Patch series "background initramfs unpacking, and CONFIG_MODPROBE_PATH", v3.
These two patches are independent, but better-together.
The second is a rather trivial patch that simply allows the developer to
change "/sbin/modprobe" to something else - e.g. the empty string, so
that all request_module() during early boot return -ENOENT early, without
even spawning a usermode helper, needlessly synchronizing with the
initramfs unpacking.
The first patch delegates decompressing the initramfs to a worker thread,
allowing do_initcalls() in main.c to proceed to the device_ and late_
initcalls without waiting for that decompression (and populating of
rootfs) to finish. Obviously, some of those later calls may rely on the
initramfs being available, so I've added synchronization points in the
firmware loader and usermodehelper paths - there might be other places
that would need this, but so far no one has been able to think of any
places I have missed.
There's not much to win if most of the functionality needed during boot is
only available as modules. But systems with a custom-made .config and
initramfs can boot faster, partly due to utilizing more than one cpu
earlier, partly by avoiding known-futile modprobe calls (which would still
trigger synchronization with the initramfs unpacking, thus eliminating
most of the first benefit).
This patch (of 2):
Most of the boot process doesn't actually need anything from the
initramfs, until of course PID1 is to be executed. So instead of doing
the decompressing and populating of the initramfs synchronously in
populate_rootfs() itself, push that off to a worker thread.
This is primarily motivated by an embedded ppc target, where unpacking
even the rather modest sized initramfs takes 0.6 seconds, which is long
enough that the external watchdog becomes unhappy that it doesn't get
attention soon enough. By doing the initramfs decompression in a worker
thread, we get to do the device_initcalls and hence start petting the
watchdog much sooner.
Normal desktops might benefit as well. On my mostly stock Ubuntu kernel,
my initramfs is a 26M xz-compressed blob, decompressing to around 126M.
That takes almost two seconds:
[ 0.201454] Trying to unpack rootfs image as initramfs...
[ 1.976633] Freeing initrd memory: 29416K
Before this patch, these lines occur consecutively in dmesg. With this
patch, the timestamps on these two lines is roughly the same as above, but
with 172 lines inbetween - so more than one cpu has been kept busy doing
work that would otherwise only happen after the populate_rootfs()
finished.
Should one of the initcalls done after rootfs_initcall time (i.e., device_
and late_ initcalls) need something from the initramfs (say, a kernel
module or a firmware blob), it will simply wait for the initramfs
unpacking to be done before proceeding, which should in theory make this
completely safe.
But if some driver pokes around in the filesystem directly and not via one
of the official kernel interfaces (i.e. request_firmware*(),
call_usermodehelper*) that theory may not hold - also, I certainly might
have missed a spot when sprinkling wait_for_initramfs(). So there is an
escape hatch in the form of an initramfs_async= command line parameter.
Link: https://lkml.kernel.org/r/20210313212528.2956377-1-linux@rasmusvillemoes.dk Link: https://lkml.kernel.org/r/20210313212528.2956377-2-linux@rasmusvillemoes.dk Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Cc: Jessica Yu <jeyu@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Takashi Iwai <tiwai@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
It's currently nigh impossible to get these pr_debug()s to print
something. Being guarded by initcall_debug means one has to enable tons
of other debug output during boot, and the system_state condition further
means it's impossible to get them when loading modules later.
Also, the compiler can't know that these global conditions do not change,
so there are W=2 warnings
kernel/async.c:125:9: warning: `calltime' may be used uninitialized in this function [-Wmaybe-uninitialized]
kernel/async.c:300:9: warning: `starttime' may be used uninitialized in this function [-Wmaybe-uninitialized]
Make it possible, for a DYNAMIC_DEBUG kernel, to get these to print their
messages by booting with appropriate 'dyndbg="file async.c +p"' command
line argument. For a non-DYNAMIC_DEBUG kernel, pr_debug() compiles to
nothing.
This does cost doing an unconditional ktime_get() for the starttime value,
but the corresponding ktime_get for the end time can be elided by
factoring it into a function which only gets called if the printk()
arguments end up being evaluated.
'assert.h' included in 'sparsebit.c' is duplicated.
It is also included in the 161th line.
'string.h' included in 'mincore_selftest.c' is duplicated.
It is also included in the 15th line.
'sched.h' included in 'tlbie_test.c' is duplicated.
It is also included in the 33th line.
Link: https://lkml.kernel.org/r/20210316073336.426255-1-zhang.yunkai@zte.com.cn Signed-off-by: Zhang Yunkai <zhang.yunkai@zte.com.cn> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
All functions that search for IORESOURCE_SYSTEM_RAM or IORESOURCE_MEM
resources now properly consider the whole resource tree, not just the
first level. Let's drop the unused first_lvl / siblings_only logic.
Remove documentation that indicates that some functions behave differently,
all consider the full resource tree now.
Link: https://lkml.kernel.org/r/20210325115326.7826-4-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Cc: Dave Young <dyoung@redhat.com> Cc: Baoquan He <bhe@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Keith Busch <keith.busch@intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Qian Cai <cai@lca.pw> Cc: Oscar Salvador <osalvador@suse.de> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
David Hildenbrand [Tue, 13 Apr 2021 22:21:28 +0000 (08:21 +1000)]
kernel/resource: make walk_mem_res() find all busy IORESOURCE_MEM resources
It used to be true that we can have system RAM (IORESOURCE_SYSTEM_RAM |
IORESOURCE_BUSY) only on the first level in the resource tree. However,
this is no longer holds for driver-managed system RAM (i.e., added via
dax/kmem and virtio-mem), which gets added on lower levels, for example,
inside device containers.
IORESOURCE_SYSTEM_RAM is defined as IORESOURCE_MEM | IORESOURCE_SYSRAM and
just a special type of IORESOURCE_MEM.
The function walk_mem_res() only considers the first level and is used in
arch/x86/mm/ioremap.c:__ioremap_check_mem() only. We currently fail to
identify System RAM added by dax/kmem and virtio-mem as
"IORES_MAP_SYSTEM_RAM", for example, allowing for remapping of such
"normal RAM" in __ioremap_caller().
Let's find all IORESOURCE_MEM | IORESOURCE_BUSY resources, making the
function behave similar to walk_system_ram_res().
Link: https://lkml.kernel.org/r/20210325115326.7826-3-david@redhat.com Fixes: ebf71552bb0e ("virtio-mem: Add parent resource for all added "System RAM"") Fixes: c221c0b0308f ("device-dax: "Hotplug" persistent memory for use like normal RAM") Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Cc: Dave Young <dyoung@redhat.com> Cc: Baoquan He <bhe@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Keith Busch <keith.busch@intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Qian Cai <cai@lca.pw> Cc: Oscar Salvador <osalvador@suse.de> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
David Hildenbrand [Tue, 13 Apr 2021 22:21:28 +0000 (08:21 +1000)]
kernel/resource: make walk_system_ram_res() find all busy IORESOURCE_SYSTEM_RAM resources
Patch series "kernel/resource: make walk_system_ram_res() and walk_mem_res() search the whole tree", v2.
Playing with kdump+virtio-mem I noticed that kexec_file_load() does not
consider System RAM added via dax/kmem and virtio-mem when preparing the
elf header for kdump. Looking into the details, the logic used in
walk_system_ram_res() and walk_mem_res() seems to be outdated.
walk_system_ram_range() already does the right thing, let's change
walk_system_ram_res() and walk_mem_res(), and clean up.
Loading a kdump kernel via "kexec -p -s" ... will result in the kdump
kernel to also dump dax/kmem and virtio-mem added System RAM now.
Note: kexec-tools on x86-64 also have to be updated to consider this
memory in the kexec_load() case when processing /proc/iomem.
This patch (of 3):
It used to be true that we can have system RAM (IORESOURCE_SYSTEM_RAM |
IORESOURCE_BUSY) only on the first level in the resource tree. However,
this is no longer holds for driver-managed system RAM (i.e., added via
dax/kmem and virtio-mem), which gets added on lower levels, for example,
inside device containers.
We have two users of walk_system_ram_res(), which currently only
consideres the first level:
a) kernel/kexec_file.c:kexec_walk_resources() -- We properly skip
IORESOURCE_SYSRAM_DRIVER_MANAGED resources via
locate_mem_hole_callback(), so even after this change, we won't be
placing kexec images onto dax/kmem and virtio-mem added memory. No
change.
b) arch/x86/kernel/crash.c:fill_up_crash_elf_data() -- we're currently
not adding relevant ranges to the crash elf header, resulting in them
not getting dumped via kdump.
This change fixes loading a crashkernel via kexec_file_load() and
including dax/kmem and virtio-mem added System RAM in the crashdump on
x86-64. Note that e.g,, arm64 relies on memblock data and, therefore,
always considers all added System RAM already.
Let's find all IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY resources, making
the function behave like walk_system_ram_range().
Link: https://lkml.kernel.org/r/20210325115326.7826-1-david@redhat.com Link: https://lkml.kernel.org/r/20210325115326.7826-2-david@redhat.com Fixes: ebf71552bb0e ("virtio-mem: Add parent resource for all added "System RAM"") Fixes: c221c0b0308f ("device-dax: "Hotplug" persistent memory for use like normal RAM") Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Acked-by: Baoquan He <bhe@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Cc: Dave Young <dyoung@redhat.com> Cc: Baoquan He <bhe@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Keith Busch <keith.busch@intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Qian Cai <cai@lca.pw> Cc: Oscar Salvador <osalvador@suse.de> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Barry Song [Tue, 13 Apr 2021 22:21:28 +0000 (08:21 +1000)]
scripts/gdb: add lx_current support for arm64
arm64 uses SP_EL0 to save the current task_struct address. While running
in EL0, SP_EL0 is clobbered by userspace. So if the upper bit is not 1
(not TTBR1), the current address is invalid. This patch checks the upper
bit of SP_EL0, if the upper bit is 1, lx_current() of arm64 will return
the derefrence of current task. Otherwise, lx_current() will tell users
they are running in userspace(EL0).
While arm64 is running in EL0, it is actually pointless to print current
task as the memory of kernel space is not accessible in EL0.
Link: https://lkml.kernel.org/r/20210314203444.15188-3-song.bao.hua@hisilicon.com Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Cc: Jan Kiszka <jan.kiszka@siemens.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kieran Bingham <kbingham@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Barry Song [Tue, 13 Apr 2021 22:21:28 +0000 (08:21 +1000)]
scripts/gdb: document lx_current is only supported by x86
Patch series "scripts/gdb: clarify the platforms supporting lx_current and add arm64 support", v2.
lx_current depends on per_cpu current_task variable which exists on x86
only. so it actually works on x86 only. the 1st patch documents this
clearly; the 2nd patch adds support for arm64.
This patch (of 2):
x86 is the only architecture which has per_cpu current_task:
arch$ git grep current_task | grep -i per_cpu
x86/include/asm/current.h:DECLARE_PER_CPU(struct task_struct *, current_task);
x86/kernel/cpu/common.c:DEFINE_PER_CPU(struct task_struct *, current_task) ____cacheline_aligned =
x86/kernel/cpu/common.c:EXPORT_PER_CPU_SYMBOL(current_task);
x86/kernel/cpu/common.c:DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
x86/kernel/cpu/common.c:EXPORT_PER_CPU_SYMBOL(current_task);
x86/kernel/smpboot.c: per_cpu(current_task, cpu) = idle;
On other architectures, lx_current() will lead to a python exception:
(gdb) p $lx_current().pid
Python Exception <class 'gdb.error'> No symbol "current_task" in current context.:
Error occurred in Python: No symbol "current_task" in current context.
To avoid more people struggling and wasting time in other architectures,
document it.
Johannes Berg [Tue, 13 Apr 2021 22:21:27 +0000 (08:21 +1000)]
gdb: lx-symbols: store the abspath()
If we store the relative path, the user might later cd to a different
directory, and that would break the automatic symbol resolving that
happens when a module is loaded into the target kernel. Fix this by
storing the abspath() of each path given, just like we already do for the
cwd (os.getcwd() is absolute.)
Change wait_event_hrtimeout() to not call __wait_event_hrtimeout() if
timeout == 0, this matches other _timeout() helpers in wait.h.
This allows to simplify its only user, read_events(), it no longer needs
to optimize the "until == 0" case by hand.
Note: this patch doesn't use ___wait_cond_timeout because _hrtimeout()
also differs in that it returns 0 if succeeds and -ETIME on timeout.
Perhaps we should change this to make it fully compatible with other
helpers.
Link: http://lkml.kernel.org/r/20190607175413.GA29187@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: David Laight <David.Laight@ACULAB.COM> Cc: Deepa Dinamani <deepa.kernel@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Eric Wong <e@80x24.org> Cc: Peter Zijlstra <peterz@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>
He Ying [Tue, 13 Apr 2021 22:21:27 +0000 (08:21 +1000)]
smp: kernel/panic.c - silence warnings
We found these warnings in kernel/panic.c by using sparse tool:
warning: symbol 'panic_smp_self_stop' was not declared.
warning: symbol 'nmi_panic_self_stop' was not declared.
warning: symbol 'crash_smp_send_stop' was not declared.
To avoid them, add declarations for these three functions in
include/linux/smp.h.
Link: https://lkml.kernel.org/r/20210316084150.75201-1-heying24@huawei.com Signed-off-by: He Ying <heying24@huawei.com> Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Johannes Berg [Tue, 13 Apr 2021 22:21:26 +0000 (08:21 +1000)]
gcov: use kvmalloc()
Using vmalloc() in gcov is really quite wasteful, many of the objects
allocated are really small (e.g. I've seen 24 bytes.) Use kvmalloc() to
automatically pick the better of kmalloc() or vmalloc() depending on the
size.
Johannes Berg [Tue, 13 Apr 2021 22:21:26 +0000 (08:21 +1000)]
gcov: combine common code
There's a lot of duplicated code between gcc and clang implementations,
move it over to fs.c to simplify the code, there's no reason to believe
that for small data like this one would not just implement the simple
convert_to_gcda() function.
Pavel Tatashin [Tue, 13 Apr 2021 22:21:25 +0000 (08:21 +1000)]
kexec: dump kmessage before machine_kexec
kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before
machine_restart(), machine_halt(), machine_power_off(), the only one that
is missing is machine_kexec().
The dmesg output that it contains can be used to study the shutdown
performance of both kernel and systemd during kexec reboot.
Here is example of dmesg data collected after kexec:
Jia-Ju Bai [Tue, 13 Apr 2021 22:21:25 +0000 (08:21 +1000)]
kernel: kexec_file: fix error return code of kexec_calculate_store_digests()
When vzalloc() returns NULL to sha_regions, no error return code of
kexec_calculate_store_digests() is assigned. To fix this bug, ret is
assigned with -ENOMEM in this case.
Link: https://lkml.kernel.org/r/20210309083904.24321-1-baijiaju1990@gmail.com Fixes: a43cac0d9dc2 ("kexec: split kexec_file syscall code to kexec_file.c") Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> Reported-by: TOTE Robot <oslab@tsinghua.edu.cn> Acked-by: Baoquan He <bhe@redhat.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/20210304124626.13927-1-pmenzel@molgen.mpg.de Signed-off-by: Joe LeVeque <jolevequ@microsoft.com> Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de> Acked-by: Baoquan He <bhe@redhat.com> Cc: Guohan Lu <lguohan@gmail.com> Cc: Joe LeVeque <jolevequ@microsoft.com> Cc: Paul Menzel <pmenzel@molgen.mpg.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
kernel/crash_core: add crashkernel=auto for vmcore creation
This adds crashkernel=auto feature to configure reserved memory for vmcore
creation. CONFIG_CRASH_AUTO_STR is defined to be set for different kernel
distributions and different archs based on their needs.
Link: https://lkml.kernel.org/r/20210223174153.72802-1-saeed.mirzamohammadi@oracle.com Signed-off-by: Saeed Mirzamohammadi <saeed.mirzamohammadi@oracle.com> Signed-off-by: John Donnelly <john.p.donnelly@oracle.com> Tested-by: John Donnelly <john.p.donnelly@oracle.com>
ed-by: Dave Young <dyoung@redhat.com> Cc: Baoquan He <bhe@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Guilherme G. Piccoli" <gpiccoli@canonical.com> Cc: Kees Cook <keescook@chromium.org> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org> Cc: YiFei Zhu <yifeifz2@illinois.edu> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Stephen Boyd <sboyd@kernel.org> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Colin Ian King <colin.king@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Jim Newsome [Tue, 13 Apr 2021 22:21:24 +0000 (08:21 +1000)]
do_wait: make PIDTYPE_PID case O(1) instead of O(n)
Add a special-case when waiting on a pid (via waitpid, waitid, wait4, etc)
to avoid doing an O(n) scan of children and tracees, and instead do an
O(1) lookup. This improves performance when waiting on a pid from a
thread group with many children and/or tracees.
Time to fork and then call waitpid on the child, from a task that already
has N children [1]:
N | Before | After
-----|---------|------
1 | 74 us | 74 us
20 | 72 us | 75 us
100 | 83 us | 77 us
500 | 99 us | 74 us
1000 | 179 us | 75 us
5000 | 804 us | 79 us
8000 | 1268 us | 78 us
[1]: https://lkml.org/lkml/2021/3/12/1567
This can make a substantial performance improvement for applications with
a thread that has many children or tracees and frequently needs to wait on
them. Tools that use ptrace to intercept syscalls for a large number of
processes are likely to fall into this category. In particular this patch
was developed while building a ptrace-based second generation of the
Shadow emulator [2], for which it allows us to avoid quadratic scaling
(without having to use a workaround that introduces a ~40% performance
penalty) [3]. Other examples of tools that fall into this category which
this patch may help include User Mode Linux [4] and DetTrace [5].
Gustavo A. R. Silva [Tue, 13 Apr 2021 22:21:24 +0000 (08:21 +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.
339ddb53d373 (fs/epoll: remove unnecessary wakeups of nested epoll)
changed the userspace visible behavior of exclusive waiters blocked on a
common epoll descriptor upon a single event becoming ready. Previously,
all tasks doing epoll_wait would awake, and now only one is awoken,
potentially causing missed wakeups on applications that rely on this
behavior, such as Apache Qpid.
While the aforementioned commit aims at having only a wakeup single path
in ep_poll_callback (with the exceptions of epoll_ctl cases), we need to
restore the wakeup in what was the old ep_scan_ready_list() such that the
next thread can be awoken, in a cascading style, after the waker's
corresponding ep_send_events().
Link: https://lkml.kernel.org/r/20210405231025.33829-3-dave@stgolabs.net Fixes: 339ddb53d373 ("fs/epoll: remove unnecessary wakeups of nested epoll") Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Jason Baron <jbaron@akamai.com> Cc: Roman Penyaev <rpenyaev@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Patch series "fs/epoll: restore user-visible behavior upon event ready".
This series tries to address a change in user visible behavior, reported
in https://bugzilla.kernel.org/show_bug.cgi?id=208943.
Epoll does not report an event to all the threads running epoll_wait()
on the same epoll descriptor. Unsurprisingly, this was bisected back to 339ddb53d373 (fs/epoll: remove unnecessary wakeups of nested epoll), which
has had various problems in the past, beyond only nested epoll usage.
This patch (of 2):
This incorporates the testcase originally reported in:
Which ensures an event is reported to all threads blocked on the same
epoll descriptor, otherwise only a single thread will receive the wakeup
once the event become ready.
Vincent Mailhol [Tue, 13 Apr 2021 22:21:22 +0000 (08:21 +1000)]
checkpatch: exclude four preprocessor sub-expressions from MACRO_ARG_REUSE
__must_be_array, offsetof, sizeof_field and __stringify are all
preprocessor macros and do not evaluate their arguments. As such, it is
safe not to warn when arguments are being reused in those four
sub-expressions.
Randy Dunlap [Tue, 13 Apr 2021 22:21:22 +0000 (08:21 +1000)]
lib: parser: clean up kernel-doc
Mark match_uint() as kernel-doc notation since it is already fully
annotated as such. Use % prefix on constants in kernel-doc comments.
Convert function return descriptions to use the "Return:" kernel-doc
notation.
Link: https://lkml.kernel.org/r/20210407034514.5651-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Alex Shi [Tue, 13 Apr 2021 22:21:21 +0000 (08:21 +1000)]
lib/genalloc: add parameter description to fix doc compile warning
commit 52fbf1134d47 ("lib/genalloc.c: fix allocation of aligned buffer
from non-aligned chunk") add a new parameter 'start_addr' w/o
description for it. That cause some doc compile warning:
lib/genalloc.c:649: warning: Function parameter or member 'start_addr' not described in 'gen_pool_first_fit'
lib/genalloc.c:667: warning: Function parameter or member 'start_addr' not described in 'gen_pool_first_fit_align'
lib/genalloc.c:694: warning: Function parameter or member 'start_addr' not described in 'gen_pool_fixed_alloc'
lib/genalloc.c:729: warning: Function parameter or member 'start_addr' not described in 'gen_pool_first_fit_order_align'
lib/genalloc.c:752: warning: Function parameter or member 'start_addr' not described in 'gen_pool_best_fit'
This patch fix this by adding parameter descriptions.
Link: https://lkml.kernel.org/r/20210405132021.131231-1-alexs@kernel.org Signed-off-by: Alex Shi <alexs@kernel.org> Cc: Alexey Skidanov <alexey.skidanov@intel.com> Cc: Huang Shijie <sjhuang@iluvatar.ai> Cc: Alex Shi <alexs@kernel.org> Cc: Bhaskar Chowdhury <unixbhaskar@gmail.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>
Alex Shi [Tue, 13 Apr 2021 22:21:21 +0000 (08:21 +1000)]
lib/percpu_counter: tame kernel-doc compile warning
commit 3e8f399da490 ("writeback: rework wb_[dec|inc]_stat family of
functions") add some function description of percpu_counter_add_batch.
but the double '*' in comments means a kernel-doc format comment which
isn't right.
Since the whole file of lib/percpu_counter.c has no any other kernel-doc
format comments, we'd better to remove this incomplete one to tame the
kernel-doc warning:
lib/percpu_counter.c:83: warning: Function parameter or member 'fbc' not described in 'percpu_counter_add_batch'
lib/percpu_counter.c:83: warning: Function parameter or member 'amount' not described in 'percpu_counter_add_batch'
lib/percpu_counter.c:83: warning: Function parameter or member 'batch' not described in 'percpu_counter_add_batch'
Link: https://lkml.kernel.org/r/20210405135505.132446-1-alexs@kernel.org Signed-off-by: Alex Shi <alexs@kernel.org> Cc: Nikolay Borisov <nborisov@suse.com> Cc: Stephen Boyd <swboyd@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
In RT system, the spin_lock will be replaced by sleepable rt_mutex lock,
in __call_rcu(), disable interrupts before calling
kasan_record_aux_stack(), will trigger above calltrace, replace spinlock
with raw_spinlock.
Link: https://lkml.kernel.org/r/20210329084009.27013-1-qiang.zhang@windriver.com Signed-off-by: Zqiang <qiang.zhang@windriver.com> Reported-by: Andrew Halaney <ahalaney@redhat.com> Cc: Alexander Potapenko <glider@google.com> Cc: Gustavo A. R. Silva <gustavoars@kernel.org> Cc: Vijayanand Jitta <vjitta@codeaurora.org> Cc: Vinayak Menon <vinmenon@codeaurora.org> Cc: Yogesh Lal <ylal@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Richard Fitzgerald [Tue, 13 Apr 2021 22:21:20 +0000 (08:21 +1000)]
lib: crc8: pointer to data block should be const
crc8() does not change the data passed to it, so the pointer argument
should be declared const. This avoids callers that receive const data
having to cast it to a non-const pointer to call crc8().
Link: https://lkml.kernel.org/r/20210329122409.3291-1-rf@opensource.cirrus.com Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
h8300: rearrange headers inclusion order in asm/bitops
The commit a5145bdad3ff ("arch: rearrange headers inclusion order in
asm/bitops for m68k and sh") on next-20210401 fixed header ordering issue.
h8300 has similar problem, which was overlooked by me.
h8300 includes bitmap/{find,le}.h prior to ffs/fls headers. New fast-path
implementation in find.h requires ffs/fls. Reordering the headers inclusion
sequence helps to prevent compile-time implicit function declaration error.
v2: change wording in the comment.
Link: https://lkml.kernel.org/r/20210406183625.794227-1-yury.norov@gmail.com Signed-off-by: Yury Norov <yury.norov@gmail.com> Reported-by: kernel test robot <lkp@intel.com> Reported-by: Guenter Roeck <linux@roeck-us.net> Tested-by: Guenter Roeck <linux@roeck-us.net>Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Similarly to bitmap functions, find_next_*_bit() users will benefit if
we'll handle a case of bitmaps that fit into a single word inline. In the
very best case, the compiler may replace a function call with a few
instructions.
This is the quite typical find_next_bit() user:
unsigned int cpumask_next(int n, const struct cpumask *srcp)
{
/* -1 is a legal arg here. */
if (n != -1)
cpumask_check(n);
return find_next_bit(cpumask_bits(srcp), nr_cpumask_bits, n + 1);
}
EXPORT_SYMBOL(cpumask_next);
lib/find_bit.c declares five single-line wrappers for _find_next_bit().
We may turn those wrappers to inline functions. It eliminates unneeded
function calls and opens room for compile-time optimizations.
Link: https://lkml.kernel.org/r/20210401003153.97325-8-yury.norov@gmail.com Signed-off-by: Yury Norov <yury.norov@gmail.com> Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: David Sterba <dsterba@suse.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Jianpeng Ma <jianpeng.ma@intel.com> Cc: Joe Perches <joe@perches.com> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Rich Felker <dalias@libc.org> Cc: Stefano Brivio <sbrivio@redhat.com> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Cc: Wolfram Sang <wsa+renesas@sang-engineering.com> Cc: Yoshinori Sato <ysato@users.osdn.me> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
arch: rearrange headers inclusion order in asm/bitops for m68k and sh
m68k and sh include bitmap/{find,le}.h prior to ffs/fls headers. New
fast-path implementation in find.h requires ffs/fls. Reordering the
headers inclusion sequence helps to prevent compile-time implicit function
declaration error.
Link: https://lkml.kernel.org/r/20210401003153.97325-5-yury.norov@gmail.com Signed-off-by: Yury Norov <yury.norov@gmail.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: David Sterba <dsterba@suse.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Jianpeng Ma <jianpeng.ma@intel.com> Cc: Joe Perches <joe@perches.com> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Rich Felker <dalias@libc.org> Cc: Stefano Brivio <sbrivio@redhat.com> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Cc: Wolfram Sang <wsa+renesas@sang-engineering.com> Cc: Yoshinori Sato <ysato@users.osdn.me> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Patch series "lib/find_bit: fast path for small bitmaps", v6.
Bitmap operations are much simpler and faster in case of small bitmaps
which fit into a single word. In linux/bitmap.c we have a machinery that
allows compiler to replace actual function call with a few instructions if
bitmaps passed into the function are small and their size is known at
compile time.
find_*_bit() API lacks this functionality; but users will benefit from it
a lot. One important example is cpumask subsystem when NR_CPUS <=
BITS_PER_LONG.
This patch (of 12):
GENMASK(h, l) may be passed with unsigned types. In such case,
type-limits warning is generated for example in case of GENMASK(h, 0).
Link: https://lkml.kernel.org/r/20210401003153.97325-1-yury.norov@gmail.com Link: https://lkml.kernel.org/r/20210401003153.97325-2-yury.norov@gmail.com Signed-off-by: Yury Norov <yury.norov@gmail.com> Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: David Sterba <dsterba@suse.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Jianpeng Ma <jianpeng.ma@intel.com> Cc: Joe Perches <joe@perches.com> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Rich Felker <dalias@libc.org> Cc: Stefano Brivio <sbrivio@redhat.com> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Cc: Wolfram Sang <wsa+renesas@sang-engineering.com> Cc: Yoshinori Sato <ysato@users.osdn.me> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
init_groups is declared in both cred.h and init_task.h, but it is not
actually referenced anywhere outside of cred.c where it is defined. So
make it static and remove the declarations.
Wan Jiabing [Tue, 13 Apr 2021 22:21:15 +0000 (08:21 +1000)]
linux/profile.h: remove unnecessary declaration
Declaring struct pt_regs is unnecessary. On the one hand, there is no
function using it; on the other hand, struct pt_regs has been declared in
linux/kernel.h. Remove them.
Andy Shevchenko [Tue, 13 Apr 2021 22:21:15 +0000 (08:21 +1000)]
kernel.h: drop inclusion in bitmap.h
The bitmap.h header is used in a lot of code around the kernel. Besides
that it includes kernel.h which sometimes makes a loop.
The problem here is many unneeded loops that make header hell
dependencies. For example, how may you move bitmap_zalloc() from C-file
to the header? Currently it's impossible. And bitmap.h here is only the
tip of an iceberg.
kerne.h is a dump of everything that even has nothing in common at all.
We may still have it, but in my new code I prefer to include only the
headers that I want to use, without the bulk of unneeded kernel code.
Break the loop by introducing align.h, including it in kernel.h and
bitmap.h followed by replacing kernel.h with limits.h.
Link: https://lkml.kernel.org/r/20210326170347.37441-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Yury Norov <yury.norov@gmail.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> 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>
My UEK-derived config has 1030 files depending on pagemap.h before this
change. Afterwards, just 326 files need to be rebuilt when I touch
pagemap.h. I think blkdev.h is probably included too widely, but
untangling that dependency is harder and this solves my problem. x86
allmodconfig builds, but there may be implicit include problems on other
architectures.
Link: https://lkml.kernel.org/r/20210309195747.283796-1-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by: Dan Williams <dan.j.williams@intel.com> [nvdimm] Acked-by: Jens Axboe <axboe@kernel.dk> [block] Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Coly Li <colyli@suse.de> [bcache] Acked-by: Martin K. Petersen <martin.petersen@oracle.com> [scsi] Reviewed-by: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
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>
And 'ino' field to /proc/<pid>/fdinfo/<FD> and
/proc/<pid>/task/<tid>/fdinfo/<FD>.
The inode numbers can be used to uniquely identify DMA buffers in user
space and avoids a dependency on /proc/<pid>/fd/* when accounting
per-process DMA buffer sizes.
Link: https://lkml.kernel.org/r/20210308170651.919148-2-kaleshsingh@google.com Signed-off-by: Kalesh Singh <kaleshsingh@google.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Christian König <christian.koenig@amd.com> Cc: Jann Horn <jannh@google.com> Cc: Jeff Vander Stoep <jeffv@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Hridya Valsaraju <hridya@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Kalesh Singh <kaleshsingh@google.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Alexey Gladkov <gladkov.alexey@gmail.com> Cc: Szabolcs Nagy <szabolcs.nagy@arm.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Michel Lespinasse <walken@google.com> Cc: Bernd Edlinger <bernd.edlinger@hotmail.de> Cc: Andrei Vagin <avagin@gmail.com> Cc: Helge Deller <deller@gmx.de> Cc: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
procfs: allow reading fdinfo with PTRACE_MODE_READ
Android captures per-process system memory state when certain low memory
events (e.g a foreground app kill) occur, to identify potential memory
hoggers. In order to measure how much memory a process actually consumes,
it is necessary to include the DMA buffer sizes for that process in the
memory accounting. Since the handle to DMA buffers are raw FDs, it is
important to be able to identify which processes have FD references to a
DMA buffer.
Currently, DMA buffer FDs can be accounted using /proc/<pid>/fd/* and
/proc/<pid>/fdinfo -- both are only readable by the process owner, as
follows:
1. Do a readlink on each FD.
2. If the target path begins with "/dmabuf", then the FD is a dmabuf FD.
3. stat the file to get the dmabuf inode number.
4. Read/ proc/<pid>/fdinfo/<fd>, to get the DMA buffer size.
Accessing other processes' fdinfo requires root privileges. This limits
the use of the interface to debugging environments and is not suitable for
production builds. Granting root privileges even to a system process
increases the attack surface and is highly undesirable.
Since fdinfo doesn't permit reading process memory and manipulating
process state, allow accessing fdinfo under PTRACE_MODE_READ_FSCRED.
Link: https://lkml.kernel.org/r/20210308170651.919148-1-kaleshsingh@google.com Signed-off-by: Kalesh Singh <kaleshsingh@google.com> Suggested-by: Jann Horn <jannh@google.com> Acked-by: Christian König <christian.koenig@amd.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Alexey Gladkov <gladkov.alexey@gmail.com> Cc: Andrei Vagin <avagin@gmail.com> Cc: Bernd Edlinger <bernd.edlinger@hotmail.de> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Helge Deller <deller@gmx.de> Cc: Hridya Valsaraju <hridya@google.com> Cc: James Morris <jamorris@linux.microsoft.com> Cc: Jeff Vander Stoep <jeffv@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michel Lespinasse <walken@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Szabolcs Nagy <szabolcs.nagy@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Now that proc_ops are separate from file_operations and other operations
it easy to check all instances to have ->proc_lseek hook and remove check
in main code.
Currently the pde_is_permanent() check is being run on root multiple times
rather than on the next proc directory entry. This looks like a
copy-paste error. Fix this by replacing root with next.
Addresses-Coverity: ("Copy-paste error") Link: https://lkml.kernel.org/r/20210318122633.14222-1-colin.king@canonical.com Fixes: d919b33dafb3 ("proc: faster open/read/close with "permanent" files") Signed-off-by: Colin Ian King <colin.king@canonical.com> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Greg Kroah-Hartman <gregkh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
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>
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>
Marco Elver [Tue, 13 Apr 2021 22:21:11 +0000 (08:21 +1000)]
kfence: zero guard page after out-of-bounds access
After an out-of-bounds accesses, zero the guard page before re-protecting
in kfence_guarded_free(). On one hand this helps make the failure mode of
subsequent out-of-bounds accesses more deterministic, but could also
prevent certain information leaks.
Link: https://lkml.kernel.org/r/20210312121653.348518-1-elver@google.com Signed-off-by: Marco Elver <elver@google.com> Acked-by: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Jann Horn <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Ira Weiny [Tue, 13 Apr 2021 22:21:06 +0000 (08:21 +1000)]
mm/highmem: Remove deprecated kmap_atomic
kmap_atomic() is being deprecated in favor of kmap_local_page().
Replace the uses of kmap_atomic() within the highmem code.
On profiling clear_huge_page() using ftrace an improvement of 62% was
observed on the below setup.
Setup:-
Below data has been collected on Qualcomm's SM7250 SoC THP enabled
(kernel v4.19.113) with only CPU-0(Cortex-A55) and CPU-7(Cortex-A76)
switched on and set to max frequency, also DDR set to perf governor.
FTRACE Data:-
Base data:-
Number of iterations: 48
Mean of allocation time: 349.5 us
std deviation: 74.5 us
v4 data:-
Number of iterations: 48
Mean of allocation time: 131 us
std deviation: 32.7 us
The following simple userspace experiment to allocate
100MB(BUF_SZ) of pages and writing to it gave us a good insight,
we observed an improvement of 42% in allocation and writing timings.
-------------------------------------------------------------
Test code snippet
-------------------------------------------------------------
clock_start();
buf = malloc(BUF_SZ); /* Allocate 100 MB of memory */
Base data:-
Number of iterations: 100
Mean of allocation time: 31831 us
std deviation: 4286 us
v4 data:-
Number of iterations: 100
Mean of allocation time: 18193 us
std deviation: 4915 us
Link: https://lkml.kernel.org/r/20210204073255.20769-2-prathu.baronia@oneplus.com Signed-off-by: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Prathu Baronia <prathu.baronia@oneplus.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Ira Weiny [Tue, 13 Apr 2021 22:21:06 +0000 (08:21 +1000)]
btrfs: use memzero_page() instead of open coded kmap pattern
There are many places where kmap/memset/kunmap patterns occur.
Use the newly lifted memzero_page() to eliminate direct uses of kmap and
leverage the new core functions use of kmap_local_page().
The development of this patch was aided by the following coccinelle
script:
// <smpl>
// SPDX-License-Identifier: GPL-2.0-only
// Find kmap/memset/kunmap pattern and replace with memset*page calls
//
// NOTE: Offsets and other expressions may be more complex than what the script
// will automatically generate. Therefore a catchall rule is provided to find
// the pattern which then must be evaluated by hand.
//
// Confidence: Low
// Copyright: (C) 2021 Intel Corporation
// URL: http://coccinelle.lip6.fr/
// Comments:
// Options:
//
// Then the memset pattern
//
@ memset_rule1 @
expression page, V, L, Off;
identifier ptr;
type VP;
@@
// Remove any pointers left unused
@
depends on memset_rule1
@
identifier memset_rule1.ptr;
type VP, VP1;
@@
-VP ptr;
... when != ptr;
? VP1 ptr;
//
// Catch all
//
@ memset_rule2 @
expression page;
identifier ptr;
expression GenTo, GenSize, GenValue;
type VP;
@@
(
-VP ptr = kmap(page);
|
-ptr = kmap(page);
|
-VP ptr = kmap_atomic(page);
|
-ptr = kmap_atomic(page);
)
<+...
(
//
// Some call sites have complex expressions within the memset/memcpy
// The follow are catch alls which need to be evaluated by hand.
//
-memset(GenTo, 0, GenSize);
+memzero_pageExtra(page, GenTo, GenSize);
|
-memset(GenTo, GenValue, GenSize);
+memset_pageExtra(page, GenValue, GenTo, GenSize);
)
...+>
(
-kunmap(page);
|
-kunmap_atomic(ptr);
)
// Remove any pointers left unused
@
depends on memset_rule2
@
identifier memset_rule2.ptr;
type VP, VP1;
@@
-VP ptr;
... when != ptr;
? VP1 ptr;
// </smpl>
Link: https://lkml.kernel.org/r/20210309212137.2610186-4-ira.weiny@intel.com Signed-off-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: David Sterba <dsterba@suse.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Ira Weiny [Tue, 13 Apr 2021 22:21:06 +0000 (08:21 +1000)]
iov_iter: lift memzero_page() to highmem.h
Patch series "btrfs: Convert kmap/memset/kunmap to memzero_user()".
Lifting memzero_user(), convert it to kmap_local_page() and then use it in
btrfs.
This patch (of 3):
memzero_page() can replace the kmap/memset/kunmap pattern in other places
in the code. While zero_user() has the same interface it is not the same
call and its use should be limited and some of those calls may be better
converted from zero_user() to memzero_page().[1] But that is not addressed
in this series.
Zhiyuan Dai [Tue, 13 Apr 2021 22:21:05 +0000 (08:21 +1000)]
mm/zswap.c: switch from strlcpy to strscpy
strlcpy is marked as deprecated in Documentation/process/deprecated.rst,
and there is no functional difference when the caller expects truncation
(when not checking the return value). strscpy is relatively better as it
also avoids scanning the whole source string.
Link: https://lkml.kernel.org/r/1614227981-20367-1-git-send-email-daizhiyuan@phytium.com.cn Signed-off-by: Zhiyuan Dai <daizhiyuan@phytium.com.cn> Cc: Seth Jennings <sjenning@redhat.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Vitaly Wool <vitaly.wool@konsulko.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
mm/memory_hotplug: make unpopulated zones PCP structures unreachable during hot remove
zone_pcp_reset allegedly protects against a race with drain_pages using
local_irq_save but this is bogus. local_irq_save only operates on the
local CPU. If memory hotplug is running on CPU A and drain_pages is
running on CPU B, disabling IRQs on CPU A does not affect CPU B and offers
no protection.
This patch deletes IRQ disable/enable on the grounds that IRQs protect
nothing and assumes the existing hotplug paths guarantees the PCP cannot
be used after zone_pcp_enable(). That should be the case already because
all the pages have been freed and there is no page to put on the PCP
lists.
Link: https://lkml.kernel.org/r/20210412090346.GQ3697@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> Cc: Minchan Kim <minchan@kernel.org> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Enable arm64 platform to use the MHP_MEMMAP_ON_MEMORY feature.
Link: https://lkml.kernel.org/r/20210319092635.6214-6-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Enable x86_64 platform to use the MHP_MEMMAP_ON_MEMORY feature.
Link: https://lkml.kernel.org/r/20210319092635.6214-5-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Oscar Salvador [Tue, 13 Apr 2021 22:21:04 +0000 (08:21 +1000)]
mm,memory_hotplug: add kernel boot option to enable memmap_on_memory
Self stored memmap leads to a sparse memory situation which is unsuitable
for workloads that requires large contiguous memory chunks, so make this
an opt-in which needs to be explicitly enabled.
To control this, let memory_hotplug have its own memory space, as
suggested by David, so we can add memory_hotplug.memmap_on_memory
parameter.
Link: https://lkml.kernel.org/r/20210319092635.6214-4-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Oscar Salvador [Tue, 13 Apr 2021 22:21:04 +0000 (08:21 +1000)]
acpi,memhotplug: enable MHP_MEMMAP_ON_MEMORY when supported
Let the caller check whether it can pass MHP_MEMMAP_ON_MEMORY by checking
mhp_supports_memmap_on_memory(). MHP_MEMMAP_ON_MEMORY can only be set in
case ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE is enabled, the architecture
supports altmap, and the range to be added spans a single memory block.
Link: https://lkml.kernel.org/r/20210319092635.6214-3-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pavel Tatashin <pasha.tatashin@soleen.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>
Oscar Salvador [Tue, 13 Apr 2021 22:21:03 +0000 (08:21 +1000)]
mm,memory_hotplug: allocate memmap from the added memory range
Patch series "Allocate memmap from hotadded memory (per device)", v5.
The primary goal of this patchset is to reduce memory overhead of the
hot-added memory (at least for SPARSEMEM_VMEMMAP memory model). The
current way we use to populate memmap (struct page array) has two main
drawbacks:
a) it consumes an additional memory until the hotadded memory itself is
onlined and
b) memmap might end up on a different numa node which is especially
true for movable_node configuration.
c) due to fragmentation we might end up populating memmap with base
pages
One way to mitigate all these issues is to simply allocate memmap array
(which is the largest memory footprint of the physical memory hotplug)
from the hot-added memory itself. SPARSEMEM_VMEMMAP memory model allows
us to map any pfn range so the memory doesn't need to be online to be
usable for the array. See patch 3 for more details. This feature is only
usable when CONFIG_SPARSEMEM_VMEMMAP is set.
[Overall design]:
Implementation wise we reuse vmem_altmap infrastructure to override the
default allocator used by vmemap_populate. memory_block structure gained
a new field called nr_vmemmap_pages. This plays well for two reasons:
1) {offline/online}_pages know the difference between start_pfn and
buddy_start_pfn, which is start_pfn + nr_vmemmap_pages. In this way
all isolation/migration operations are done to within the right range
of memory without vmemmap pages. This allows us for a much cleaner
handling.
2) In try_remove_memory, we construct a new vmemap_altmap struct with
the right information based on memory_block->nr_vmemap_pages, so we end
up calling vmem_altmap_free instead of free_pagetable when removing the
memory.
This patch (of 5):
Physical memory hotadd has to allocate a memmap (struct page array) for
the newly added memory section. Currently, alloc_pages_node() is used for
those allocations.
This has some disadvantages:
a) an existing memory is consumed for that purpose
(eg: ~2MB per 128MB memory section on x86_64)
b) if the whole node is movable then we have off-node struct pages
which has performance drawbacks.
c) It might be there are no PMD_ALIGNED chunks so memmap array gets
populated with base pages.
This can be improved when CONFIG_SPARSEMEM_VMEMMAP is enabled.
Vmemap page tables can map arbitrary memory. That means that we can
simply use the beginning of each memory section and map struct pages
there. struct pages which back the allocated space then just need to be
treated carefully.
Implementation wise we will reuse vmem_altmap infrastructure to override
the default allocator used by __populate_section_memmap. Part of the
implementation also relies on memory_block structure gaining a new field
which specifies the number of vmemmap_pages at the beginning. This comes
in handy as in {online,offline}_pages, all the isolation and migration is
being done on (buddy_start_pfn, end_pfn] range, being buddy_start_pfn =
start_pfn + nr_vmemmap_pages.
In this way, we have:
[start_pfn, buddy_start_pfn - 1] = Initialized and PageReserved
[buddy_start_pfn, end_pfn - 1] = Initialized and sent to buddy
Hot-remove:
We need to be careful when removing memory, as adding and removing
memory needs to be done with the same granularity. To check that this
assumption is not violated, we check the memory range we want to remove
and if a) any memory block has vmemmap pages and b) the range spans more
than a single memory block, we scream out loud and refuse to proceed.
If all is good and the range was using memmap on memory (aka vmemmap
pages), we construct an altmap structure so free_hugepage_table does the
right thing and calls vmem_altmap_free instead of free_pagetable.
Link: https://lkml.kernel.org/r/20210319092635.6214-1-osalvador@suse.de Link: https://lkml.kernel.org/r/20210319092635.6214-2-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Pavel Tatashin [Tue, 13 Apr 2021 22:21:03 +0000 (08:21 +1000)]
selftests/vm: gup_test: test faulting in kernel, and verify pinnable pages
When pages are pinned they can be faulted in userland and migrated, and
they can be faulted right in kernel without migration.
In either case, the pinned pages must end-up being pinnable (not movable).
Add a new test to gup_test, to help verify that the gup/pup
(get_user_pages() / pin_user_pages()) behavior with respect to pinnable
and movable pages is reasonable and correct. Specifically, provide a way
to:
1) Verify that only "pinnable" pages are pinned. This is checked
automatically for you.
2) Verify that gup/pup performance is reasonable. This requires
comparing benchmarks between doing gup/pup on pages that have been
pre-faulted in from user space, vs. doing gup/pup on pages that are
not faulted in until gup/pup time (via FOLL_TOUCH). This decision is
controlled with the new -z command line option.
Link: https://lkml.kernel.org/r/20210215161349.246722-15-pasha.tatashin@soleen.com Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: James Morris <jmorris@namei.org> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sashal@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Tyler Hicks <tyhicks@linux.microsoft.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>
projects / users / jedix / linux-maple.git / log