Rafael Aquini [Tue, 24 Aug 2021 00:00:04 +0000 (10:00 +1000)]
ipc: replace costly bailout check in sysvipc_find_ipc()
sysvipc_find_ipc() was left with a costly way to check if the offset
position fed to it is bigger than the total number of IPC IDs in use. So
much so that the time it takes to iterate over /proc/sysvipc/* files grows
exponentially for a custom benchmark that creates "N" SYSV shm segments
and then times the read of /proc/sysvipc/shm (milliseconds):
12 msecs to read 1024 segs from /proc/sysvipc/shm
18 msecs to read 2048 segs from /proc/sysvipc/shm
65 msecs to read 4096 segs from /proc/sysvipc/shm
325 msecs to read 8192 segs from /proc/sysvipc/shm
1303 msecs to read 16384 segs from /proc/sysvipc/shm
5182 msecs to read 32768 segs from /proc/sysvipc/shm
The root problem lies with the loop that computes the total amount of ids
in use to check if the "pos" feeded to sysvipc_find_ipc() grew bigger than
"ids->in_use". That is a quite inneficient way to get to the maximum
index in the id lookup table, specially when that value is already
provided by struct ipc_ids.max_idx.
This patch follows up on the optimization introduced via commit 15df03c879836 ("sysvipc: make get_maxid O(1) again") and gets rid of the
aforementioned costly loop replacing it by a simpler checkpoint based on
ipc_get_maxidx() returned value, which allows for a smooth linear increase
in time complexity for the same custom benchmark:
2 msecs to read 1024 segs from /proc/sysvipc/shm
2 msecs to read 2048 segs from /proc/sysvipc/shm
4 msecs to read 4096 segs from /proc/sysvipc/shm
9 msecs to read 8192 segs from /proc/sysvipc/shm
19 msecs to read 16384 segs from /proc/sysvipc/shm
39 msecs to read 32768 segs from /proc/sysvipc/shm
Link: https://lkml.kernel.org/r/20210809203554.1562989-1-aquini@redhat.com Signed-off-by: Rafael Aquini <aquini@redhat.com> Acked-by: Davidlohr Bueso <dbueso@suse.de> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Waiman Long <llong@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Lukas Bulwahn [Tue, 24 Aug 2021 00:00:04 +0000 (10:00 +1000)]
Kconfig.debug: drop selecting non-existing HARDLOCKUP_DETECTOR_ARCH
Commit 05a4a9527931 ("kernel/watchdog: split up config options") adds a
new config HARDLOCKUP_DETECTOR, which selects the non-existing config
HARDLOCKUP_DETECTOR_ARCH.
Zenghui Yu [Tue, 24 Aug 2021 00:00:03 +0000 (10:00 +1000)]
configs: remove the obsolete CONFIG_INPUT_POLLDEV
This CONFIG option was removed in commit 278b13ce3a89 ("Input: remove
input_polled_dev implementation") so there's no point to keep it in
defconfigs any longer.
Get rid of the leftover for all arches.
Link: https://lkml.kernel.org/r/20210726074741.1062-1-yuzenghui@huawei.com Signed-off-by: Zenghui Yu <yuzenghui@huawei.com> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cyrill Gorcunov [Tue, 24 Aug 2021 00:00:03 +0000 (10:00 +1000)]
prctl: allow to setup brk for et_dyn executables
Keno Fischer reported that when a binray loaded via ld-linux-x the
prctl(PR_SET_MM_MAP) doesn't allow to setup brk value because it lays
before mm:end_data.
This of course prevent criu from restoring such programs. Looking into
how kernel operates with brk/start_brk inside brk() syscall I don't see
any problem if we allow to setup brk/start_brk without checking for
end_data. Even if someone pass some weird address here on a purpose then
the worst possible result will be an unexpected unmapping of existing vma
(own vma, since prctl works with the callers memory) but test for
RLIMIT_DATA is still valid and a user won't be able to gain more memory in
case of expanding VMAs via new values shipped with prctl call.
Link: https://lkml.kernel.org/r/20210121221207.GB2174@grain Fixes: bbdc6076d2e5 ("binfmt_elf: move brk out of mmap when doing direct loader exec") Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> Reported-by: Keno Fischer <keno@juliacomputing.com> Acked-by: Andrey Vagin <avagin@gmail.com> Tested-by: Andrey Vagin <avagin@gmail.com> Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com> Cc: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Takahiro Itazuri [Tue, 24 Aug 2021 00:00:03 +0000 (10:00 +1000)]
pid: cleanup the stale comment mentioning pidmap_init().
pidmap_init() has already been replaced with pid_idr_init() in the commit 95846ecf9dac ("pid: replace pid bitmap implementation with IDR API").
Cleanup the stale comment which still mentions it.
Link: https://lkml.kernel.org/r/20210714120713.19825-1-itazur@amazon.com Signed-off-by: Takahiro Itazuri <itazur@amazon.com> Cc: Kuniyuki Iwashima <kuniyu@amazon.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: David Oberhollenzer <david.oberhollenzer@sigma-star.at> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
David Oberhollenzer [Tue, 24 Aug 2021 00:00:02 +0000 (10:00 +1000)]
fs/coredump.c: log if a core dump is aborted due to changed file permissions
For obvious security reasons, a core dump is aborted if the filesystem
cannot preserve ownership or permissions of the dump file.
This affects filesystems like e.g. vfat, but also something like a 9pfs
share in a Qemu test setup, running as a regular user, depending on the
security model used. In those cases, the result is an empty core file and
a confused user.
To hopefully safe other people a lot of time figuring out the cause, this
patch adds a simple log message for those specific cases.
Gustavo A. R. Silva [Tue, 24 Aug 2021 00:00:02 +0000 (10:00 +1000)]
hfsplus: fix out-of-bounds warnings in __hfsplus_setxattr
Fix the following out-of-bounds warnings by enclosing structure members
file and finder into new struct info:
fs/hfsplus/xattr.c:300:5: warning: 'memcpy' offset [65, 80] from the object at 'entry' is out of the bounds of referenced subobject 'user_info' with type 'struct DInfo' at offset 48 [-Warray-bounds]
fs/hfsplus/xattr.c:313:5: warning: 'memcpy' offset [65, 80] from the object at 'entry' is out of the bounds of referenced subobject 'user_info' with type 'struct FInfo' at offset 48 [-Warray-bounds]
Refactor the code by making it more "structured."
Also, this helps with the ongoing efforts to enable -Warray-bounds and
makes the code clearer and avoid confusing the compiler.
Matthew said:
: The offending line is this:
:
: - memcpy(&entry.file.user_info, value,
: + memcpy(&entry.file.info, value,
: file_finderinfo_len);
:
: what it's trying to do is copy two structs which are adjacent to each
: other in a single call to memcpy(). gcc legitimately complains that
: the memcpy to this struct overruns the bounds of the struct. What
: Gustavo has done here is introduce a new struct that contains the two
: structs, and now gcc is happy that the memcpy doesn't overrun the
: length of this containing struct.
Nanyong Sun [Tue, 24 Aug 2021 00:00:02 +0000 (10:00 +1000)]
nilfs2: fix memory leak in nilfs_sysfs_delete_snapshot_group
kobject_put() should be used to cleanup the memory associated with the
kobject instead of kobject_del(). See the section "Kobject removal" of
"Documentation/core-api/kobject.rst".
Nanyong Sun [Tue, 24 Aug 2021 00:00:02 +0000 (10:00 +1000)]
nilfs2: fix memory leak in nilfs_sysfs_create_snapshot_group
If kobject_init_and_add returns with error, kobject_put() is needed here
to avoid memory leak, because kobject_init_and_add may return error
without freeing the memory associated with the kobject it allocated.
Nanyong Sun [Tue, 24 Aug 2021 00:00:02 +0000 (10:00 +1000)]
nilfs2: fix memory leak in nilfs_sysfs_delete_##name##_group
The kobject_put() should be used to cleanup the memory associated with the
kobject instead of kobject_del. See the section "Kobject removal" of
"Documentation/core-api/kobject.rst".
Nanyong Sun [Tue, 24 Aug 2021 00:00:01 +0000 (10:00 +1000)]
nilfs2: fix memory leak in nilfs_sysfs_create_##name##_group
If kobject_init_and_add return with error, kobject_put() is needed here to
avoid memory leak, because kobject_init_and_add may return error without
freeing the memory associated with the kobject it allocated.
Nanyong Sun [Tue, 24 Aug 2021 00:00:01 +0000 (10:00 +1000)]
nilfs2: fix NULL pointer in nilfs_##name##_attr_release
In nilfs_##name##_attr_release, kobj->parent should not be referenced
because it is a NULL pointer. The release() method of kobject is always
called in kobject_put(kobj), in the implementation of kobject_put(), the
kobj->parent will be assigned as NULL before call the release() method.
So just use kobj to get the subgroups, which is more efficient and can fix
a NULL pointer reference problem.
Nanyong Sun [Tue, 24 Aug 2021 00:00:01 +0000 (10:00 +1000)]
nilfs2: fix memory leak in nilfs_sysfs_create_device_group
Patch series "nilfs2: fix incorrect usage of kobject".
This patchset from Nanyong Sun fixes memory leak issues and a NULL pointer
dereference issue caused by incorrect usage of kboject in nilfs2 sysfs
implementation.
If kobject_init_and_add return with error, then the cleanup of kobject is
needed because memory may be allocated in kobject_init_and_add without
freeing.
And the place of cleanup_dev_kobject should use kobject_put to free the
memory associated with the kobject. As the section "Kobject removal" of
"Documentation/core-api/kobject.rst" says, kobject_del() just makes the
kobject "invisible", but it is not cleaned up. And no more cleanup will
do after cleanup_dev_kobject, so kobject_put is needed here.
Andrew Halaney [Tue, 24 Aug 2021 00:00:01 +0000 (10:00 +1000)]
init/main.c: silence some -Wunused-parameter warnings
There are a bunch of callbacks with unused arguments, go ahead and silence
those so "make KCFLAGS=-W init/main.o" is a little quieter. Here's a
little sample:
Kefeng Wang [Tue, 24 Aug 2021 00:00:01 +0000 (10:00 +1000)]
trap: cleanup trap_init()
There are some empty trap_init() definitions in different ARCHs, Introduce
a new weak trap_init() function to clean them up.
Link: https://lkml.kernel.org/r/20210812123602.76356-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> [arm32] Acked-by: Vineet Gupta <vgupt@kernel.org> [arc] Acked-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc] Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Ley Foon Tan <ley.foon.tan@intel.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> Cc: Stafford Horne <shorne@gmail.com> Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com> Cc: Helge Deller <deller@gmx.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <palmerdabbelt@google.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Rasmus Villemoes [Tue, 24 Aug 2021 00:00:00 +0000 (10:00 +1000)]
init: move usermodehelper_enable() to populate_rootfs()
Currently, usermodehelper is enabled right before PID1 starts going
through the initcalls. However, any call of a usermodehelper from a
pure_, core_, postcore_, arch_, subsys_ or fs_ initcall is futile, as
there is no filesystem contents yet.
Up until commit e7cb072eb988 ("init/initramfs.c: do unpacking
asynchronously"), such calls, whether via some request_module(), a
legacy uevent "/sbin/hotplug" notification or something else, would
just fail silently with (presumably) -ENOENT from
kernel_execve(). However, that commit introduced the
wait_for_initramfs() synchronization hook which must be called from
the usermodehelper exec path right before the kernel_execve, in order
that request_module() et al done from *after* rootfs_initcall()
time (i.e. device_ and late_ initcalls) would continue to find a
populated initramfs as they used to.
Any call of wait_for_initramfs() done before the unpacking has been
scheduled (i.e. before rootfs_initcall time) must just return
immediately [and let the caller find an empty file system] in order
not to deadlock the machine. I mistakenly thought, and my limited
testing confirmed, that there were no such calls, so I added a
pr_warn_once() in wait_for_initramfs(). It turns out that one can
indeed hit request_module() as well as kobject_uevent_env() during
those early init calls, leading to a user-visible warning in the
kernel log emitted consistently for certain configurations.
We could just remove the pr_warn_once(), but I think it's better to
postpone enabling the usermodehelper framework until there is at least
some chance of finding the executable. That is also a little more
efficient in that a lot of work done in umh.c will be elided. However,
it does change the error seen by those early callers from -ENOENT to
-EBUSY, so there is a risk of a regression if any caller care about
the exact error value.
Link: https://lkml.kernel.org/r/20210728134638.329060-1-linux@rasmusvillemoes.dk Fixes: e7cb072eb988 ("init/initramfs.c: do unpacking asynchronously") Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reported-by: Alexander Egorenkov <egorenar@linux.ibm.com> Reported-by: Bruno Goncalves <bgoncalv@redhat.com> Reported-by: Heiner Kallweit <hkallweit1@gmail.com> Cc: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
yangerkun [Tue, 24 Aug 2021 00:00:00 +0000 (10:00 +1000)]
ramfs: fix mount source show for ramfs
ramfs_parse_param does not parse the key "source", and will convert
-ENOPARAM to 0. This will skip calling vfs_parse_fs_param_source() in
vfs_parse_fs_param(), which leads to always presenting "none" as the mount
source for ramfs. Fix it by parsing "source" in ramfs_parse_param().
Link: https://lkml.kernel.org/r/20210811122811.2288041-1-yangerkun@huawei.com Signed-off-by: yangerkun <yangerkun@huawei.com> Cc: Jan Kara <jack@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Yu Kuai <yukuai3@huawei.com> Cc: ErKun Yang <yangerkun@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lkml.kernel.org/r/20210804191421.GA1900577@roeck-us.net Cc: Guenter Roeck <linux@roeck-us.net> Cc: Mark Brown <broonie@kernel.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
fix build errors in kernel/user.c when CONFIG_EPOLL=n
Also fix typo: "cpunter" -"counter" in a panic message.
[npiggin@gmail.com: move ifdefs into wrapper functions, slightly improve panic message] Link: https://lkml.kernel.org/r/1628051945.fens3r99ox.astroid@bobo.none Fixes: e75b89477811 ("fs/epoll: use a per-cpu counter for user's watches count") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Cc: Mark Brown <broonie@kernel.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Nicholas Piggin [Tue, 24 Aug 2021 00:00:00 +0000 (10:00 +1000)]
fs/epoll: use a per-cpu counter for user's watches count
This counter tracks the number of watches a user has, to compare against
the 'max_user_watches' limit. This causes a scalability bottleneck on
SPECjbb2015 on large systems as there is only one user. Changing to a
per-cpu counter increases throughput of the benchmark by about 30% on a
16-socket, > 1000 thread system.
Link: https://lkml.kernel.org/r/20210802032013.2751916-1-npiggin@gmail.com Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reported-by: Anton Blanchard <anton@ozlabs.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Joe Perches [Mon, 23 Aug 2021 23:59:59 +0000 (09:59 +1000)]
checkpatch: improve GIT_COMMIT_ID test
The preferred git commit id reference has the form
commit <SHA-1> ("Title line")
where SHA-1 is the commit hex hash with a minimum lenth of 12 and ("Title
line") is the complete title line of the commit with a (" prefix and ")
suffix.
The current tests fail when the "Title line" has one or more embedded
double quotes.
Improve the test that finds the commit SHA-1 hex hash then ("Title line")
by using $balanced_parens for a maximum of 3 consecutive lines.
Link: https://lkml.kernel.org/r/976c6cdd680db4b55ae31b5fc2d1779da5c0dc66.camel@perches.com Signed-off-by: Joe Perches <joe@perches.com> Cc: Dwaipayan Ray <dwaipayanray1@gmail.com> Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com> Cc: Denis Efremov <efremov@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Mimi Zohar [Mon, 23 Aug 2021 23:59:59 +0000 (09:59 +1000)]
checkpatch: make email address check case insensitive
Instead of checkpatch requiring the patch author to exactly match the
signed-off-by tag, commit 48ca2d8ac8a1 ("checkpatch: add new warnings to
author signoff checks.") safely relaxed this requirement.
Although the local-part of an email address (local-part@domain), may be
case sensitive, exploiting the case sensitivity of mailbox local-parts
impedes interoperability and is discouraged. Mailbox domains follow
normal DNS rules and are hence not case sensitive. (Refer to
https://datatracker.ietf.org/doc/html/rfc5321#section-2.4.)
Further relax the patch author and signed-off-by tag comparison by making
the email address check case insensitive.
Yury Norov [Mon, 23 Aug 2021 23:59:58 +0000 (09:59 +1000)]
vsprintf: rework bitmap_list_string
bitmap_list_string() is very ineffective when printing bitmaps with long
ranges of set bits because it calls find_next_bit for each bit in the
bitmap. We can do better by detecting ranges of set bits.
In my environment, before/after is 943008/31008 ns.
Link: https://lkml.kernel.org/r/20210814211713.180533-18-yury.norov@gmail.com Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Cc: Alexander Lobakin <alobakin@pm.me> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Yury Norov [Mon, 23 Aug 2021 23:59:58 +0000 (09:59 +1000)]
bitmap: unify find_bit operations
bitmap_for_each_{set,clear}_region() are similar to for_each_bit() macros
in include/linux/find.h, but interface and implementation of them are
different.
This patch adds for_each_bitrange() macros and drops unused
bitmap_*_region() API in sake of unification.
Link: https://lkml.kernel.org/r/20210814211713.180533-16-yury.norov@gmail.com Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Dennis Zhou <dennis@kernel.org> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> [MMC] Cc: Alexander Lobakin <alobakin@pm.me> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Yury Norov [Mon, 23 Aug 2021 23:59:58 +0000 (09:59 +1000)]
mm/percpu: micro-optimize pcpu_is_populated()
bitmap_next_clear_region() calls find_next_zero_bit() and find_next_bit()
sequentially to find a range of clear bits. In case of
pcpu_is_populated() there's a chance to return earlier if bitmap has all
bits set.
Link: https://lkml.kernel.org/r/20210814211713.180533-15-yury.norov@gmail.com Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Alexander Lobakin <alobakin@pm.me> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Yury Norov [Mon, 23 Aug 2021 23:59:57 +0000 (09:59 +1000)]
cpumask: replace cpumask_next_* with cpumask_first_* where appropriate
cpumask_first() is a more effective analogue of 'next' version if n == -1
(which means start == 0). This patch replaces 'next' with 'first' where
things look trivial.
There's no cpumask_first_zero() function, so create it.
Link: https://lkml.kernel.org/r/20210814211713.180533-10-yury.norov@gmail.com Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Cc: Alexander Lobakin <alobakin@pm.me> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Yury Norov [Mon, 23 Aug 2021 23:59:57 +0000 (09:59 +1000)]
tools: sync tools/bitmap with mother linux
Remove tools/include/asm-generic/bitops/find.h and copy
include/linux/bitmap.h to tools. find_*_le() functions are not copied
because not needed in tools.
Link: https://lkml.kernel.org/r/20210814211713.180533-9-yury.norov@gmail.com Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Cc: Alexander Lobakin <alobakin@pm.me> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Yury Norov [Mon, 23 Aug 2021 23:59:56 +0000 (09:59 +1000)]
all: replace find_next{,_zero}_bit with find_first{,_zero}_bit where appropriate
find_first{,_zero}_bit is a more effective analogue of 'next' version if
start == 0. This patch replaces 'next' with 'first' where things look
trivial.
Link: https://lkml.kernel.org/r/20210814211713.180533-8-yury.norov@gmail.com Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Cc: Alexander Lobakin <alobakin@pm.me> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Yury Norov [Mon, 23 Aug 2021 23:59:56 +0000 (09:59 +1000)]
lib: add find_first_and_bit()
Currently find_first_and_bit() is an alias to find_next_and_bit().
However, it is widely used in cpumask, so it worth to optimize it. This
patch adds its own implementation for find_first_and_bit().
Yury Norov [Mon, 23 Aug 2021 23:59:56 +0000 (09:59 +1000)]
arch: remove GENERIC_FIND_FIRST_BIT entirely
In 5.12 cycle we enabled GENERIC_FIND_FIRST_BIT config option for ARM64
and MIPS. It increased performance and shrunk .text size; and so far I
didn't receive any negative feedback on the change.
Now I think it's a good time to switch all architectures to use
find_{first,last}_bit() unconditionally, and so remove corresponding
config option.
The patch does't introduce functioal changes for arc, arm, arm64, mips,
m68k, s390 and x86, for other architectures I expect improvement both in
performance and .text size.
Link: https://lkml.kernel.org/r/20210814211713.180533-5-yury.norov@gmail.com Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Alexander Lobakin <alobakin@pm.me> (mips) Reviewed-by: Alexander Lobakin <alobakin@pm.me> (mips) Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Will Deacon <will@kernel.org> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Yury Norov [Mon, 23 Aug 2021 23:59:56 +0000 (09:59 +1000)]
include: move find.h from asm_generic to linux
find_bit API and bitmap API are closely related, but inclusion paths are
different - include/asm-generic and include/linux, correspondingly. In
the past it made a lot of troubles due to circular dependencies and/or
undefined symbols. Fix this by moving find.h under include/linux.
Link: https://lkml.kernel.org/r/20210814211713.180533-4-yury.norov@gmail.com Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Cc: Alexander Lobakin <alobakin@pm.me> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Yury Norov [Mon, 23 Aug 2021 23:59:55 +0000 (09:59 +1000)]
bitops: protect find_first_{,zero}_bit properly
Patch series "Resend bitmap patches".
This patch (of 17):
find_first_bit() and find_first_zero_bit() are not protected with ifdefs
as other functions in find.h. It causes build errors on some platforms if
CONFIG_GENERIC_FIND_FIRST_BIT is enabled.
Link: https://lkml.kernel.org/r/20210814211713.180533-1-yury.norov@gmail.com Link: https://lkml.kernel.org/r/20210814211713.180533-2-yury.norov@gmail.com Fixes: 2cc7b6a44ac2 ("lib: add fast path for find_first_*_bit() and find_last_bit()") Signed-off-by: Yury Norov <yury.norov@gmail.com> Reported-by: kernel test robot <lkp@intel.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Cc: Alexander Lobakin <alobakin@pm.me> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Randy Dunlap [Mon, 23 Aug 2021 23:59:55 +0000 (09:59 +1000)]
lib/iov_iter.c: fix kernel-doc warnings
Fix all kernel-doc warnings in lib/iov_iter.c:
lib/iov_iter.c:695: warning: Function parameter or member 'i' not described in '_copy_mc_to_iter'
lib/iov_iter.c:695: warning: Excess function parameter 'iter' description in '_copy_mc_to_iter'
lib/iov_iter.c:695: warning: No description found for return value of '_copy_mc_to_iter'
lib/iov_iter.c:758: warning: Function parameter or member 'i' not described in '_copy_from_iter_flushcache'
lib/iov_iter.c:758: warning: Excess function parameter 'iter' description in '_copy_from_iter_flushcache'
lib/iov_iter.c:758: warning: No description found for return value of '_copy_from_iter_flushcache'
Link: https://lkml.kernel.org/r/20210809051053.6531-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Randy Dunlap [Mon, 23 Aug 2021 23:59:55 +0000 (09:59 +1000)]
lib/dump_stack: correct kernel-doc notation
Fix kernel-doc warnings in dump_stack.c:
lib/dump_stack.c:97: warning: Function parameter or member 'log_lvl' not described in 'dump_stack_lvl'
lib/dump_stack.c:97: warning: expecting prototype for dump_stack(). Prototype was for dump_stack_lvl() instead
Link: https://lkml.kernel.org/r/20210809051643.17567-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Matteo Croce [Mon, 23 Aug 2021 23:59:54 +0000 (09:59 +1000)]
lib/string: optimized memset
The generic memset is defined as a byte at time write. This is always
safe, but it's slower than a 4 byte or even 8 byte write.
Write a generic memset which fills the data one byte at time until the
destination is aligned, then fills using the largest size allowed, and
finally fills the remaining data one byte at time.
On a RISC-V machine the speed goes from 140 Mb/s to 241 Mb/s, and this the
binary size increase according to bloat-o-meter:
Function old new delta
memset 32 148 +116
Link: https://lkml.kernel.org/r/20210702123153.14093-4-mcroce@linux.microsoft.com Signed-off-by: Matteo Croce <mcroce@microsoft.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: David Laight <David.Laight@aculab.com> Cc: Drew Fustini <drew@beagleboard.org> Cc: Emil Renner Berthing <kernel@esmil.dk> Cc: Guo Ren <guoren@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Nick Kossifidis <mick@ics.forth.gr> Cc: Palmer Dabbelt <palmer@dabbelt.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Matteo Croce [Mon, 23 Aug 2021 23:59:54 +0000 (09:59 +1000)]
lib/string: optimized memmove
When the destination buffer is before the source one, or when the buffers
doesn't overlap, it's safe to use memcpy() instead, which is optimized to
use a bigger data size possible.
This "optimization" only covers a common case. In future, proper code
which does the same thing as memcpy() does but backwards can be done.
Link: https://lkml.kernel.org/r/20210702123153.14093-3-mcroce@linux.microsoft.com Signed-off-by: Matteo Croce <mcroce@microsoft.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: David Laight <David.Laight@aculab.com> Cc: Drew Fustini <drew@beagleboard.org> Cc: Emil Renner Berthing <kernel@esmil.dk> Cc: Guo Ren <guoren@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Nick Kossifidis <mick@ics.forth.gr> Cc: Palmer Dabbelt <palmer@dabbelt.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Matteo Croce [Mon, 23 Aug 2021 23:59:54 +0000 (09:59 +1000)]
lib/string: optimized memcpy
Patch series "lib/string: optimized mem* functions", v2.
Rewrite the generic mem{cpy,move,set} so that memory is accessed with the
widest size possible, but without doing unaligned accesses.
This was originally posted as C string functions for RISC-V[1], but as
there was no specific RISC-V code, it was proposed for the generic
lib/string.c implementation.
Tested on RISC-V and on x86_64 by undefining __HAVE_ARCH_MEM{CPY,SET,MOVE}
and HAVE_EFFICIENT_UNALIGNED_ACCESS.
These are the performances of memcpy() and memset() of a RISC-V machine on
a 32 mbyte buffer:
memcpy:
original aligned: 75 Mb/s
original unaligned: 75 Mb/s
new aligned: 114 Mb/s
new unaligned: 107 Mb/s
memset:
original aligned: 140 Mb/s
original unaligned: 140 Mb/s
new aligned: 241 Mb/s
new unaligned: 241 Mb/s
The only architecture which will use all the three function will be riscv,
while memmove() will be used by arc, h8300, hexagon, ia64, openrisc and
parisc.
Keep in mind that memmove() isn't anything special, it just calls memcpy()
when possible (e.g. buffers not overlapping), and fallbacks to the byte
by byte copy otherwise.
In future we can write two functions, one which copies forward and another
one which copies backward, and call the right one depending on the buffers
position. Then, we could alias memcpy() and memmove(), as proposed by
Linus: https://bugzilla.redhat.com/show_bug.cgi?id=638477#c132
This patch (of 3):
Rewrite the generic memcpy() to copy a word at time, without generating
unaligned accesses.
The procedure is made of three steps: First copy data one byte at time
until the destination buffer is aligned to a long boundary. Then copy the
data one long at time shifting the current and the next long to compose a
long at every cycle. Finally, copy the remainder one byte at time.
This is the improvement on RISC-V:
original aligned: 75 Mb/s
original unaligned: 75 Mb/s
new aligned: 114 Mb/s
new unaligned: 107 Mb/s
and this the binary size increase according to bloat-o-meter:
Function old new delta
memcpy 36 324 +288
Link: https://lkml.kernel.org/r/20210702123153.14093-1-mcroce@linux.microsoft.com Link: https://lkml.kernel.org/r/20210702123153.14093-2-mcroce@linux.microsoft.com Signed-off-by: Matteo Croce <mcroce@microsoft.com> Cc: Nick Kossifidis <mick@ics.forth.gr> Cc: Guo Ren <guoren@kernel.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: David Laight <David.Laight@aculab.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Emil Renner Berthing <kernel@esmil.dk> Cc: Drew Fustini <drew@beagleboard.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Geert Uytterhoeven [Mon, 23 Aug 2021 23:59:54 +0000 (09:59 +1000)]
math: RATIONAL_KUNIT_TEST should depend on RATIONAL instead of selecting it
RATIONAL_KUNIT_TEST selects RATIONAL, thus enabling an optional feature
the user may not want to have enabled. Fix this by making the test depend
on RATIONAL instead.
Link: https://lkml.kernel.org/r/20210706100945.3803694-3-geert@linux-m68k.org Fixes: b6c75c4afceb8bc0 ("lib/math/rational: add Kunit test cases") Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: Colin Ian King <colin.king@canonical.com> Cc: Trent Piepho <tpiepho@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Geert Uytterhoeven [Mon, 23 Aug 2021 23:59:54 +0000 (09:59 +1000)]
math: make RATIONAL tristate
Patch series "math: RATIONAL and RATIONAL_KUNIT_TEST improvements".
This series makes the RATIONAL symbol tristate, so it is not forced
builtin if all users are modular, and makes the RATIONAL_KUNIT_TEST depend
on RATIONAL, to avoid enabling RATIONAL if there are no real users.
This patch (of 2):
All but one symbols that select RATIONAL are tristate, but RATIONAL itself
is bool. Change it to tristate, so the rational fractions support code
can be modular if no builtin code relies on it.
Yang Yang [Mon, 23 Aug 2021 23:59:53 +0000 (09:59 +1000)]
kernel/acct.c: use dedicated helper to access rlimit values
Use rlimit() helper instead of manually writing whole chain from
task to rlimit value. See patch "posix-cpu-timers: Use dedicated
helper to access rlimit values".
Link: https://lkml.kernel.org/r/20210728030822.524789-1-yang.yang29@zte.com.cn Signed-off-by: Yang Yang <yang.yang29@zte.com.cn> Reported-by: Zeal Robot <zealci@zte.com.cn> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: sh_def@163.com <sh_def@163.com> Cc: Yang Yang <yang.yang29@zte.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Daniel Lezcano [Mon, 23 Aug 2021 23:59:52 +0000 (09:59 +1000)]
units: change from 'L' to 'UL'
Patch series "Add Hz macros", v3.
There are multiple definitions of the HZ_PER_MHZ or HZ_PER_KHZ in the
different drivers. Instead of duplicating this definition again and
again, add one in the units.h header to be reused in all the place the
redefiniton occurs.
At the same time, change the type of the Watts, as they can not be
negative.
This patch (of 10):
The users of the macros are safe to be assigned with an unsigned instead
of signed as the variables using them are themselves unsigned.
Link: https://lkml.kernel.org/r/20210816114732.1834145-1-daniel.lezcano@linaro.org Link: https://lkml.kernel.org/r/20210816114732.1834145-2-daniel.lezcano@linaro.org Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Jonathan Cameron <jic23@kernel.org> Cc: Christian Eggers <ceggers@arri.de> Cc: Lukasz Luba <lukasz.luba@arm.com> Cc: MyungJoo Ham <myungjoo.ham@samsung.com> Cc: Kyungmin Park <kyungmin.park@samsung.com> Cc: Lars-Peter Clausen <lars@metafoo.de> Cc: Peter Meerwald <pmeerw@pmeerw.net> Cc: Zhang Rui <rui.zhang@intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Miquel Raynal <miquel.raynal@bootlin.com> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Chanwoo Choi <cw00.choi@samsung.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Julius Hemanth Pitti [Mon, 23 Aug 2021 23:59:51 +0000 (09:59 +1000)]
proc/sysctl: make protected_* world readable
protected_* files have 600 permissions which prevents non-superuser from
reading them.
Container like "AWS greengrass" refuse to launch unless
protected_hardlinks and protected_symlinks are set. When containers like
these run with "userns-remap" or "--user" mapping container's root to
non-superuser on host, they fail to run due to denied read access to these
files.
As these protections are hardly a secret, and do not possess any security
risk, making them world readable.
Though above greengrass usecase needs read access to only
protected_hardlinks and protected_symlinks files, setting all other
protected_* files to 644 to keep consistency.
Link: http://lkml.kernel.org/r/20200709235115.56954-1-jpitti@cisco.com Fixes: 800179c9b8a1 ("fs: add link restrictions") Signed-off-by: Julius Hemanth Pitti <jpitti@cisco.com> Acked-by: Kees Cook <keescook@chromium.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Ohhoon Kwon [Mon, 23 Aug 2021 23:59:51 +0000 (09:59 +1000)]
connector: send event on write to /proc/[pid]/comm
While comm change event via prctl has been reported to proc connector by
'commit f786ecba4158 ("connector: add comm change event report to proc
connector")', connector listeners were missing comm changes by explicit
writes on /proc/[pid]/comm.
Let explicit writes on /proc/[pid]/comm report to proc connector.
Link: https://lkml.kernel.org/r/20210701133458epcms1p68e9eb9bd0eee8903ba26679a37d9d960@epcms1p6 Signed-off-by: Ohhoon Kwon <ohoono.kwon@samsung.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: David S. Miller <davem@davemloft.net> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Feng Zhou [Mon, 23 Aug 2021 23:59:50 +0000 (09:59 +1000)]
fs/proc/kcore.c: add mmap interface
When we do the kernel monitor, use the DRGN
(https://github.com/osandov/drgn) access to kernel data structures, found
that the system calls a lot. DRGN is implemented by reading /proc/kcore.
After looking at the kcore code, it is found that kcore does not implement
mmap, resulting in frequent context switching triggered by read.
Therefore, we want to add mmap interface to optimize performance. Since
vmalloc and module areas will change with allocation and release,
consistency cannot be guaranteed, so mmap interface only maps KCORE_TEXT
and KCORE_RAM.
The test results:
1. the default version of kcore
real 11.00
user 8.53
sys 3.59
Randy Dunlap [Mon, 23 Aug 2021 23:59:50 +0000 (09:59 +1000)]
alpha: pci-sysfs: fix all kernel-doc warnings
Fix all kernel-doc warnings in arch/alpha/kernel/pci-sysfs.c:
../arch/alpha/kernel/pci-sysfs.c:67: warning: No description found for return value of 'pci_mmap_resource'
../arch/alpha/kernel/pci-sysfs.c:115: warning: Function parameter or member 'pdev' not described in 'pci_remove_resource_files'
../arch/alpha/kernel/pci-sysfs.c:115: warning: Excess function parameter 'dev' description in 'pci_remove_resource_files'
../arch/alpha/kernel/pci-sysfs.c:230: warning: Function parameter or member 'pdev' not described in 'pci_create_resource_files'
../arch/alpha/kernel/pci-sysfs.c:230: warning: Excess function parameter 'dev' description in 'pci_create_resource_files'
../arch/alpha/kernel/pci-sysfs.c:232: warning: No description found for return value of 'pci_create_resource_files'
../arch/alpha/kernel/pci-sysfs.c:305: warning: Function parameter or member 'bus' not described in 'pci_adjust_legacy_attr'
../arch/alpha/kernel/pci-sysfs.c:305: warning: Excess function parameter 'b' description in 'pci_adjust_legacy_attr'
Link: https://lkml.kernel.org/r/20210808185249.31442-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Randy Dunlap [Mon, 23 Aug 2021 23:59:50 +0000 (09:59 +1000)]
alpha: agp: make empty macros use do-while-0 style
Copy these macros from ia64/include/asm/agp.h to avoid the
"empty-body" in 'if' statment warning.
drivers/char/agp/generic.c: In function 'agp_generic_destroy_page':
../drivers/char/agp/generic.c:1265:42: warning: suggest braces around empty body in an 'if' statement [-Wempty-body]
1265 | unmap_page_from_agp(page);
Link: https://lkml.kernel.org/r/20210809030822.20658-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: David Airlie <airlied@linux.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Tetsuo Handa [Mon, 23 Aug 2021 23:59:50 +0000 (09:59 +1000)]
kernel/hung_task.c: Monitor killed tasks.
syzbot's current top report is "no output from test machine" where the
userspace process failed to spawn a new test process for 300 seconds for
some reason. One of reasons which can result in this report is that an
already spawned test process was unable to terminate (e.g. trapped at an
unkillable retry loop due to some bug) after SIGKILL was sent to that
process. Therefore, reporting when a thread is failing to terminate
despite a fatal signal is pending would give us more useful information.
In the context of syzbot's testing where there are only 2 CPUs in the
target VM (which means that only small number of threads and not so much
memory) and threads get SIGKILL after 5 seconds from fork(), being unable
to reach do_exit() within 10 seconds is likely a sign of something went
wrong. Therefore, I would like to try this patch in linux-next.git for
feasibility testing whether this patch helps finding more bugs and
reproducers for such bugs, by bringing "unable to terminate threads"
reports out of "no output from test machine" reports.
Potential bad effect of this patch will be that kernel code becomes
killable without addressing the root cause of being unable to terminate,
for use of killable wait will bypass both TASK_UNINTERRUPTIBLE stall test
and SIGKILL after 5 seconds behavior, which will result in failing to
detect in real systems where SIGKILL won't be sent after 5 seconds when
something went wrong.
This version shares existing sysctl settings (e.g. check interval,
timeout, whether to panic) used for detecting TASK_UNINTERRUPTIBLE
threads. We will likely want to use different sysctl settings for
monitoring killed threads. But let's start as linux-next.git patch
without introducing new sysctl settings. We can add sysctl settings
before sending to linux.git.
Link: http://lkml.kernel.org/r/60d1d7f6-b201-3dcb-a51b-76a31bcfa919@i-love.sakura.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Liu Chuansheng <chuansheng.liu@intel.com> Cc: Valdis Kletnieks <valdis.kletnieks@vt.edu> Cc: linux-kernel@vger.kernel.org Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Tetsuo Handa [Mon, 23 Aug 2021 23:59:49 +0000 (09:59 +1000)]
fs/buffer.c: add debug print for __getblk_gfp() stall problem
Among syzbot's unresolved hung task reports, 18 out of 65 reports contain
__getblk_gfp() line in the backtrace. Since there is a comment block that
says that __getblk_gfp() will lock up the machine if try_to_free_buffers()
attempt from grow_dev_page() is failing, let's start from checking whether
syzbot is hitting that case. This change will be removed after the bug is
fixed.
Link: http://lkml.kernel.org/r/9b9fcdda-c347-53ee-fdbb-8a7d11cf430e@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Jeff Layton <jlayton@redhat.com> Cc: <syzkaller-bugs@googlegroups.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
SeongJae Park [Mon, 23 Aug 2021 23:59:48 +0000 (09:59 +1000)]
mm/damon/dbgfs: support multiple contexts
In some use cases, users would want to run multiple monitoring context.
For example, if a user wants a high precision monitoring and dedicating
multiple CPUs for the job is ok, because DAMON creates one monitoring
thread per one context, the user can split the monitoring target regions
into multiple small regions and create one context for each region. Or,
someone might want to simultaneously monitor different address spaces,
e.g., both virtual address space and physical address space.
The DAMON's API allows such usage, but 'damon-dbgfs' does not. Therefore,
only kernel space DAMON users can do multiple contexts monitoring.
This commit allows the user space DAMON users to use multiple contexts
monitoring by introducing two new 'damon-dbgfs' debugfs files,
'mk_context' and 'rm_context'. Users can create a new monitoring context
by writing the desired name of the new context to 'mk_context'. Then, a
new directory with the name and having the files for setting of the
context ('attrs', 'target_ids' and 'record') will be created under the
debugfs directory. Writing the name of the context to remove to
'rm_context' will remove the related context and directory.
Link: https://lkml.kernel.org/r/20210716081449.22187-10-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Leonard Foerster <foersleo@amazon.de> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
SeongJae Park [Mon, 23 Aug 2021 23:59:47 +0000 (09:59 +1000)]
mm/damon: implement a debugfs-based user space interface
DAMON is designed to be used by kernel space code such as the memory
management subsystems, and therefore it provides only kernel space API.
That said, letting the user space control DAMON could provide some
benefits to them. For example, it will allow user space to analyze their
specific workloads and make their own special optimizations.
For such cases, this commit implements a simple DAMON application kernel
module, namely 'damon-dbgfs', which merely wraps the DAMON api and exports
those to the user space via the debugfs.
'damon-dbgfs' exports three files, ``attrs``, ``target_ids``, and
``monitor_on`` under its debugfs directory, ``<debugfs>/damon/``.
Attributes
----------
Users can read and write the ``sampling interval``, ``aggregation
interval``, ``regions update interval``, and min/max number of monitoring
target regions by reading from and writing to the ``attrs`` file. For
example, below commands set those values to 5 ms, 100 ms, 1,000 ms, 10,
1000 and check it again::
Some types of address spaces supports multiple monitoring target. For
example, the virtual memory address spaces monitoring can have multiple
processes as the monitoring targets. Users can set the targets by writing
relevant id values of the targets to, and get the ids of the current
targets by reading from the ``target_ids`` file. In case of the virtual
address spaces monitoring, the values should be pids of the monitoring
target processes. For example, below commands set processes having pids
42 and 4242 as the monitoring targets and check it again::
Note that setting the target ids doesn't start the monitoring.
Turning On/Off
--------------
Setting the files as described above doesn't incur effect unless you
explicitly start the monitoring. You can start, stop, and check the
current status of the monitoring by writing to and reading from the
``monitor_on`` file. Writing ``on`` to the file starts the monitoring of
the targets with the attributes. Writing ``off`` to the file stops those.
DAMON also stops if every targets are invalidated (in case of the virtual
memory monitoring, target processes are invalidated when terminated).
Below example commands turn on, off, and check the status of DAMON::
# cd <debugfs>/damon
# echo on > monitor_on
# echo off > monitor_on
# cat monitor_on
off
Please note that you cannot write to the above-mentioned debugfs files
while the monitoring is turned on. If you write to the files while DAMON
is running, an error code such as ``-EBUSY`` will be returned.
Link: https://lkml.kernel.org/r/20210716081449.22187-8-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Leonard Foerster <foersleo@amazon.de> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
SeongJae Park [Mon, 23 Aug 2021 23:59:47 +0000 (09:59 +1000)]
mm/damon: add a tracepoint
This commit adds a tracepoint for DAMON. It traces the monitoring results
of each region for each aggregation interval. Using this, DAMON can
easily integrated with tracepoints supporting tools such as perf.
Link: https://lkml.kernel.org/r/20210716081449.22187-7-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Leonard Foerster <foersleo@amazon.de> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Commit 13d49dbd0123 ("mm/damon: implement primitives for the virtual
memory address spaces") of linux-mm[1] makes DAMON_VADDR to set
PAGE_IDLE_FLAG. PAGE_IDLE_FLAG sets PAGE_EXTENSION if !64BIT. However,
DAMON_VADDR do the same work again. This commit removes the unnecessary
duplicate.
Link: https://lkml.kernel.org/r/20210806095153.6444-2-sj38.park@gmail.com Fixes: 13d49dbd0123 ("mm/damon: implement primitives for the virtual memory address spaces") Signed-off-by: SeongJae Park <sjpark@amazon.de> Reported-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
SeongJae Park [Mon, 23 Aug 2021 23:59:47 +0000 (09:59 +1000)]
mm/damon: implement primitives for the virtual memory address spaces
This commit introduces a reference implementation of the address space
specific low level primitives for the virtual address space, so that users
of DAMON can easily monitor the data accesses on virtual address spaces of
specific processes by simply configuring the implementation to be used by
DAMON.
The low level primitives for the fundamental access monitoring are defined
in two parts:
1. Identification of the monitoring target address range for the address
space.
2. Access check of specific address range in the target space.
The reference implementation for the virtual address space does the works
as below.
PTE Accessed-bit Based Access Check
-----------------------------------
The implementation uses PTE Accessed-bit for basic access checks. That
is, it clears the bit for the next sampling target page and checks whether
it is set again after one sampling period. This could disturb the reclaim
logic. DAMON uses ``PG_idle`` and ``PG_young`` page flags to solve the
conflict, as Idle page tracking does.
VMA-based Target Address Range Construction
-------------------------------------------
Only small parts in the super-huge virtual address space of the processes
are mapped to physical memory and accessed. Thus, tracking the unmapped
address regions is just wasteful. However, because DAMON can deal with
some level of noise using the adaptive regions adjustment mechanism,
tracking every mapping is not strictly required but could even incur a
high overhead in some cases. That said, too huge unmapped areas inside
the monitoring target should be removed to not take the time for the
adaptive mechanism.
For the reason, this implementation converts the complex mappings to three
distinct regions that cover every mapped area of the address space. Also,
the two gaps between the three regions are the two biggest unmapped areas
in the given address space. The two biggest unmapped areas would be the
gap between the heap and the uppermost mmap()-ed region, and the gap
between the lowermost mmap()-ed region and the stack in most of the cases.
Because these gaps are exceptionally huge in usual address spaces,
excluding these will be sufficient to make a reasonable trade-off. Below
shows this in detail::
<heap>
<BIG UNMAPPED REGION 1>
<uppermost mmap()-ed region>
(small mmap()-ed regions and munmap()-ed regions)
<lowermost mmap()-ed region>
<BIG UNMAPPED REGION 2>
<stack>
Link: https://lkml.kernel.org/r/20210716081449.22187-6-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Leonard Foerster <foersleo@amazon.de> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
SeongJae Park [Mon, 23 Aug 2021 23:59:46 +0000 (09:59 +1000)]
mm/damon/Kconfig: Hide PAGE_IDLE_FLAG from users
Commit 2a058a1a9914 ("mm/idle_page_tracking: make PG_idle reusable") of
linux-mm[1] makes CONFIG_PAGE_IDLE_FLAG option to be presented to the
user. However, the option is hard to be understood by users. Also, it is
not intended to be set by users but other kernel subsystems like DAMON or
IDLE_PAGE_TRACKING. To avoid confusions, this commit removes the prompt
so that the option is not presented to the user.
SeongJae Park [Mon, 23 Aug 2021 23:59:46 +0000 (09:59 +1000)]
mm/PAGE_IDLE_FLAG: Set PAGE_EXTENSION for none-64BIT
Commit 128fd80c4c07 ("mm/idle_page_tracking: Make PG_idle reusable") of
linux-mm[1] allows PAGE_IDLE_FLAG to be set without PAGE_EXTENSION while
64BIT is not set. This makes 'enum page_ext_flags' undefined, so build
fails as below for the config (!64BIT, !PAGE_EXTENSION, and
IDLE_PAGE_FLAG).
$ make ARCH=i386 allnoconfig
$ echo 'CONFIG_PAGE_IDLE_FLAG=y' >> .config
$ make olddefconfig
$ make ARCH=i386
[...]
../include/linux/page_idle.h: In function `folio_test_young':
../include/linux/page_idle.h:25:18: error: `PAGE_EXT_YOUNG' undeclared (first use in this function); did you mean `PAGEOUTRUN'?
return test_bit(PAGE_EXT_YOUNG, &page_ext->flags);
[...]
This commit fixes this issue by making PAGE_EXTENSION to be set when 64BIT
is not set and PAGE_IDLE_FLAG is set.
Link: https://lkml.kernel.org/r/20210806095153.6444-1-sj38.park@gmail.com Fixes: 128fd80c4c07 ("mm/idle_page_tracking: Make PG_idle reusable") Signed-off-by: SeongJae Park <sjpark@amazon.de> Reported-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
SeongJae Park [Mon, 23 Aug 2021 23:59:46 +0000 (09:59 +1000)]
mm/idle_page_tracking: make PG_idle reusable
PG_idle and PG_young allow the two PTE Accessed bit users, Idle Page
Tracking and the reclaim logic concurrently work while not interfering
with each other. That is, when they need to clear the Accessed bit, they
set PG_young to represent the previous state of the bit, respectively.
And when they need to read the bit, if the bit is cleared, they further
read the PG_young to know whether the other has cleared the bit meanwhile
or not.
For yet another user of the PTE Accessed bit, we could add another page
flag, or extend the mechanism to use the flags. For the DAMON usecase,
however, we don't need to do that just yet. IDLE_PAGE_TRACKING and DAMON
are mutually exclusive, so there's only ever going to be one user of the
current set of flags.
In this commit, we split out the CONFIG options to allow for the use of
PG_young and PG_idle outside of idle page tracking.
In the next commit, DAMON's reference implementation of the virtual memory
address space monitoring primitives will use it.
Link: https://lkml.kernel.org/r/20210716081449.22187-5-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Leonard Foerster <foersleo@amazon.de> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
SeongJae Park [Mon, 23 Aug 2021 23:59:46 +0000 (09:59 +1000)]
mm/damon: adaptively adjust regions
Even somehow the initial monitoring target regions are well constructed to
fulfill the assumption (pages in same region have similar access
frequencies), the data access pattern can be dynamically changed. This
will result in low monitoring quality. To keep the assumption as much as
possible, DAMON adaptively merges and splits each region based on their
access frequency.
For each ``aggregation interval``, it compares the access frequencies of
adjacent regions and merges those if the frequency difference is small.
Then, after it reports and clears the aggregated access frequency of each
region, it splits each region into two or three regions if the total
number of regions will not exceed the user-specified maximum number of
regions after the split.
In this way, DAMON provides its best-effort quality and minimal overhead
while keeping the upper-bound overhead that users set.
Link: https://lkml.kernel.org/r/20210716081449.22187-4-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Leonard Foerster <foersleo@amazon.de> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
SeongJae Park [Mon, 23 Aug 2021 23:59:46 +0000 (09:59 +1000)]
mm/damon/core: implement region-based sampling
To avoid the unbounded increase of the overhead, DAMON groups adjacent
pages that are assumed to have the same access frequencies into a
region. As long as the assumption (pages in a region have the same
access frequencies) is kept, only one page in the region is required to
be checked. Thus, for each ``sampling interval``,
1. the 'prepare_access_checks' primitive picks one page in each region,
2. waits for one ``sampling interval``,
3. checks whether the page is accessed meanwhile, and
4. increases the access count of the region if so.
Therefore, the monitoring overhead is controllable by adjusting the
number of regions. DAMON allows both the underlying primitives and user
callbacks to adjust regions for the trade-off. In other words, this
commit makes DAMON to use not only time-based sampling but also
space-based sampling.
This scheme, however, cannot preserve the quality of the output if the
assumption is not guaranteed. Next commit will address this problem.
Link: https://lkml.kernel.org/r/20210716081449.22187-3-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Leonard Foerster <foersleo@amazon.de> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
SeongJae Park [Mon, 23 Aug 2021 23:59:45 +0000 (09:59 +1000)]
mm: introduce Data Access MONitor (DAMON)
Patch series "Introduce Data Access MONitor (DAMON)", v34.
Introduction
============
DAMON is a data access monitoring framework for the Linux kernel. The
core mechanisms of DAMON called 'region based sampling' and 'adaptive
regions adjustment' (refer to 'mechanisms.rst' in the 11th patch of this
patchset for the detail) make it
- accurate (The monitored information is useful for DRAM level memory
management. It might not appropriate for Cache-level accuracy,
though.),
- light-weight (The monitoring overhead is low enough to be applied
online while making no impact on the performance of the target
workloads.), and
- scalable (the upper-bound of the instrumentation overhead is
controllable regardless of the size of target workloads.).
Using this framework, therefore, several memory management mechanisms such
as reclamation and THP can be optimized to aware real data access
patterns. Experimental access pattern aware memory management
optimization works that incurring high instrumentation overhead will be
able to have another try.
Though DAMON is for kernel subsystems, it can be easily exposed to the
user space by writing a DAMON-wrapper kernel subsystem. Then, user space
users who have some special workloads will be able to write personalized
tools or applications for deeper understanding and specialized
optimizations of their systems.
DAMON is also merged in two public Amazon Linux kernel trees that based on
v5.4.y[1] and v5.10.y[2].
The userspace tool[1] is available, released under GPLv2, and actively
being maintained. I am also planning to implement another basic user
interface in perf[2]. Also, the basic test suite for DAMON is available
under GPLv2[3].
DAMON is a part of a project called Data Access-aware Operating System
(DAOS). As the name implies, I want to improve the performance and
efficiency of systems using fine-grained data access patterns. The
optimizations are for both kernel and user spaces. I will therefore
modify or create kernel subsystems, export some of those to user space and
implement user space library / tools. Below shows the layers and
components for the project.
Raw Interface: debugfs, (sysfs), (damonfs), tracepoints, (sys_damon), ...
vvvvvvvvvvvvvvvvvvvvvvv USER SPACE vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Library: (libdamon), ...
Tools: DAMO, (perf), ...
---------------------------------------------------------------------------
The components in parentheses or marked as '...' are not implemented yet
but in the future plan. IOW, those are the TODO tasks of DAOS project.
For more detail, please refer to the plans:
https://lore.kernel.org/linux-mm/20201202082731.24828-1-sjpark@amazon.com/
Evaluations
===========
We evaluated DAMON's overhead, monitoring quality and usefulness using 24
realistic workloads on my QEMU/KVM based virtual machine running a kernel
that v24 DAMON patchset is applied.
DAMON is lightweight. It increases system memory usage by 0.39% and slows
target workloads down by 1.16%.
DAMON is accurate and useful for memory management optimizations. An
experimental DAMON-based operation scheme for THP, namely 'ethp', removes
76.15% of THP memory overheads while preserving 51.25% of THP speedup.
Another experimental DAMON-based 'proactive reclamation' implementation,
'prcl', reduces 93.38% of residential sets and 23.63% of system memory
footprint while incurring only 1.22% runtime overhead in the best case
(parsec3/freqmine).
NOTE that the experimental THP optimization and proactive reclamation are
not for production but only for proof of concepts.
Please refer to the official document[1] or "Documentation/admin-guide/mm:
Add a document for DAMON" patch in this patchset for detailed evaluation
setup and results.
In summary, DAMON has used on production systems and proved its usefulness.
DAMON as a profiler
-------------------
We analyzed characteristics of a large scale production systems of our
customers using DAMON. The systems utilize 70GB DRAM and 36 CPUs. From
this, we were able to find interesting things below.
There were obviously different access pattern under idle workload and
active workload. Under the idle workload, it accessed large memory
regions with low frequency, while the active workload accessed small
memory regions with high freuqnecy.
DAMON found a 7GB memory region that showing obviously high access
frequency under the active workload. We believe this is the
performance-effective working set and need to be protected.
There was a 4KB memory region that showing highest access frequency under
not only active but also idle workloads. We think this must be a hottest
code section like thing that should never be paged out.
For this analysis, DAMON used only 0.3-1% of single CPU time. Because we
used recording-based analysis, it consumed about 3-12 MB of disk space per
20 minutes. This is only small amount of disk space, but we can further
reduce the disk usage by using non-recording-based DAMON features. I'd
like to argue that only DAMON can do such detailed analysis (finding 4KB
highest region in 70GB memory) with the light overhead.
DAMON as a system optimization tool
-----------------------------------
We also found below potential performance problems on the systems and made
DAMON-based solutions.
The system doesn't want to make the workload suffer from the page
reclamation and thus it utilizes enough DRAM but no swap device. However,
we found the system is actively reclaiming file-backed pages, because the
system has intensive file IO. The file IO turned out to be not
performance critical for the workload, but the customer wanted to ensure
performance critical file-backed pages like code section to not mistakenly
be evicted.
Using direct IO should or `mlock()` would be a straightforward solution,
but modifying the user space code is not easy for the customer.
Alternatively, we could use DAMON-based operation scheme[1]. By using it,
we can ask DAMON to track access frequency of each region and make
'process_madvise(MADV_WILLNEED)[2]' call for regions having specific size
and access frequency for a time interval.
We also found the system is having high number of TLB misses. We tried
'always' THP enabled policy and it greatly reduced TLB misses, but the
page reclamation also been more frequent due to the THP internal
fragmentation caused memory bloat. We could try another DAMON-based
operation scheme that applies 'MADV_HUGEPAGE' to memory regions having
>=2MB size and high access frequency, while applying 'MADV_NOHUGEPAGE' to
regions having <2MB size and low access frequency.
We do not own the systems so we only reported the analysis results and
possible optimization solutions to the customers. The customers satisfied
about the analysis results and promised to try the optimization guides.
Comparison with Idle Page Tracking
==================================
Idle Page Tracking allows users to set and read idleness of pages using a
bitmap file which represents each page with each bit of the file. One
recommended usage of it is working set size detection. Users can do that
by
1. find PFN of each page for workloads in interest,
2. set all the pages as idle by doing writes to the bitmap file,
3. wait until the workload accesses its working set, and
4. read the idleness of the pages again and count pages became not idle.
NOTE: While Idle Page Tracking is for user space users, DAMON is primarily
designed for kernel subsystems though it can easily exposed to the user
space. Hence, this section only assumes such user space use of DAMON.
For what use cases Idle Page Tracking would be better?
------------------------------------------------------
1. Flexible usecases other than hotness monitoring.
Because Idle Page Tracking allows users to control the primitive (Page
idleness) by themselves, Idle Page Tracking users can do anything they
want. Meanwhile, DAMON is primarily designed to monitor the hotness of
each memory region. For this, DAMON asks users to provide sampling
interval and aggregation interval. For the reason, there could be some
use case that using Idle Page Tracking is simpler.
2. Physical memory monitoring.
Idle Page Tracking receives PFN range as input, so natively supports
physical memory monitoring.
DAMON is designed to be extensible for multiple address spaces and use
cases by implementing and using primitives for the given use case.
Therefore, by theory, DAMON has no limitation in the type of target
address space as long as primitives for the given address space exists.
However, the default primitives introduced by this patchset supports only
virtual address spaces.
Therefore, for physical memory monitoring, you should implement your own
primitives and use it, or simply use Idle Page Tracking.
Nonetheless, RFC patchsets[1] for the physical memory address space
primitives is already available. It also supports user memory same to
Idle Page Tracking.
For what use cases DAMON is better?
-----------------------------------
1. Hotness Monitoring.
Idle Page Tracking let users know only if a page frame is accessed or not.
For hotness check, the user should write more code and use more memory.
DAMON do that by itself.
2. Low Monitoring Overhead
DAMON receives user's monitoring request with one step and then provide
the results. So, roughly speaking, DAMON require only O(1) user/kernel
context switches.
In case of Idle Page Tracking, however, because the interface receives
contiguous page frames, the number of user/kernel context switches
increases as the monitoring target becomes complex and huge. As a result,
the context switch overhead could be not negligible.
Moreover, DAMON is born to handle with the monitoring overhead. Because
the core mechanism is pure logical, Idle Page Tracking users might be able
to implement the mechanism on their own, but it would be time consuming
and the user/kernel context switching will still more frequent than that
of DAMON. Also, the kernel subsystems cannot use the logic in this case.
3. Page granularity working set size detection.
Until v22 of this patchset, this was categorized as the thing Idle Page
Tracking could do better, because DAMON basically maintains additional
metadata for each of the monitoring target regions. So, in the page
granularity working set size detection use case, DAMON would incur (number
of monitoring target pages * size of metadata) memory overhead. Size of
the single metadata item is about 54 bytes, so assuming 4KB pages, about
1.3% of monitoring target pages will be additionally used.
All essential metadata for Idle Page Tracking are embedded in 'struct
page' and page table entries. Therefore, in this use case, only one
counter variable for working set size accounting is required if Idle Page
Tracking is used.
There are more details to consider, but roughly speaking, this is true in
most cases.
However, the situation changed from v23. Now DAMON supports arbitrary
types of monitoring targets, which don't use the metadata. Using that,
DAMON can do the working set size detection with no additional space
overhead but less user-kernel context switch. A first draft for the
implementation of monitoring primitives for this usage is available in a
DAMON development tree[1]. An RFC patchset for it based on this patchset
will also be available soon.
Since v24, the arbitrary type support is dropped from this patchset
because this patchset doesn't introduce real use of the type. You can
still get it from the DAMON development tree[2], though.
While Idle Page Tracking has tight coupling with base primitives (PG_Idle
and page table Accessed bits), DAMON is designed to be extensible for many
use cases and address spaces. If you need some special address type or
want to use special h/w access check primitives, you can write your own
primitives for that and configure DAMON to use those. Therefore, if your
use case could be changed a lot in future, using DAMON could be better.
Can I use both Idle Page Tracking and DAMON?
--------------------------------------------
Yes, though using them concurrently for overlapping memory regions could
result in interference to each other. Nevertheless, such use case would
be rare or makes no sense at all. Even in the case, the noise would bot
be really significant. So, you can choose whatever you want depending on
the characteristics of your use cases.
More Information
================
We prepared a showcase web site[1] that you can get more information.
There are
- the official documentations[2],
- the heatmap format dynamic access pattern of various realistic workloads for
heap area[3], mmap()-ed area[4], and stack[5] area,
- the dynamic working set size distribution[6] and chronological working set
size changes[7], and
- the latest performance test results[8].
Baseline and Complete Git Trees
===============================
The patches are based on the latest -mm tree, specifically
v5.14-rc1-mmots-2021-07-15-18-47 of https://github.com/hnaz/linux-mm. You can
also clone the complete git tree:
The web is also available:
https://github.com/sjp38/linux/releases/tag/damon/patches/v34
Development Trees
-----------------
There are a couple of trees for entire DAMON patchset series and features
for future release.
- For latest release: https://github.com/sjp38/linux/tree/damon/master
- For next release: https://github.com/sjp38/linux/tree/damon/next
Long-term Support Trees
-----------------------
For people who want to test DAMON but using LTS kernels, there are another
couple of trees based on two latest LTS kernels respectively and
containing the 'damon/master' backports.
- For v5.4.y: https://github.com/sjp38/linux/tree/damon/for-v5.4.y
- For v5.10.y: https://github.com/sjp38/linux/tree/damon/for-v5.10.y
Amazon Linux Kernel Trees
-------------------------
DAMON is also merged in two public Amazon Linux kernel trees that based on
v5.4.y[1] and v5.10.y[2].
Git Tree for Diff of Patches
============================
For easy review of diff between different versions of each patch, I
prepared a git tree containing all versions of the DAMON patchset series:
https://github.com/sjp38/damon-patches
You can clone it and use 'diff' for easy review of changes between
different versions of the patchset. For example:
First three patches implement the core logics of DAMON. The 1st patch
introduces basic sampling based hotness monitoring for arbitrary types of
targets. Following two patches implement the core mechanisms for control
of overhead and accuracy, namely regions based sampling (patch 2) and
adaptive regions adjustment (patch 3).
Now the essential parts of DAMON is complete, but it cannot work unless
someone provides monitoring primitives for a specific use case. The
following two patches make it just work for virtual address spaces
monitoring. The 4th patch makes 'PG_idle' can be used by DAMON and the
5th patch implements the virtual memory address space specific monitoring
primitives using page table Accessed bits and the 'PG_idle' page flag.
Now DAMON just works for virtual address space monitoring via the kernel
space api. To let the user space users can use DAMON, following four
patches add interfaces for them. The 6th patch adds a tracepoint for
monitoring results. The 7th patch implements a DAMON application kernel
module, namely damon-dbgfs, that simply wraps DAMON and exposes DAMON
interface to the user space via the debugfs interface. The 8th patch
further exports pid of monitoring thread (kdamond) to user space for
easier cpu usage accounting, and the 9th patch makes the debugfs interface
to support multiple contexts.
Three patches for maintainability follows. The 10th patch adds
documentations for both the user space and the kernel space. The 11th
patch provides unit tests (based on the kunit) while the 12th patch adds
user space tests (based on the kselftest).
Finally, the last patch (13th) updates the MAINTAINERS file.
This patch (of 13):
DAMON is a data access monitoring framework for the Linux kernel. The
core mechanisms of DAMON make it
- accurate (the monitoring output is useful enough for DRAM level
performance-centric memory management; It might be inappropriate for
CPU cache levels, though),
- light-weight (the monitoring overhead is normally low enough to be
applied online), and
- scalable (the upper-bound of the overhead is in constant range
regardless of the size of target workloads).
Using this framework, hence, we can easily write efficient kernel space
data access monitoring applications. For example, the kernel's memory
management mechanisms can make advanced decisions using this.
Experimental data access aware optimization works that incurring high
access monitoring overhead could again be implemented on top of this.
Due to its simple and flexible interface, providing user space interface
would be also easy. Then, user space users who have some special
workloads can write personalized applications for better understanding and
optimizations of their workloads and systems.
===
Nevertheless, this commit is defining and implementing only basic access
check part without the overhead-accuracy handling core logic. The basic
access check is as below.
The output of DAMON says what memory regions are how frequently accessed
for a given duration. The resolution of the access frequency is
controlled by setting ``sampling interval`` and ``aggregation interval``.
In detail, DAMON checks access to each page per ``sampling interval`` and
aggregates the results. In other words, counts the number of the accesses
to each region. After each ``aggregation interval`` passes, DAMON calls
callback functions that previously registered by users so that users can
read the aggregated results and then clears the results. This can be
described in below simple pseudo-code::
init()
while monitoring_on:
for page in monitoring_target:
if accessed(page):
nr_accesses[page] += 1
if time() % aggregation_interval == 0:
for callback in user_registered_callbacks:
callback(monitoring_target, nr_accesses)
for page in monitoring_target:
nr_accesses[page] = 0
if time() % update_interval == 0:
update()
sleep(sampling interval)
The target regions constructed at the beginning of the monitoring and
updated after each ``regions_update_interval``, because the target regions
could be dynamically changed (e.g., mmap() or memory hotplug). The
monitoring overhead of this mechanism will arbitrarily increase as the
size of the target workload grows.
The basic monitoring primitives for actual access check and dynamic target
regions construction aren't in the core part of DAMON. Instead, it allows
users to implement their own primitives that are optimized for their use
case and configure DAMON to use those. In other words, users cannot use
current version of DAMON without some additional works.
Following commits will implement the core mechanisms for the
overhead-accuracy control and default primitives implementations.
Link: https://lkml.kernel.org/r/20210716081449.22187-1-sj38.park@gmail.com Link: https://lkml.kernel.org/r/20210716081449.22187-2-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Leonard Foerster <foersleo@amazon.de> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: David Hildenbrand <david@redhat.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Marco Elver <elver@google.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Joe Perches <joe@perches.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: David Rientjes <rientjes@google.com> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: Markus Boehme <markubo@amazon.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Marco Elver [Mon, 23 Aug 2021 23:59:45 +0000 (09:59 +1000)]
kfence: show cpu and timestamp in alloc/free info
Record cpu and timestamp on allocations and frees, and show them in
reports. Upon an error, this can help correlate earlier messages in the
kernel log via allocation and free timestamps.
Link: https://lkml.kernel.org/r/20210714175312.2947941-1-elver@google.com Suggested-by: Joern Engel <joern@purestorage.com> Signed-off-by: Marco Elver <elver@google.com> Acked-by: Alexander Potapenko <glider@google.com> Acked-by: Joern Engel <joern@purestorage.com> Cc: Yuanyuan Zhong <yzhong@purestorage.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Jordy Zomer [Mon, 23 Aug 2021 23:59:45 +0000 (09:59 +1000)]
mm/secretmem: use refcount_t instead of atomic_t
When a secret memory region is active, memfd_secret disables hibernation.
One of the goals is to keep the secret data from being written to
persistent-storage.
It accomplishes this by maintaining a reference count to
`secretmem_users`. Once this reference is held your system can not be
hibernated due to the check in `hibernation_available()`. However,
because `secretmem_users` is of type `atomic_t`, reference counter
overflows are possible.
As you can see there's an `atomic_inc` for each `memfd` that is opened in
the `memfd_secret` syscall. If a local attacker succeeds to open 2^32
memfd's, the counter will wrap around to 0. This implies that you may
hibernate again, even though there are still regions of this secret
memory, thereby bypassing the security check.
In an attempt to fix this I have used `refcount_t` instead of `atomic_t`
which prevents reference counter overflows.
Link: https://lkml.kernel.org/r/20210820043339.2151352-1-jordy@pwning.systems Signed-off-by: Jordy Zomer <jordy@pwning.systems> Cc: Kees Cook <keescook@chromium.org>, Cc: Jordy Zomer <jordy@jordyzomer.github.io> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Mike Rapoport <rppt@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Muchun Song [Mon, 23 Aug 2021 23:59:45 +0000 (09:59 +1000)]
mm: introduce PAGEFLAGS_MASK to replace ((1UL << NR_PAGEFLAGS) - 1)
Instead of hard-coding ((1UL << NR_PAGEFLAGS) - 1) everywhere, introducing
PAGEFLAGS_MASK to make the code clear to get the page flags.
Link: https://lkml.kernel.org/r/20210819150712.59948-1-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Roman Gushchin <guro@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
projects / users / jedix / linux-maple.git / log