call. This does not pose an issue since
page_ext_put() ignores this parameter as long as it's non-NULL but
technically this is wrong. Fix it by storing the original page used in
page_ext_get() and passing it to page_ext_put().
Link: https://lkml.kernel.org/r/20240711220457.1751071-3-surenb@google.com Fixes: be25d1d4e822 ("mm: create new codetag references during page splitting") Signed-off-by: Suren Baghdasaryan <surenb@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Sourav Panda <souravpanda@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
set_initial_priority() tries to jump-start global reclaim by estimating
the priority based on cold/hot LRU pages. The estimation does not account
for shrinker objects, and it cannot do so because their sizes can be in
different units other than page.
If shrinker objects are the majority, e.g., on TrueNAS SCALE 24.04.0 where
ZFS ARC can use almost all system memory, set_initial_priority() can
vastly underestimate how much memory ARC shrinker can evict and assign
extreme low values to scan_control->priority, resulting in overshoots of
shrinker objects.
To reproduce the problem, using TrueNAS SCALE 24.04.0 with 32GB DRAM, a
test ZFS pool and the following commands:
for ((i = 0; i < 20; i++))
do
sleep 120
fio --name=mglru.anon --numjobs=16 --ioengine=mmap \
--filename=/dev/zero --size=1024m --fadvise_hint=0 \
--rw=randrw --random_distribution=random \
--time_based --runtime=1m
done
To fix the problem:
1. Cap scan_control->priority at or above DEF_PRIORITY/2, to prevent
the jump-start from being overly aggressive.
2. Account for the progress from mm_account_reclaimed_pages(), to
prevent kswapd_shrink_node() from raising the priority
unnecessarily.
mm/mglru: fix div-by-zero in vmpressure_calc_level()
evict_folios() uses a second pass to reclaim folios that have gone through
page writeback and become clean before it finishes the first pass, since
folio_rotate_reclaimable() cannot handle those folios due to the
isolation.
The second pass tries to avoid potential double counting by deducting
scan_control->nr_scanned. However, this can result in underflow of
nr_scanned, under a condition where shrink_folio_list() does not increment
nr_scanned, i.e., when folio_trylock() fails.
The underflow can cause the divisor, i.e., scale=scanned+reclaimed in
vmpressure_calc_level(), to become zero, resulting in the following crash:
[exception RIP: vmpressure_work_fn+101]
process_one_work at ffffffffa3313f2b
Since scan_control->nr_scanned has no established semantics, the potential
double counting has minimal risks. Therefore, fix the problem by not
deducting scan_control->nr_scanned in evict_folios().
Link: https://lkml.kernel.org/r/20240711191957.939105-1-yuzhao@google.com Fixes: 359a5e1416ca ("mm: multi-gen LRU: retry folios written back while isolated") Reported-by: Wei Xu <weixugc@google.com> Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Alexander Motin <mav@ixsystems.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm, page_alloc: put should_fail_alloc_page() back behing CONFIG_FAIL_PAGE_ALLOC
This mostly reverts commit af3b854492f3 ("mm/page_alloc.c: allow error
injection"). The commit made should_fail_alloc_page() a noinline function
that's always called from the page allocation hotpath, even if it's empty
because CONFIG_FAIL_PAGE_ALLOC is not enabled, and there is no option to
disable it and prevent the associated function call overhead.
As with the preceding patch "mm, slab: put should_failslab back behind
CONFIG_SHOULD_FAILSLAB" and for the same reasons, put the
should_fail_alloc_page() back behind the config option. When enabled, the
ALLOW_ERROR_INJECTION and BTF_ID records are preserved so it's not a
complete revert.
Link: https://lkml.kernel.org/r/20240711-b4-fault-injection-reverts-v1-2-9e2651945d68@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Akinobu Mita <akinobu.mita@gmail.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David Rientjes <rientjes@google.com> Cc: Eduard Zingerman <eddyz87@gmail.com> Cc: Hao Luo <haoluo@google.com> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: John Fastabend <john.fastabend@gmail.com> Cc: KP Singh <kpsingh@kernel.org> Cc: Martin KaFai Lau <martin.lau@linux.dev> Cc: Mateusz Guzik <mjguzik@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Song Liu <song@kernel.org> Cc: Stanislav Fomichev <sdf@fomichev.me> Cc: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm, slab: put should_failslab() back behind CONFIG_SHOULD_FAILSLAB
Patch series "revert unconditional slab and page allocator fault injection
calls".
These two patches largely revert commits that added function call overhead
into slab and page allocation hotpaths and that cannot be currently
disabled even though related CONFIG_ options do exist.
A much more involved solution that can keep the callsites always existing
but hidden behind a static key if unused, is possible [1] and can be
pursued by anyone who believes it's necessary. Meanwhile the fact the
should_failslab() error injection is already not functional on kernels
built with current gcc without anyone noticing [2], and lukewarm response
to [1] suggests the need is not there. I believe it will be more fair to
have the state after this series as a baseline for possible further
optimisation, instead of the unconditional overhead.
For example a possible compromise for anyone who's fine with an empty
function call overhead but not the full CONFIG_FAILSLAB /
CONFIG_FAIL_PAGE_ALLOC overhead is to reuse patch 1 from [1] but insert a
static key check only inside should_failslab() and
should_fail_alloc_page() before performing the more expensive checks.
This mostly reverts commit 4f6923fbb352 ("mm: make should_failslab always
available for fault injection"). The commit made should_failslab() a
noinline function that's always called from the slab allocation hotpath,
even if it's empty because CONFIG_SHOULD_FAILSLAB is not enabled, and
there is no option to disable that call. This is visible in profiles and
the function call overhead can be noticeable especially with cpu
mitigations.
Meanwhile the bpftrace program example in the commit silently does not
work without CONFIG_SHOULD_FAILSLAB anyway with a recent gcc, because the
empty function gets a .constprop clone that is actually being called
(uselessly) from the slab hotpath, while the error injection is hooked to
the original function that's not being called at all [1].
Thus put the whole should_failslab() function back behind
CONFIG_SHOULD_FAILSLAB. It's not a complete revert of 4f6923fbb352 - the
int return type that returns -ENOMEM on failure is preserved, as well
ALLOW_ERROR_INJECTION annotation. The BTF_ID() record that was meanwhile
added is also guarded by CONFIG_SHOULD_FAILSLAB.
Donet Tom [Wed, 10 Jul 2024 05:19:12 +0000 (00:19 -0500)]
hugetlbfs: ensure generic_hugetlb_get_unmapped_area() returns higher address than mmap_min_addr
generic_hugetlb_get_unmapped_area() was returning an address less than
mmap_min_addr if the mmap argument addr, after alignment, was less than
mmap_min_addr, causing mmap to fail.
This is because current generic_hugetlb_get_unmapped_area() code does not
take into account mmap_min_addr.
This patch ensures that generic_hugetlb_get_unmapped_area() always returns
an address that is greater than mmap_min_addr. Additionally, similar to
generic_get_unmapped_area(), vm_end_gap() checks are included to maintain
stack gap.
Ryan Roberts [Wed, 10 Jul 2024 09:55:01 +0000 (10:55 +0100)]
mm: shmem: rename mTHP shmem counters
The legacy PMD-sized THP counters at /proc/vmstat include thp_file_alloc,
thp_file_fallback and thp_file_fallback_charge, which rather confusingly
refer to shmem THP and do not include any other types of file pages. This
is inconsistent since in most other places in the kernel, THP counters are
explicitly separated for anon, shmem and file flavours. However, we are
stuck with it since it constitutes a user ABI.
Recently, commit 66f44583f9b6 ("mm: shmem: add mTHP counters for anonymous
shmem") added equivalent mTHP stats for shmem, keeping the same "file_"
prefix in the names. But in future, we may want to add extra stats to
cover actual file pages, at which point, it would all become very
confusing.
So let's take the opportunity to rename these new counters "shmem_" before
the change makes it upstream and the ABI becomes immutable. While we are
at it, let's improve the documentation for the legacy counters to make it
clear that they count shmem pages only.
Link: https://lkml.kernel.org/r/20240710095503.3193901-1-ryan.roberts@arm.com Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Lance Yang <ioworker0@gmail.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Reviewed-by: Barry Song <baohua@kernel.org> Acked-by: David Hildenbrand <david@redhat.com> Cc: Daniel Gomez <da.gomez@samsung.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Peter Xu [Mon, 8 Jul 2024 21:55:37 +0000 (17:55 -0400)]
mm/migrate: putback split folios when numa hint migration fails
This issue is not from any report yet, but by code observation only.
This is yet another fix besides Hugh's patch [1] but on relevant code
path, where eager split of folio can happen if the folio is already on
deferred list during a folio migration.
Here the issue is NUMA path (migrate_misplaced_folio()) may start to
encounter such folio split now even with MR_NUMA_MISPLACED hint applied.
Then when migrate_pages() didn't migrate all the folios, it's possible the
split small folios be put onto the list instead of the original folio.
Then putting back only the head page won't be enough.
Fix it by putting back all the folios on the list.
[akpm@linux-foundation.org: remove now unused local `nr_pages'] Link: https://lkml.kernel.org/r/20240708215537.2630610-1-peterx@redhat.com Fixes: 7262f208ca68 ("mm/migrate: split source folio if it is on deferred split list") Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Yang Shi <shy828301@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Huang Ying <ying.huang@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The page cannot become compound pages again just after a folio is split as
an extra refcnt is held. So the MF_MSG_DIFFERENT_COMPOUND case is
obsolete and can be removed to get rid of this false assumption and code
burden. But add one WARN_ON() here to keep the situation clear.
Link: https://lkml.kernel.org/r/20240708030544.196919-1-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Borislav Petkov (AMD) <bp@alien8.de> Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Now that folio_undo_large_rmappable() is an inline function checking
order and large_rmappable for itself (and __folio_undo_large_rmappable()
is now declared even when CONFIG_TRANASPARENT_HUGEPAGE is off) there is
no need for folio_migrate_mapping() to check large and large_rmappable
first (in the mapping case when it has had to freeze anyway).
Link: https://lkml.kernel.org/r/68feee73-050e-8e98-7a3a-abf78738d92c@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Barry Song <baohua@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Bang Li [Fri, 5 Jul 2024 03:23:09 +0000 (11:23 +0800)]
mm: thp: support "THPeligible" semantics for mTHP with anonymous shmem
After the commit 7fb1b252afb5 ("mm: shmem: add mTHP support for anonymous
shmem"), we can configure different policies through the multi-size THP
sysfs interface for anonymous shmem. But currently "THPeligible"
indicates only whether the mapping is eligible for allocating THP-pages as
well as the THP is PMD mappable or not for anonymous shmem, we need to
support semantics for mTHP with anonymous shmem similar to those for mTHP
with anonymous memory.
Link: https://lkml.kernel.org/r/20240705032309.24933-1-libang.li@antgroup.com Signed-off-by: Bang Li <libang.li@antgroup.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Lance Yang <ioworker0@gmail.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Ran Xiaokai [Fri, 5 Jul 2024 10:43:43 +0000 (10:43 +0000)]
kpageflags: detect isolated KPF_THP folios
When folio is isolated, the PG_lru bit is cleared. So the PG_lru check in
stable_page_flags() will miss this kind of isolated folios. Use
folio_test_large_rmappable() instead to also include isolated folios.
Since pagecache supports large folios and the introduction of mTHP, the
semantics of KPF_THP have been expanded, now it indicates not only
PMD-sized THP. Update related documentation to clearly state that KPF_THP
indicates multiple order THPs.
[ran.xiaokai@zte.com.cn: directly use is_zero_folio(), per David] Link: https://lkml.kernel.org/r/20240708062601.165215-1-ranxiaokai627@163.com Link: https://lkml.kernel.org/r/20240705104343.112680-1-ranxiaokai627@163.com Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn> Acked-by: David Hildenbrand <david@redhat.com> Cc: Andrei Vagin <avagin@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Muhammad Usama Anjum <usama.anjum@collabora.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Svetly Todorov <svetly.todorov@memverge.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Ryan Roberts [Thu, 4 Jul 2024 09:10:50 +0000 (10:10 +0100)]
mm: fix khugepaged activation policy
Since the introduction of mTHP, the docuementation has stated that
khugepaged would be enabled when any mTHP size is enabled, and disabled
when all mTHP sizes are disabled. There are 2 problems with this; 1.
this is not what was implemented by the code and 2. this is not the
desirable behavior.
Desirable behavior is for khugepaged to be enabled when any PMD-sized THP
is enabled, anon or file. (Note that file THP is still controlled by the
top-level control so we must always consider that, as well as the PMD-size
mTHP control for anon). khugepaged only supports collapsing to PMD-sized
THP so there is no value in enabling it when PMD-sized THP is disabled.
So let's change the code and documentation to reflect this policy.
Further, per-size enabled control modification events were not previously
forwarded to khugepaged to give it an opportunity to start or stop.
Consequently the following was resulting in khugepaged eroneously not
being activated:
echo never > /sys/kernel/mm/transparent_hugepage/enabled
echo always > /sys/kernel/mm/transparent_hugepage/hugepages-2048kB/enabled
memory tier: consolidate the initialization of memory tiers
The current memory tier initialization process is distributed across two
different functions, memory_tier_init() and memory_tier_late_init(). This
design is hard to maintain. Thus, this patch is proposed to reduce the
possible code paths by consolidating different initialization patches into
one.
The earlier discussion with Jonathan and Ying is listed here:
https://lore.kernel.org/lkml/20240405150244.00004b49@Huawei.com/
If we want to put these two initializations together, they must be placed
together in the later function. Because only at that time, the HMAT
information will be ready, adist between nodes can be calculated, and
memory tiering can be established based on the adist. So we position the
initialization at memory_tier_init() to the memory_tier_late_init() call.
Moreover, it's natural to keep memory_tier initialization in drivers at
device_initcall() level.
If we simply move the set_node_memory_tier() from memory_tier_init() to
late_initcall(), it will result in HMAT not registering the
mt_adistance_algorithm callback function, because set_node_memory_tier()
is not performed during the memory tiering initialization phase, leading
to a lack of correct default_dram information.
Therefore, we introduced a nodemask to pass the information of the default
DRAM nodes. The reason for not choosing to reuse default_dram_type->nodes
is that it is not clean enough. So in the end, we use a __initdata
variable, which is a variable that is released once initialization is
complete, including both CPU and memory nodes for HMAT to iterate through.
Link: https://lkml.kernel.org/r/20240704072646.437579-1-horen.chuang@linux.dev Signed-off-by: Ho-Ren (Jack) Chuang <horenchuang@bytedance.com> Suggested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Gregory Price <gourry.memverge@gmail.com> Cc: Len Brown <lenb@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Rafael J. Wysocki <rafael@kernel.org> Cc: Ravi Jonnalagadda <ravis.opensrc@micron.com> Cc: SeongJae Park <sj@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/page_counter: move calculating protection values to page_counter
It's a lot of math, and there is nothing memcontrol specific about it.
This makes it easier to use inside of the drm cgroup controller.
[akpm@linux-foundation.org: fix kerneldoc, per Jeff Johnson] Link: https://lkml.kernel.org/r/20240703112510.36424-1-maarten.lankhorst@linux.intel.com Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Jeff Johnson <quic_jjohnson@quicinc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: add comments for allocation helpers explaining why they are macros
A number of allocation helper functions were converted into macros to
account them at the call sites. Add a comment for each converted
allocation helper explaining why it has to be a macro and why we typecast
the return value wherever required. The patch also moves
acpi_os_acquire_object() closer to other allocation helpers to group them
together under the same comment. The patch has no functional changes.
Link: https://lkml.kernel.org/r/20240703174225.3891393-1-surenb@google.com Fixes: 2c321f3f70bc ("mm: change inlined allocation helpers to account at the call site") Signed-off-by: Suren Baghdasaryan <surenb@google.com> Suggested-by: Andrew Morton <akpm@linux-foundation.org> Cc: Christian König <christian.koenig@amd.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Jan Kara <jack@suse.cz> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Thorsten Blum <thorsten.blum@toblux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
powerpc/64s: use contiguous PMD/PUD instead of HUGEPD
On book3s/64, the only user of hugepd is hash in 4k mode.
All other setups (hash-64, radix-4, radix-64) use leaf PMD/PUD.
Rework hash-4k to use contiguous PMD and PUD instead.
In that setup there are only two huge page sizes: 16M and 16G.
16M sits at PMD level and 16G at PUD level.
pte_update doesn't know page size, lets use the same trick as
hpte_need_flush() to get page size from segment properties. That's not
the most efficient way but let's do that until callers of pte_update()
provide page size instead of just a huge flag.
Link: https://lkml.kernel.org/r/7448f60a9b3efd396595f4f735d1e0babc5ae379.1719928057.git.christophe.leroy@csgroup.eu Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
powerpc/e500: use contiguous PMD instead of hugepd
e500 supports many page sizes among which the following size are
implemented in the kernel at the time being: 4M, 16M, 64M, 256M, 1G.
On e500, TLB miss for hugepages is exclusively handled by SW even on e6500
which has HW assistance for 4k pages, so there are no constraints like on
the 8xx.
On e500/32, all are at PGD/PMD level and can be handled as cont-PMD.
On e500/64, smaller ones are on PMD while bigger ones are on PUD. Again,
they can easily be handled as cont-PMD and cont-PUD instead of hugepd.
On e500/32, use the pagesize bits in PTE to know if it is a PMD or a leaf
entry. This works because the pagesize bits are in the last 12 bits and
page tables are 4k aligned.
On e500/64, use highest bit which is always 1 on PxD (Because PxD contains
virtual address of a kernel memory) and always 0 on PTEs because not all
bits of RPN are used/possible.
Move r13 load after the call to FIND_PTE, and use r13 instead of r10 for
storing fault address. This will allow using r10 freely in FIND_PTE in
following patch to handle hugepage size.
Use PTE page size bits to encode hugepage size with the following format
corresponding to the values expected in bits 52-55 in MAS1 register.
Those bits are called TSIZE:
0001 4 Kbyte
0010 16 Kbyte
0011 64 Kbyte
0100 256 Kbyte
0101 1 Mbyte
0110 4 Mbyte
0111 16 Mbyte
1000 64 Mbyte
1001 256 Mbyte
1010 1 Gbyte
1011 4 Gbyte
1100 16 Gbyte
1101 64 Gbyte
1110 256 Gbyte
1111 1 Tbyte
It corresponds to shift value minus 10 with lowest bit removed.
It is not the value expected in the PTE in that field, but only e6500
performs HW based TLB loading and the e6500 reference manual explicitely
says that this field is ignored.
Also add pte_huge_size() which will be used later.
powerpc/e500: remove enc and ind fields from struct mmu_psize_def
enc field is hidden behind BOOK3E_PAGESZ_XX macros, and when you look
closer you realise that this field is nothing else than the value of shift
minus ten.
So remove enc field and calculate tsize from shift field.
powerpc/8xx: rework support for 8M pages using contiguous PTE entries
In order to fit better with standard Linux page tables layout, add support
for 8M pages using contiguous PTE entries in a standard page table. Page
tables will then be populated with 1024 similar entries and two PMD
entries will point to that page table.
The PMD entries also get a flag to tell it is addressing an 8M page, this
is required for the HW tablewalk assistance.
powerpc/mm: fix __find_linux_pte() on 32 bits with PMD leaf entries
Building on 32 bits with pmd_leaf() not returning always false leads to
the following error:
CC arch/powerpc/mm/pgtable.o
arch/powerpc/mm/pgtable.c: In function '__find_linux_pte':
arch/powerpc/mm/pgtable.c:506:1: error: function may return address of local variable [-Werror=return-local-addr]
506 | }
| ^
arch/powerpc/mm/pgtable.c:394:15: note: declared here
394 | pud_t pud, *pudp;
| ^~~
arch/powerpc/mm/pgtable.c:394:15: note: declared here
This is due to pmd_offset() being a no-op in that case.
So rework it for powerpc/32 so that pXd_offset() are used on real
pointers and not on on-stack copies.
Behind fixing the problem, it also has the advantage of simplifying
__find_linux_pte() including the removal of stack frame:
mm: provide mm_struct and address to huge_ptep_get()
On powerpc 8xx huge_ptep_get() will need to know whether the given ptep is
a PTE entry or a PMD entry. This cannot be known with the PMD entry
itself because there is no easy way to know it from the content of the
entry.
So huge_ptep_get() will need to know either the size of the page or get
the pmd.
In order to be consistent with huge_ptep_get_and_clear(), give mm and
address to huge_ptep_get().
mm: define __pte_leaf_size() to also take a PMD entry
On powerpc 8xx, when a page is 8M size, the information is in the PMD
entry. So allow architectures to provide __pte_leaf_size() instead of
pte_leaf_size() and provide the PMD entry to that function.
When __pte_leaf_size() is not defined, define it as a pte_leaf_size() so
that architectures not interested in the PMD arguments are not impacted.
Only define a default pte_leaf_size() when __pte_leaf_size() is not
defined to make sure nobody adds new calls to pte_leaf_size() in the core.
Michael Ellerman [Tue, 2 Jul 2024 13:51:18 +0000 (15:51 +0200)]
powerpc/64e: drop unused TLB miss handlers
There are two possibilities for book3e_htw_mode, PPC_HTW_E6500 or
PPC_HTW_NONE.
The TLB miss handlers are patched to use, respectively:
- exc_[data|indstruction]_tlb_miss_e6500_book3e
- exc_[data|indstruction]_tlb_miss_bolted_book3e
Which means the default handlers are never used. Remove those, and use
the bolted handlers (PPC_HTW_NONE) by default.
Link: https://lkml.kernel.org/r/9a670adc1771fb1871fba93ace5372f7eadc286f.1719928057.git.christophe.leroy@csgroup.eu Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Michael Ellerman [Tue, 2 Jul 2024 13:51:17 +0000 (15:51 +0200)]
powerpc/64e: consolidate TLB miss handler patching
The 64e TLB miss handler patching is done in setup_mmu_htw(), and then
again immediately afterward in early_init_mmu_global(). Consolidate it
into a single location.
Link: https://lkml.kernel.org/r/7033b37493fb48a3e5245b59d0a42afb75dabfc1.1719928057.git.christophe.leroy@csgroup.eu Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Michael Ellerman [Tue, 2 Jul 2024 13:51:16 +0000 (15:51 +0200)]
powerpc/64e: drop MMU_FTR_TYPE_FSL_E checks in 64-bit code
All 64-bit Book3E have MMU_FTR_TYPE_FSL_E, since A2 was removed, so remove
checks for it in 64-bit only code.
Link: https://lkml.kernel.org/r/2b0b0bc9752e6cece222e4e2050358da70bb631d.1719928057.git.christophe.leroy@csgroup.eu Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Michael Ellerman [Tue, 2 Jul 2024 13:51:15 +0000 (15:51 +0200)]
powerpc/64e: drop E500 ifdefs in 64-bit code
All 64-bit Book3E have E500=y, so drop the unneeded ifdefs.
Link: https://lkml.kernel.org/r/7fb88809c88a1b774063eda602a9333079403f83.1719928057.git.christophe.leroy@csgroup.eu Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Michael Ellerman [Tue, 2 Jul 2024 13:51:14 +0000 (15:51 +0200)]
powerpc/64e: split out nohash Book3E 64-bit code
A reasonable chunk of nohash/tlb.c is 64-bit only code, split it out into
a separate file.
Link: https://lkml.kernel.org/r/cb2b118f9d8a86f82d01bfb9ad309d1d304480a1.1719928057.git.christophe.leroy@csgroup.eu Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Michael Ellerman [Tue, 2 Jul 2024 13:51:13 +0000 (15:51 +0200)]
powerpc/64e: remove unused IBM HTW code
Patch series "Reimplement huge pages without hugepd on powerpc (8xx, e500,
book3s/64)", v7.
Unlike most architectures, powerpc 8xx HW requires a two-level pagetable
topology for all page sizes. So a leaf PMD-contig approach is not
feasible as such.
Possible sizes on 8xx are 4k, 16k, 512k and 8M.
First level (PGD/PMD) covers 4M per entry. For 8M pages, two PMD entries
must point to a single entry level-2 page table. Until now that was done
using hugepd. This series changes it to use standard page tables where
the entry is replicated 1024 times on each of the two pagetables refered
by the two associated PMD entries for that 8M page.
For e500 and book3s/64 there are less constraints because it is not tied
to the HW assisted tablewalk like on 8xx, so it is easier to use leaf PMDs
(and PUDs).
On e500 the supported page sizes are 4M, 16M, 64M, 256M and 1G. All at
PMD level on e500/32 (mpc85xx) and mix of PMD and PUD for e500/64. We
encode page size with 4 available bits in PTE entries. On e300/32 PGD
entries size is increases to 64 bits in order to allow leaf-PMD entries
because PTE are 64 bits on e500.
On book3s/64 only the hash-4k mode is concerned. It supports 16M pages as
cont-PMD and 16G pages as cont-PUD. In other modes (radix-4k, radix-6k
and hash-64k) the sizes match with PMD and PUD sizes so that's just leaf
entries. The hash processing make things a bit more complex. To ease
things, __hash_page_huge() is modified to bail out when DIRTY or ACCESSED
bits are missing, leaving it to mm core to fix it.
This patch (of 23):
The nohash HTW_IBM (Hardware Table Walk) code is unused since support for
A2 was removed in commit fb5a515704d7 ("powerpc: Remove platforms/ wsp and
associated pieces") (2014).
The remaining supported CPUs use either no HTW (data_tlb_miss_bolted), or
the e6500 HTW (data_tlb_miss_e6500).
o Rename class_stat_inc() and class_stat_dec() to class_stat_add()
and class_stat_sub() correspondingly. inc/dec are usually associated
with +1/-1 modifications, while zsmlloc can modify stats by up
to ->objs_per_zspage. Use add/sub (follow atomics naming).
o Rename zs_stat_get() to class_stat_read()
get() is usually associated with ref-counting and is paired with put().
zs_stat_get() simply reads class stat so rename to reflect it.
(This also follows atomics naming).
Lance Yang [Fri, 28 Jun 2024 13:07:49 +0000 (21:07 +0800)]
mm: add per-order mTHP split counters
Patch series "mm: introduce per-order mTHP split counters", v3.
At present, the split counters in THP statistics no longer include
PTE-mapped mTHP. Therefore, we want to introduce per-order mTHP split
counters to monitor the frequency of mTHP splits. This will assist
developers in better analyzing and optimizing system performance.
Currently, the split counters in THP statistics no longer include
PTE-mapped mTHP. Therefore, we propose introducing per-order mTHP split
counters to monitor the frequency of mTHP splits. This will help
developers better analyze and optimize system performance.
Chengming Zhou [Thu, 27 Jun 2024 07:59:59 +0000 (15:59 +0800)]
mm/zsmalloc: move record_obj() into obj_malloc()
We always record_obj() to make handle points to object after obj_malloc(),
so simplify the code by moving record_obj() into obj_malloc(). There
should be no functional change.
Andrii Nakryiko [Thu, 27 Jun 2024 17:08:58 +0000 (10:08 -0700)]
selftests/proc: add PROCMAP_QUERY ioctl tests
Extend existing proc-pid-vm.c tests with PROCMAP_QUERY ioctl() API. Test
a few successful and negative cases, validating querying filtering and
exact vs next VMA logic works as expected.
Link: https://lkml.kernel.org/r/20240627170900.1672542-7-andrii@kernel.org Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andrii Nakryiko [Thu, 27 Jun 2024 17:08:56 +0000 (10:08 -0700)]
docs/procfs: call out ioctl()-based PROCMAP_QUERY command existence
Call out PROCMAP_QUERY ioctl() existence in the section describing
/proc/PID/maps file in documentation. We refer user to UAPI header for
low-level details of this programmatic interface.
Link: https://lkml.kernel.org/r/20240627170900.1672542-5-andrii@kernel.org Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andrii Nakryiko [Thu, 27 Jun 2024 17:08:55 +0000 (10:08 -0700)]
fs/procfs: add build ID fetching to PROCMAP_QUERY API
The need to get ELF build ID reliably is an important aspect when dealing
with profiling and stack trace symbolization, and /proc/<pid>/maps textual
representation doesn't help with this.
To get backing file's ELF build ID, application has to first resolve VMA,
then use it's start/end address range to follow a special
/proc/<pid>/map_files/<start>-<end> symlink to open the ELF file (this is
necessary because backing file might have been removed from the disk or
was already replaced with another binary in the same file path.
Such approach, beyond just adding complexity of having to do a bunch of
extra work, has extra security implications. Because application opens
underlying ELF file and needs read access to its entire contents (as far
as kernel is concerned), kernel puts additional capable() checks on
following /proc/<pid>/map_files/<start>-<end> symlink. And that makes
sense in general.
But in the case of build ID, profiler/symbolizer doesn't need the contents
of ELF file, per se. It's only build ID that is of interest, and ELF
build ID itself doesn't provide any sensitive information.
So this patch adds a way to request backing file's ELF build ID along the
rest of VMA information in the same API. User has control over whether
this piece of information is requested or not by either setting
build_id_size field to zero or non-zero maximum buffer size they provided
through build_id_addr field (which encodes user pointer as __u64 field).
This is a completely optional piece of information, and so has no
performance implications for user cases that don't care about build ID,
while improving performance and simplifying the setup for those
application that do need it.
Kernel already implements build ID fetching, which is used from BPF
subsystem. We are reusing this code here, but plan a follow up changes to
make it work better under more relaxed assumption (compared to what
existing code assumes) of being called from user process context, in which
page faults are allowed. BPF-specific implementation currently bails out
if necessary part of ELF file is not paged in, all due to extra
BPF-specific restrictions (like the need to fetch build ID in restrictive
contexts such as NMI handler).
[andrii@kernel.org: fix integer to pointer cast warning in do_procmap_query()] Link: https://lkml.kernel.org/r/20240701174805.1897344-1-andrii@kernel.org Link: https://lkml.kernel.org/r/20240627170900.1672542-4-andrii@kernel.org Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andrii Nakryiko [Thu, 27 Jun 2024 17:08:54 +0000 (10:08 -0700)]
fs/procfs: implement efficient VMA querying API for /proc/<pid>/maps
/proc/<pid>/maps file is extremely useful in practice for various tasks
involving figuring out process memory layout, what files are backing any
given memory range, etc. One important class of applications that
absolutely rely on this are profilers/stack symbolizers (perf tool being
one of them). Patterns of use differ, but they generally would fall into
two categories.
In on-demand pattern, a profiler/symbolizer would normally capture stack
trace containing absolute memory addresses of some functions, and would
then use /proc/<pid>/maps file to find corresponding backing ELF files
(normally, only executable VMAs are of interest), file offsets within
them, and then continue from there to get yet more information (ELF
symbols, DWARF information) to get human-readable symbolic information.
This pattern is used by Meta's fleet-wide profiler, as one example.
In preprocessing pattern, application doesn't know the set of addresses of
interest, so it has to fetch all relevant VMAs (again, probably only
executable ones), store or cache them, then proceed with profiling and
stack trace capture. Once done, it would do symbolization based on stored
VMA information. This can happen at much later point in time. This
patterns is used by perf tool, as an example.
In either case, there are both performance and correctness requirement
involved. This address to VMA information translation has to be done as
efficiently as possible, but also not miss any VMA (especially in the case
of loading/unloading shared libraries). In practice, correctness can't be
guaranteed (due to process dying before VMA data can be captured, or
shared library being unloaded, etc), but any effort to maximize the chance
of finding the VMA is appreciated.
Unfortunately, for all the /proc/<pid>/maps file universality and
usefulness, it doesn't fit the above use cases 100%.
First, it's main purpose is to emit all VMAs sequentially, but in practice
captured addresses would fall only into a smaller subset of all process'
VMAs, mainly containing executable text. Yet, library would need to parse
most or all of the contents to find needed VMAs, as there is no way to
skip VMAs that are of no use. Efficient library can do the linear pass
and it is still relatively efficient, but it's definitely an overhead that
can be avoided, if there was a way to do more targeted querying of the
relevant VMA information.
Second, it's a text based interface, which makes its programmatic use from
applications and libraries more cumbersome and inefficient due to the need
to handle text parsing to get necessary pieces of information. The
overhead is actually payed both by kernel, formatting originally binary
VMA data into text, and then by user space application, parsing it back
into binary data for further use.
For the on-demand pattern of usage, described above, another problem when
writing generic stack trace symbolization library is an unfortunate
performance-vs-correctness tradeoff that needs to be made. Library has to
make a decision to either cache parsed contents of /proc/<pid>/maps (after
initial processing) to service future requests (if application requests to
symbolize another set of addresses (for the same process), captured at
some later time, which is typical for periodic/continuous profiling cases)
to avoid higher costs of re-parsing this file. Or it has to choose to
cache the contents in memory to speed up future requests. In the former
case, more memory is used for the cache and there is a risk of getting
stale data if application loads or unloads shared libraries, or otherwise
changed its set of VMAs somehow, e.g., through additional mmap() calls.
In the latter case, it's the performance hit that comes from re-opening
the file and re-parsing its contents all over again.
This patch aims to solve this problem by providing a new API built on top
of /proc/<pid>/maps. It's meant to address both non-selectiveness and
text nature of /proc/<pid>/maps, by giving user more control of what sort
of VMA(s) needs to be queried, and being binary-based interface eliminates
the overhead of text formatting (on kernel side) and parsing (on user
space side).
It's also designed to be extensible and forward/backward compatible by
including required struct size field, which user has to provide. We use
established copy_struct_from_user() approach to handle extensibility.
User has a choice to pick either getting VMA that covers provided address
or -ENOENT if none is found (exact, least surprising, case). Or, with an
extra query flag (PROCMAP_QUERY_COVERING_OR_NEXT_VMA), they can get either
VMA that covers the address (if there is one), or the closest next VMA
(i.e., VMA with the smallest vm_start > addr). The latter allows more
efficient use, but, given it could be a surprising behavior, requires an
explicit opt-in.
There is another query flag that is useful for some use cases.
PROCMAP_QUERY_FILE_BACKED_VMA instructs this API to only return
file-backed VMAs. Combining this with PROCMAP_QUERY_COVERING_OR_NEXT_VMA
makes it possible to efficiently iterate only file-backed VMAs of the
process, which is what profilers/symbolizers are normally interested in.
All the above querying flags can be combined with (also optional) set of
desired VMA permissions flags. This allows to, for example, iterate only
an executable subset of VMAs, which is what preprocessing pattern, used by
perf tool, would benefit from, as the assumption is that captured stack
traces would have addresses of executable code. This saves time by
skipping non-executable VMAs altogether efficienty.
All these querying flags (modifiers) are orthogonal and can be combined in
a semantically meaningful and natural way.
Basing this ioctl()-based API on top of /proc/<pid>/maps's FD makes sense
given it's querying the same set of VMA data. It's also benefitial
because permission checks for /proc/<pid>/maps is performed at open time
once, and the actual data read of text contents of /proc/<pid>/maps is
done without further permission checks. We piggyback on this pattern with
ioctl()-based API as well, as that's a desired property. Both for
performance reasons, but also for security and flexibility reasons.
Allowing application to open an FD for /proc/self/maps without any extra
capabilities, and then passing it to some sort of profiling agent through
Unix-domain socket, would allow such profiling agent to not require some
of the capabilities that are otherwise expected when opening
/proc/<pid>/maps file for *another* process. This is a desirable property
for some more restricted setups.
This new ioctl-based implementation doesn't interfere with seq_file-based
implementation of /proc/<pid>/maps textual interface, and so could be used
together or independently without paying any price for that.
Note also, that fetching VMA name (e.g., backing file path, or special
hard-coded or user-provided names) is optional just like build ID. If
user sets vma_name_size to zero, kernel code won't attempt to retrieve it,
saving resources.
Earlier versions of this patch set were adding per-VMA locking, which is
why we have a code structure that is ready for abstracting mmap_lock vs
vm_lock differences (query_vma_setup(), query_vma_teardown(), and
query_vma_find_by_addr()), but given anon_vma_name() is not yet compatible
with per-VMA locking, initial implementation sticks to using only
mmap_lock for now. It will be easy to add back per-VMA locking once all
the pieces are ready later on. Which is why we keep existing code
structure with setup/teardown/query helper functions.
[andrii@kernel.org: improve PROCMAP_QUERY's compat mode handling] Link: https://lkml.kernel.org/r/20240701174805.1897344-2-andrii@kernel.org Link: https://lkml.kernel.org/r/20240627170900.1672542-3-andrii@kernel.org Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andrii Nakryiko [Thu, 27 Jun 2024 17:08:53 +0000 (10:08 -0700)]
fs/procfs: extract logic for getting VMA name constituents
Patch series "ioctl()-based API to query VMAs from /proc/<pid>/maps", v6.
Implement binary ioctl()-based interface to /proc/<pid>/maps file to allow
applications to query VMA information more efficiently than reading *all*
VMAs nonselectively through text-based interface of /proc/<pid>/maps file.
Patch #2 goes into a lot of details and background on some common patterns
of using /proc/<pid>/maps in the area of performance profiling and
subsequent symbolization of captured stack traces. As mentioned in that
patch, patterns of VMA querying can differ depending on specific use case,
but can generally be grouped into two main categories: the need to query a
small subset of VMAs covering a given batch of addresses, or
reading/storing/caching all (typically, executable) VMAs upfront for later
processing.
The new PROCMAP_QUERY ioctl() API added in this patch set was motivated by
the former pattern of usage. Earlier revisions had a patch adding a tool
that faithfully reproduces an efficient VMA matching pass of a symbolizer,
collecting a subset of covering VMAs for a given set of addresses as
efficiently as possible. This tool served both as a testing ground, as
well as a benchmarking tool. It implements everything both for currently
existing text-based /proc/<pid>/maps interface, as well as for newly-added
PROCMAP_QUERY ioctl(). This revision dropped the tool from the patch set
and, once the API lands upstream, this tool might be added separately on
Github as an example.
Based on discussion on earlier revisions of this patch set, it turned out
that this ioctl() API is competitive with highly-optimized text-based
pre-processing pattern that perf tool is using. Based on perf discussion,
this revision adds more flexibility in specifying a subset of VMAs that
are of interest. Now it's possible to specify desired permissions of VMAs
(e.g., request only executable ones) and/or restrict to only a subset of
VMAs that have file backing. This further improves the efficiency when
using this new API thanks to more selective (executable VMAs only)
querying.
In addition to a custom benchmarking tool, and experimental perf
integration (available at [0]), Daniel Mueller has since also implemented
an experimental integration into blazesym (see [1]), a library used for
stack trace symbolization by our server fleet-wide profiler and another
on-device profiler agent that runs on weaker ARM devices. The latter
ARM-based device profiler is especially sensitive to performance, and so
we benchmarked and compared text-based /proc/<pid>/maps solution to the
equivalent one using PROCMAP_QUERY ioctl().
Results are very encouraging, giving us 5x improvement for end-to-end
so-called "address normalization" pass, which is the part of the
symbolization process that happens locally on ARM device, before being
sent out for further heavier-weight processing on more powerful remote
server. Note that this is not an artificial microbenchmark. It's a full
end-to-end API call being measured with real-world data on real-world
device.
You can see above that we see the drop from 50µs down to 10µs for
exactly the same amount of work, with the same data and target process.
With the aforementioned custom tool, we see about ~40x improvement (it
might vary a bit, depending on a specific captured set of addresses). And
even for perf-based benchmark it's on par or slightly ahead when using
permission-based filtering (fetching only executable VMAs).
Earlier revisions attempted to use per-VMA locking, if kernel was compiled
with CONFIG_PER_VMA_LOCK=y, but it turned out that anon_vma_name() is not
yet compatible with per-VMA locking and assumes mmap_lock to be taken,
which makes the use of per-VMA locking for this API premature. It was
agreed ([2]) to continue for now with just mmap_lock, but the code
structure is such that it should be easy to add per-VMA locking support
once all the pieces are ready.
One thing that did not change was basing this new API as an ioctl()
command on /proc/<pid>/maps file. An ioctl-based API on top of pidfd was
considered, but has its own downsides. Implementing ioctl() directly on
pidfd will cause access permission checks on every single ioctl(), which
leads to performance concerns and potential spam of capable() audit
messages. It also prevents a nice pattern, possible with
/proc/<pid>/maps, in which application opens /proc/self/maps FD (requiring
no additional capabilities) and passed this FD to profiling agent for
querying. To achieve similar pattern, a new file would have to be created
from pidf just for VMA querying, which is considered to be inferior to
just querying /proc/<pid>/maps FD as proposed in current approach. These
aspects were discussed in the hallway track at recent LSF/MM/BPF 2024 and
sticking to procfs ioctl() was the final agreement we arrived at.
Extract generic logic to fetch relevant pieces of data to describe VMA
name. This could be just some string (either special constant or
user-provided), or a string with some formatted wrapping text (e.g.,
"[anon_shmem:<something>]"), or, commonly, file path. seq_file-based
logic has different methods to handle all three cases, but they are
currently mixed in with extracting underlying sources of data.
This patch splits this into data fetching and data formatting, so that
data fetching can be reused later on.
There should be no functional changes.
Link: https://lkml.kernel.org/r/20240627170900.1672542-1-andrii@kernel.org Link: https://lkml.kernel.org/r/20240627170900.1672542-2-andrii@kernel.org Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Vivek Kasireddy [Mon, 24 Jun 2024 06:36:17 +0000 (23:36 -0700)]
selftests/udmabuf: add tests to verify data after page migration
Since the memfd pages associated with a udmabuf may be migrated as part of
udmabuf create, we need to verify the data coherency after successful
migration. The new tests added in this patch try to do just that using 4k
sized pages and also 2 MB sized huge pages for the memfd.
Successful completion of the tests would mean that there is no disconnect
between the memfd pages and the ones associated with a udmabuf. And,
these tests can also be augmented in the future to test newer udmabuf
features (such as handling memfd hole punch).
The idea for these tests comes from a patch by Mike Kravetz here:
https://lists.freedesktop.org/archives/dri-devel/2023-June/410623.html
v1->v2: (suggestions from Shuah)
- Use ksft_* functions to print and capture results of tests
- Use appropriate KSFT_* status codes for exit()
- Add Mike Kravetz's suggested-by tag
Link: https://lkml.kernel.org/r/20240624063952.1572359-10-vivek.kasireddy@intel.com Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Dave Airlie <airlied@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Cc: Shuah Khan <shuah@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Hugh Dickins <hughd@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Dongwon Kim <dongwon.kim@intel.com> Cc: Junxiao Chang <junxiao.chang@intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@infradead.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Vivek Kasireddy [Mon, 24 Jun 2024 06:36:16 +0000 (23:36 -0700)]
udmabuf: pin the pages using memfd_pin_folios() API
Using memfd_pin_folios() will ensure that the pages are pinned
correctly using FOLL_PIN. And, this also ensures that we don't
accidentally break features such as memory hotunplug as it would
not allow pinning pages in the movable zone.
Using this new API also simplifies the code as we no longer have
to deal with extracting individual pages from their mappings or
handle shmem and hugetlb cases separately.
Link: https://lkml.kernel.org/r/20240624063952.1572359-9-vivek.kasireddy@intel.com Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com> Acked-by: Dave Airlie <airlied@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Hugh Dickins <hughd@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Dongwon Kim <dongwon.kim@intel.com> Cc: Junxiao Chang <junxiao.chang@intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@infradead.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Vivek Kasireddy [Mon, 24 Jun 2024 06:36:15 +0000 (23:36 -0700)]
udmabuf: convert udmabuf driver to use folios
This is mainly a preparatory patch to use memfd_pin_folios() API for
pinning folios. Using folios instead of pages makes sense as the udmabuf
driver needs to handle both shmem and hugetlb cases. And, using the
memfd_pin_folios() API makes this easier as we no longer need to
separately handle shmem vs hugetlb cases in the udmabuf driver.
Note that, the function vmap_udmabuf() still needs a list of pages; so, we
collect all the head pages into a local array in this case.
Other changes in this patch include the addition of helpers for checking
the memfd seals and exporting dmabuf. Moving code from udmabuf_create()
into these helpers improves readability given that udmabuf_create() is a
bit long.
Link: https://lkml.kernel.org/r/20240624063952.1572359-8-vivek.kasireddy@intel.com Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com> Acked-by: Dave Airlie <airlied@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Hugh Dickins <hughd@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Dongwon Kim <dongwon.kim@intel.com> Cc: Junxiao Chang <junxiao.chang@intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@infradead.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Vivek Kasireddy [Mon, 24 Jun 2024 06:36:14 +0000 (23:36 -0700)]
udmabuf: add back support for mapping hugetlb pages
A user or admin can configure a VMM (Qemu) Guest's memory to be backed by
hugetlb pages for various reasons. However, a Guest OS would still
allocate (and pin) buffers that are backed by regular 4k sized pages. In
order to map these buffers and create dma-bufs for them on the Host, we
first need to find the hugetlb pages where the buffer allocations are
located and then determine the offsets of individual chunks (within those
pages) and use this information to eventually populate a scatterlist.
Testcase: default_hugepagesz=2M hugepagesz=2M hugepages=2500 options
were passed to the Host kernel and Qemu was launched with these
relevant options: qemu-system-x86_64 -m 4096m....
-device virtio-gpu-pci,max_outputs=1,blob=true,xres=1920,yres=1080
-display gtk,gl=on
-object memory-backend-memfd,hugetlb=on,id=mem1,size=4096M
-machine memory-backend=mem1
Replacing -display gtk,gl=on with -display gtk,gl=off above would
exercise the mmap handler.
Link: https://lkml.kernel.org/r/20240624063952.1572359-7-vivek.kasireddy@intel.com Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> (v2) Acked-by: Dave Airlie <airlied@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Cc: David Hildenbrand <david@redhat.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Hugh Dickins <hughd@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Dongwon Kim <dongwon.kim@intel.com> Cc: Junxiao Chang <junxiao.chang@intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@infradead.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Vivek Kasireddy [Mon, 24 Jun 2024 06:36:11 +0000 (23:36 -0700)]
mm/gup: introduce memfd_pin_folios() for pinning memfd folios
For drivers that would like to longterm-pin the folios associated with a
memfd, the memfd_pin_folios() API provides an option to not only pin the
folios via FOLL_PIN but also to check and migrate them if they reside in
movable zone or CMA block. This API currently works with memfds but it
should work with any files that belong to either shmemfs or hugetlbfs.
Files belonging to other filesystems are rejected for now.
The folios need to be located first before pinning them via FOLL_PIN. If
they are found in the page cache, they can be immediately pinned.
Otherwise, they need to be allocated using the filesystem specific APIs
and then pinned.
[akpm@linux-foundation.org: improve the CONFIG_MMU=n situation, per SeongJae]
[vivek.kasireddy@intel.com: return -EINVAL if the end offset is greater than the size of memfd] Link: https://lkml.kernel.org/r/IA0PR11MB71850525CBC7D541CAB45DF1F8DB2@IA0PR11MB7185.namprd11.prod.outlook.com Link: https://lkml.kernel.org/r/20240624063952.1572359-4-vivek.kasireddy@intel.com Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com> Suggested-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> (v2) Reviewed-by: David Hildenbrand <david@redhat.com> (v3) Reviewed-by: Christoph Hellwig <hch@lst.de> (v6) Acked-by: Dave Airlie <airlied@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Hugh Dickins <hughd@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Dongwon Kim <dongwon.kim@intel.com> Cc: Junxiao Chang <junxiao.chang@intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@infradead.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This helper is the folio equivalent of check_and_migrate_movable_pages().
Therefore, all the rules that apply to check_and_migrate_movable_pages()
also apply to this one as well. Currently, this helper is only used by
memfd_pin_folios().
This patch also includes changes to rename and convert the internal
functions collect_longterm_unpinnable_pages() and
migrate_longterm_unpinnable_pages() to work on folios. As a result,
check_and_migrate_movable_pages() is now a wrapper around
check_and_migrate_movable_folios().
Link: https://lkml.kernel.org/r/20240624063952.1572359-3-vivek.kasireddy@intel.com Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com> Suggested-by: David Hildenbrand <david@redhat.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Dave Airlie <airlied@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Peter Xu <peterx@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Dongwon Kim <dongwon.kim@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Junxiao Chang <junxiao.chang@intel.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/gup: Introduce memfd_pin_folios() for pinning memfd
folios", v16.
Currently, some drivers (e.g, Udmabuf) that want to longterm-pin the
pages/folios associated with a memfd, do so by simply taking a reference
on them. This is not desirable because the pages/folios may reside in
Movable zone or CMA block.
Therefore, having drivers use memfd_pin_folios() API ensures that the
folios are appropriately pinned via FOLL_PIN for longterm DMA.
This patchset also introduces a few helpers and converts the Udmabuf
driver to use folios and memfd_pin_folios() API to longterm-pin the folios
for DMA. Two new Udmabuf selftests are also included to test the driver
and the new API.
This patch (of 9):
These helpers are the folio versions of unpin_user_page/unpin_user_pages.
They are currently only useful for unpinning folios pinned by
memfd_pin_folios() or other associated routines. However, they could find
new uses in the future, when more and more folio-only helpers are added to
GUP.
We should probably sanity check the folio as part of unpin similar to how
it is done in unpin_user_page/unpin_user_pages but we cannot cleanly do
that at the moment without also checking the subpage. Therefore, sanity
checking needs to be added to these routines once we have a way to
determine if any given folio is anon-exclusive (via a per folio
AnonExclusive flag).
Link: https://lkml.kernel.org/r/20240624063952.1572359-1-vivek.kasireddy@intel.com Link: https://lkml.kernel.org/r/20240624063952.1572359-2-vivek.kasireddy@intel.com Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com> Suggested-by: David Hildenbrand <david@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Dave Airlie <airlied@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Peter Xu <peterx@redhat.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Dongwon Kim <dongwon.kim@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Junxiao Chang <junxiao.chang@intel.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Chengming Zhou [Mon, 17 Jun 2024 12:57:41 +0000 (20:57 +0800)]
mm/zswap: use only one pool in zswap
Zswap uses 32 pools to workaround the locking scalability problem in zswap
backends (mainly zsmalloc nowadays), which brings its own problems like
memory waste and more memory fragmentation.
Testing results show that we can have near performance with only one pool
in zswap after changing zsmalloc to use per-size_class lock instead of
pool spinlock.
Testing kernel build (make bzImage -j32) on tmpfs with memory.max=1GB, and
zswap shrinker enabled with 10GB swapfile on ext4.
real user sys
6.10.0-rc3 138.18 1241.38 1452.73
6.10.0-rc3-onepool 149.45 1240.45 1844.69
6.10.0-rc3-onepool-perclass 138.23 1242.37 1469.71
And do the same testing using zbud, which shows a little worse performance
as expected since we don't do any locking optimization for zbud. I think
it's acceptable since zsmalloc became a lot more popular than other
backends, and we may want to support only zsmalloc in the future.
real user sys
6.10.0-rc3-zbud 138.23 1239.58 1430.09
6.10.0-rc3-onepool-zbud 139.64 1241.37 1516.59
Chengming Zhou [Mon, 17 Jun 2024 12:57:40 +0000 (20:57 +0800)]
mm/zsmalloc: change back to per-size_class lock
Patch series "mm/zsmalloc: change back to per-size_class lock, v2".
Commit c0547d0b6a4b ("zsmalloc: consolidate zs_pool's migrate_lock and
size_class's locks") changed per-size_class lock to pool spinlock to
prepare reclaim support in zsmalloc. Then reclaim support in zsmalloc had
been dropped in favor of LRU reclaim in zswap, but this locking change had
been left there.
Obviously, the scalability of pool spinlock is worse than per-size_class.
And we have a workaround that using 32 pools in zswap to avoid this
scalability problem, which brings its own problems like memory waste and
more memory fragmentation.
So this series changes back to use per-size_class lock and using testing
data in much stressed situation to verify that we can use only one pool in
zswap. Note we only test and care about the zsmalloc backend, which makes
sense now since zsmalloc became a lot more popular than other backends.
Testing kernel build (make bzImage -j32) on tmpfs with memory.max=1GB, and
zswap shrinker enabled with 10GB swapfile on ext4.
real user sys
6.10.0-rc3 138.18 1241.38 1452.73
6.10.0-rc3-onepool 149.45 1240.45 1844.69
6.10.0-rc3-onepool-perclass 138.23 1242.37 1469.71
We can see from "sys" column that per-size_class locking with only one
pool in zswap can have near performance with the current 32 pools.
This patch (of 2):
This patch is almost the revert of the commit c0547d0b6a4b ("zsmalloc:
consolidate zs_pool's migrate_lock and size_class's locks"), which changed
to use a global pool->lock instead of per-size_class lock and
pool->migrate_lock, was preparation for suppporting reclaim in zsmalloc.
Then reclaim in zsmalloc had been dropped in favor of LRU reclaim in
zswap.
In theory, per-size_class is more fine-grained than the pool->lock, since
a pool can have many size_classes. As for the additional
pool->migrate_lock, only free() and map() need to grab it to access stable
handle to get zspage, and only in read lock mode.
Barry Song [Sat, 29 Jun 2024 23:22:31 +0000 (11:22 +1200)]
mm: zswap: fix zswap_never_enabled() for CONFIG_ZSWAP==N
If CONFIG_ZSWAP is set to N, it means zswap cannot be enabled.
zswap_never_enabled() should return true.
The only effect of this issue is that with Barry's latest large folio
swapin patches for zram ("mm: support mTHP swap-in for zRAM-like
swapfile"), we will always fallback to order-0 swapin, even mistakenly
when !CONFIG_ZSWAP.
Basically this bug makes Barry's in progress patches not work at all.
The API was created to inform the mm core that zswap has never been
enabled, allowing the mm core to perform mTHP swap-in. This is a
transitional solution until zswap supports mTHP. If zswap has been
enabled, performing mTHP swap-in will result in corrupted data. You
may find the answer in the mTHP swap-in series:
Link: https://lkml.kernel.org/r/20240629232231.42394-1-21cnbao@gmail.com Fixes: 0300e17d67c3 ("mm: zswap: add zswap_never_enabled()") Signed-off-by: Barry Song <v-songbaohua@oppo.com> Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev> Acked-by: Yosry Ahmed <yosryahmed@google.com> Acked-by: Chris Li <chrisl@kernel.org> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Nhat Pham <nphamcs@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Barry Song [Sat, 29 Jun 2024 23:41:55 +0000 (11:41 +1200)]
mm/vmscan: drop checking if _deferred_list is empty before using TTU_SYNC
The optimization of list_empty(&folio->_deferred_list) aimed to prevent
increasing the PTL duration when a large folio is partially unmapped, for
example, from subpage 0 to subpage (nr - 2).
But Ryan's commit 5ed890ce5147 ("mm: vmscan: avoid split during
shrink_folio_list()") actually splits this kind of large folios. This
makes the "optimization" useless.
Additionally, the list_empty() technically required a data_race()
annotation.
Link: https://lkml.kernel.org/r/20240629234155.53524-1-21cnbao@gmail.com Signed-off-by: Barry Song <v-songbaohua@oppo.com> Reviewed-by: Ryan Roberts <ryan.roberts@arm.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Wei Yang [Tue, 2 Jul 2024 02:09:31 +0000 (02:09 +0000)]
mm/page_alloc: remove prefetchw() on freeing page to buddy system
The prefetchw() is introduced from an ancient patch[1].
The change log says:
The basic idea is to free higher order pages instead of going
through every single one. Also, some unnecessary atomic operations
are done away with and replaced with non-atomic equivalents, and
prefetching is done where it helps the most. For a more in-depth
discusion of this patch, please see the linux-ia64 archives (topic
is "free bootmem feedback patch").
So there are several changes improve the bootmem freeing, in which the
most basic idea is freeing higher order pages. And as Matthew says,
"Itanium CPUs of this era had no prefetchers."
I did 10 round bootup tests before and after this change, the data doesn't
prove prefetchw() help speeding up bootmem freeing. The sum of the 10
round bootmem freeing time after prefetchw() removal even 5.2% faster than
before.
Link: https://lkml.kernel.org/r/20240702020931.7061-1-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Suggested-by: Matthew Wilcox <willy@infradead.org> Reviewed-by: Matthew Wilcox <willy@infradead.org> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Wei Yang [Mon, 1 Jul 2024 01:34:09 +0000 (01:34 +0000)]
kernel/fork.c: get totalram_pages from memblock to calculate max_threads
Since we plan to move the accounting into __free_pages_core(),
totalram_pages may not represent the total usable pages on system at this
point when defer_init is enabled.
Instead we can get the total usable pages from memblock directly.
Link: https://lkml.kernel.org/r/20240701013410.17260-1-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Johannes Weiner [Mon, 1 Jul 2024 15:31:15 +0000 (11:31 -0400)]
mm: remove CONFIG_MEMCG_KMEM
CONFIG_MEMCG_KMEM used to be a user-visible option for whether slab
tracking is enabled. It has been default-enabled and equivalent to
CONFIG_MEMCG for almost a decade. We've only grown more kernel memory
accounting sites since, and there is no imaginable cgroup usecase going
forward that wants to track user pages but not the multitude of
user-drivable kernel allocations.
Link: https://lkml.kernel.org/r/20240701153148.452230-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Acked-by: David Hildenbrand <david@redhat.com> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Roman Gushchin [Mon, 1 Jul 2024 18:59:32 +0000 (18:59 +0000)]
mm: memcg: add cache line padding to mem_cgroup_per_node
Memcg v1-specific fields serve a buffer function between read-mostly and
update often parts of the mem_cgroup_per_node structure. If
CONFIG_MEMCG_V1 is not set and these fields are not present, an explicit
cacheline padding is needed.
Link: https://lkml.kernel.org/r/20240701185932.704807-2-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Suggested-by: Shakeel Butt <shakeel.butt@linux.dev> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Roman Gushchin [Mon, 1 Jul 2024 18:59:31 +0000 (18:59 +0000)]
mm: memcg: drop obsolete cache line padding in struct mem_cgroup
After the grouping of the cgroup v1-related fields and the corresponding
reorganization of the struct mem_cgroup, the existing cache line padding
doesn't make much sense anymore. Let's drop it for now and put back to
new places, if necessary.
Link: https://lkml.kernel.org/r/20240701185932.704807-1-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Suggested-by: Shakeel Butt <shakeel.butt@linux.dev> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Mon, 1 Jul 2024 19:27:05 +0000 (12:27 -0700)]
Docs/mm/damon/index: add links to design
DAMON subsystem documents index page provides a short intro of DAMON core
concepts. Add links to sections of the design document to let users
easily browse to the details.
SeongJae Park [Mon, 1 Jul 2024 19:27:04 +0000 (12:27 -0700)]
Docs/mm/damon/design: add links to sections of DAMON sysfs interface usage doc
Readers of the design document would wonder how they can configure and use
specific DAMON features. Add links to sections of DAMON sysfs interface
usage document that provides the answers for easier browsing.
SeongJae Park [Mon, 1 Jul 2024 19:27:03 +0000 (12:27 -0700)]
Docs/mm/damon/design: remove 'Programmable Modules' section in favor of 'Modules' section
'Programmable Modules' section provides high level descriptions of the
DAMON API-based kernel modules layer. But 'Modules' section, which is at
the end of the document, provides every detail about the layer including
that of 'Programmable Modules' section.
Since the brief summary of the layers at the beginning of the document has
a link to the 'Modules' section, browsing to the section is not that
difficult. Remove 'Programmable Modules' section in favor of 'Modules'
section and reducing duplicates.
SeongJae Park [Mon, 1 Jul 2024 19:27:02 +0000 (12:27 -0700)]
Docs/mm/damon/design: move 'Configurable Operations Set' section into 'Operations Set Layer' section
'Configurable Operations Set' section is for providing a description of
the pluggability of the operations set layer. Just after that,
'Operations Set Layer' section, which is dedicated for the entire things
of the layer, follows. The layout is odd, and some descriptions are
duplicated. Move 'Configurable Operations Set' section into 'Operations
Set Layer' and re-write some of the detailed descriptions.
SeongJae Park [Mon, 1 Jul 2024 19:27:01 +0000 (12:27 -0700)]
Docs/mm/damon/design: add links from overall architecture to sections of details
DAMON design document briefly explains the overall layers architecture
first, and then provides detailed explanations of each layer with
dedicated sections. Letting readers go directly to the detailed sections
for specific layers could help easy browsing of the not-very-short
document. Add links from the overall summary to the sections of details.
SeongJae Park [Mon, 1 Jul 2024 19:27:00 +0000 (12:27 -0700)]
Docs/admin-guide/mm/damon/start: add access pattern snapshot example
DAMON user-space tool (damo) provides access pattern snapshot feature,
which is expected to be frequently used for real time access pattern
analysis. The snapshot output is also showing what DAMON provides on its
own, including the 'age' information.
In contrast, the recorded access patterns, which is shown as an example
usage on the quick start section, shows what users can make from what
DAMON provided. It includes information that generated outside of DAMON
and makes the 'age' concept bit unclear. Hence snapshot output is easier
at understanding the raw realtime output of DAMON. Add the snapshot usage
example on the quick start section.
SeongJae Park [Mon, 1 Jul 2024 19:26:59 +0000 (12:26 -0700)]
Docs/mm/damon/design: clarify regions merging operation
DAMON design document is not explaining how min_nr_regions limit is kept,
and what happens if the number of regions exceeds max_nr_regions. Add
more clarification for those.
SeongJae Park [Mon, 1 Jul 2024 19:26:58 +0000 (12:26 -0700)]
Docs/mm/damon/design: fix two typos
Patch series "Docs/damon: minor fixups and improvements".
Fixup typos, clarify regions merging operation design with recent change,
add access pattern snapshot example use case, and improve readability of
the design document and subsystem documents index by
reorganizing/wordsmithing and adding links to other sections and/or
documents for easy browsing.
This patch (of 9):
Fix two typos. The first one is just a simple typo: s/accurach/accuracy/
The second one is made by the author being out of their mind. 'Region
Based Sampling' section of the doc is mistakenly calling the access
frequency counter of region as 'nr_regions'. Fix it with the correct
name, 'nr_accesses'.
Bang Li [Fri, 28 Jun 2024 03:23:27 +0000 (11:23 +0800)]
mm/shmem: fix input and output inconsistencies
Commit 19eaf44954df ("mm: thp: support allocation of anonymous multi-size
THP") added mTHP support for anonymous shmem. We can configure different
policies through the multi-size THP sysfs interface for anonymous shmem.
But when we configure the "advise" policy of
/sys/kernel/mm/transparent_hugepage/hugepages-xxxkB/shmem_enabled, we
cannot write the "advise", but write the "madvise", which is unreasonable.
We should keep the output and input values consistent, which is more
convenient for users.
Link: https://lkml.kernel.org/r/20240628032327.16987-1-libang.li@antgroup.com Fixes: 61a57f1b1da9 ("mm: shmem: add multi-size THP sysfs interface for anonymous shmem") Signed-off-by: Bang Li <libang.li@antgroup.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Bang Li <libang.li@antgroup.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Edward Liaw [Tue, 25 Jun 2024 22:34:45 +0000 (22:34 +0000)]
selftests: centralize -D_GNU_SOURCE= to CFLAGS in lib.mk
Centralize the _GNU_SOURCE definition to CFLAGS in lib.mk. Remove
redundant defines from Makefiles that import lib.mk. Convert any usage of
"#define _GNU_SOURCE 1" to "#define _GNU_SOURCE".
This uses the form "-D_GNU_SOURCE=", which is equivalent to
"#define _GNU_SOURCE".
Otherwise using "-D_GNU_SOURCE" is equivalent to "-D_GNU_SOURCE=1" and
"#define _GNU_SOURCE 1", which is less commonly seen in source code and
would require many changes in selftests to avoid redefinition warnings.
Link: https://lkml.kernel.org/r/20240625223454.1586259-2-edliaw@google.com Signed-off-by: Edward Liaw <edliaw@google.com> Suggested-by: John Hubbard <jhubbard@nvidia.com> Acked-by: Shuah Khan <skhan@linuxfoundation.org> Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: André Almeida <andrealmeid@igalia.com> Cc: Darren Hart <dvhart@infradead.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: David S. Miller <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Jarkko Sakkinen <jarkko@kernel.org> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Kees Cook <kees@kernel.org> Cc: Kevin Tian <kevin.tian@intel.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paolo Abeni <pabeni@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Reinette Chatre <reinette.chatre@intel.com> Cc: Sean Christopherson <seanjc@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Barry Song [Sat, 22 Jun 2024 07:12:31 +0000 (19:12 +1200)]
tools/mm: introduce a tool to assess swap entry allocation for thp_swapout
Both Ryan and Chris have been utilizing the small test program to aid in
debugging and identifying issues with swap entry allocation. While a real
or intricate workload might be more suitable for assessing the correctness
and effectiveness of the swap allocation policy, a small test program
presents a simpler means of understanding the problem and initially
verifying the improvements being made.
Let's endeavor to integrate it into tools/mm. Although it presently only
accommodates 64KB and 4KB, I'm optimistic that we can expand its
capabilities to support multiple sizes and simulate more complex systems
in the future as required.
Basically, we have
1. Use MADV_PAGEPUT for rapid swap-out, putting the swap allocation
code under high exercise in a short time.
2. Use MADV_DONTNEED to simulate the behavior of libc and Java heap in
freeing memory, as well as for munmap, app exits, or OOM killer
scenarios. This ensures new mTHP is always generated, released or
swapped out, similar to the behavior on a PC or Android phone where
many applications are frequently started and terminated.
3. Swap in with or without the "-a" option to observe how fragments
due to swap-in and the incoming swap-in of large folios will impact
swap-out fallback.
Due to 2, we ensure a certain proportion of mTHP. Similarly, because of
3, we maintain a certain proportion of small folios, as we don't support
large folios swap-in, meaning any swap-in will immediately result in small
folios. Therefore, with both 2 and 3, we automatically achieve a system
containing both mTHP and small folios. Additionally, 1 provides the
ability to continuously swap them out.
We can also use "-s" to add a dedicated small folios memory area.
[akpm@linux-foundation.org: thp_swap_allocator_test.c needs mman.h, per Kairui Song] Link: https://lkml.kernel.org/r/20240622071231.576056-2-21cnbao@gmail.com Signed-off-by: Barry Song <v-songbaohua@oppo.com> Acked-by: Chris Li <chrisl@kernel.org> Tested-by: Chris Li <chrisl@kernel.org> Reviewed-by: Ryan Roberts <ryan.roberts@arm.com> Tested-by: Ryan Roberts <ryan.roberts@arm.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kairui Song <kasong@tencent.com> Cc: Kalesh Singh <kaleshsingh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kefeng Wang [Wed, 26 Jun 2024 08:53:28 +0000 (16:53 +0800)]
mm: migrate: remove folio_migrate_copy()
The folio_migrate_copy() is just a wrapper of folio_copy() and
folio_migrate_flags(), it is simple and only aio use it for now, unfold it
and remove folio_migrate_copy().
Link: https://lkml.kernel.org/r/20240626085328.608006-7-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Jane Chu <jane.chu@oracle.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Jiaqi Yan <jiaqiyan@google.com> Cc: Lance Yang <ioworker0@gmail.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kefeng Wang [Wed, 26 Jun 2024 08:53:26 +0000 (16:53 +0800)]
mm: migrate: support poisoned recover from migrate folio
The folio migration is widely used in kernel, memory compaction, memory
hotplug, soft offline page, numa balance, memory demote/promotion, etc,
but once access a poisoned source folio when migrating, the kerenl will
panic.
There is a mechanism in the kernel to recover from uncorrectable memory
errors, ARCH_HAS_COPY_MC, which is already used in other core-mm paths,
eg, CoW, khugepaged, coredump, ksm copy, see copy_mc_to_{user,kernel},
copy_mc_{user_}highpage callers.
In order to support poisoned folio copy recover from migrate folio, we
chose to make folio migration tolerant of memory failures and return error
for folio migration, because folio migration is no guarantee of success,
this could avoid the similar panic shown below.
Note, folio copy is moved in the begin of the __migrate_folio(), which
could simplify the error handling since there is no turning back if
folio_migrate_mapping() return success, the downside is the folio copied
even though folio_migrate_mapping() return fail, an optimization is to
check whether source folio does not have extra refs before we do folio
copy.
Link: https://lkml.kernel.org/r/20240626085328.608006-5-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jane Chu <jane.chu@oracle.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Jiaqi Yan <jiaqiyan@google.com> Cc: Lance Yang <ioworker0@gmail.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>