All in-kernel users of %n in format strings have now been removed and
the %n directive is ignored. Remove the handling of %n so that it is
treated the same as any other invalid format string directive. Keep a
warning in place to deter new instances of %n in format strings.
Signed-off-by: Ryan Mallon <rmallon@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Code that is obj-y (always built-in) or dependent on a bool Kconfig
(built-in or absent) can never be modular. So using module_init as an
alias for __initcall can be somewhat misleading.
Fix these up now, so that we can relocate module_init from init.h into
module.h in the future. If we don't do this, we'd have to add module.h
to obviously non-modular code, and that would be a worse thing.
The audit targets the following module_init users for change:
kernel/user.c obj-y
kernel/kexec.c bool KEXEC (one instance per arch)
kernel/profile.c bool PROFILING
kernel/hung_task.c bool DETECT_HUNG_TASK
kernel/sched/stats.c bool SCHEDSTATS
kernel/user_namespace.c bool USER_NS
Note that direct use of __initcall is discouraged, vs. one of the
priority categorized subgroups. As __initcall gets mapped onto
device_initcall, our use of subsys_initcall (which makes sense for these
files) will thus change this registration from level 6-device to level
4-subsys (i.e. slightly earlier). However no observable impact of that
difference has been observed during testing.
Also, two instances of missing ";" at EOL are fixed in kexec.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The Makefile is designed to use the host toolchain so it may be unsafe
to build the tests if the kernel has been configured and built for
another architecture. This fixes a build problem when the kernel has
been configured and built for the MIPS architecture but the host is not
MIPS (cross-compiled). The MIPS syscalls are only defined if one of the
following is true:
1) _MIPS_SIM == _MIPS_SIM_ABI64
2) _MIPS_SIM == _MIPS_SIM_ABI32
3) _MIPS_SIM == _MIPS_SIM_NABI32
Of course, none of these make sense on a non-MIPS toolchain and the
following build problem occurs when building on a non-MIPS host.
linux/usr/include/linux/kexec.h:50: userspace cannot reference function or variable defined in the kernel
samples/seccomp/bpf-direct.c: In function `emulator':
samples/seccomp/bpf-direct.c:76:17: error: `__NR_write' undeclared (first use in this function)
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use the more natural return of bool for these tests.
No difference observed in .o files produced by gcc for x86.
Remove the dentry description of kernel pointers left over from the 90's
and 2002's cleanup move of parts of fs.h to err.h.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Most of the mechanical portions of SubmittingPatches exist to help patch
submitters replicate the output of git. Mention this explicitly, both
as a reminder that git will help with this process, and as signposting
to let git users know what they can safely skip.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Rob Landley <rob@landley.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Most commit messages use this style, and the recommendation frequently
comes up in discussions (especially in response to patches that don't
use it), but that recommendation doesn't actually appear anywhere in
Documentation. Add this style guideline to SubmittingPatches, using the
description from git's SubmittingPatches.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Rob Landley <rob@landley.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
uselib hasn't been used since libc5; glibc does not use it. Support
turning it off.
When disabled, also omit the load_elf_library implementation from
binfmt_elf.c, which only uselib invokes.
bloat-o-meter:
add/remove: 0/4 grow/shrink: 0/1 up/down: 0/-785 (-785)
function old new delta
padzero 39 36 -3
uselib_flags 20 - -20
sys_uselib 168 - -168
SyS_uselib 168 - -168
load_elf_library 426 - -426
The new CONFIG_USELIB defaults to `y'.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After commit 6307f8fee2 ("security: remove dead hook task_setgroups"),
set_groups will always return zero, so we could just remove return value
of set_groups.
This patch reduces code size, and simplfies code to use set_groups,
because we don't need to check its return value any more.
[akpm@linux-foundation.org: remove obsolete claims from set_groups() comment]
Signed-off-by: Wang YanQing <udknight@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
sys_sysfs is an obsolete system call no longer supported by libc.
- This patch adds a default CONFIG_SYSFS_SYSCALL=y
- Option can be turned off in expert mode.
- cond_syscall added to kernel/sys_ni.c
[akpm@linux-foundation.org: tweak Kconfig help text]
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently max_sane_readahead() returns zero on the cpu whose NUMA node
has no local memory which leads to readahead failure. Fix this
readahead failure by returning minimum of (requested pages, 512). Users
running applications on a memory-less cpu which needs readahead such as
streaming application see considerable boost in the performance.
Result:
fadvise experiment with FADV_WILLNEED on a PPC machine having memoryless
CPU with 1GB testfile (12 iterations) yielded around 46.66% improvement.
fadvise experiment with FADV_WILLNEED on a x240 machine with 1GB
testfile 32GB* 4G RAM numa machine (12 iterations) showed no impact on
the normal NUMA cases w/ patch.
Kernel Avg Stddev
base 7.4975 3.92%
patched 7.4174 3.26%
[Andrew: making return value PAGE_SIZE independent]
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We release the slab_mutex while calling sysfs_slab_add from
__kmem_cache_create since commit 66c4c35c6b ("slub: Do not hold
slub_lock when calling sysfs_slab_add()"), because kobject_uevent called
by sysfs_slab_add might block waiting for the usermode helper to exec,
which would result in a deadlock if we took the slab_mutex while
executing it.
However, apart from complicating synchronization rules, releasing the
slab_mutex on kmem cache creation can result in a kmemcg-related race.
The point is that we check if the memcg cache exists before going to
__kmem_cache_create, but register the new cache in memcg subsys after
it. Since we can drop the mutex there, several threads can see that the
memcg cache does not exist and proceed to creating it, which is wrong.
Fortunately, recently kobject_uevent was patched to call the usermode
helper with the UMH_NO_WAIT flag, making the deadlock impossible.
Therefore there is no point in releasing the slab_mutex while calling
sysfs_slab_add, so let's simplify kmem_cache_create synchronization and
fix the kmemcg-race mentioned above by holding the slab_mutex during the
whole cache creation path.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Greg KH <greg@kroah.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently kobject_uevent has somewhat unpredictable semantics. The
point is, since it may call a usermode helper and wait for it to execute
(UMH_WAIT_EXEC), it is impossible to say for sure what lock dependencies
it will introduce for the caller - strictly speaking it depends on what
fs the binary is located on and the set of locks fork may take. There
are quite a few kobject_uevent's users that do not take this into
account and call it with various mutexes taken, e.g. rtnl_mutex,
net_mutex, which might potentially lead to a deadlock.
Since there is actually no reason to wait for the usermode helper to
execute there, let's make kobject_uevent start the helper asynchronously
with the aid of the UMH_NO_WAIT flag.
Personally, I'm interested in this, because I really want kobject_uevent
to be called under the slab_mutex in the slub implementation as it used
to be some time ago, because it greatly simplifies synchronization and
automatically fixes a kmemcg-related race. However, there was a
deadlock detected on an attempt to call kobject_uevent under the
slab_mutex (see https://lkml.org/lkml/2012/1/14/45), which was reported
to be fixed by releasing the slab_mutex for kobject_uevent.
Unfortunately, there was no information about who exactly blocked on the
slab_mutex causing the usermode helper to stall, neither have I managed
to find this out or reproduce the issue.
BTW, this is not the first attempt to make kobject_uevent use
UMH_NO_WAIT. Previous one was made by commit f520360d93 ("kobject:
don't block for each kobject_uevent"), but it was wrong (it passed
arguments allocated on stack to async thread) so it was reverted in
05f54c13cd ("Revert "kobject: don't block for each kobject_uevent".").
It targeted on speeding up the boot process though.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Greg KH <greg@kroah.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is plenty of anecdotal evidence and a load of blog posts
suggesting that using "drop_caches" periodically keeps your system
running in "tip top shape". Perhaps adding some kernel documentation
will increase the amount of accurate data on its use.
If we are not shrinking caches effectively, then we have real bugs.
Using drop_caches will simply mask the bugs and make them harder to
find, but certainly does not fix them, nor is it an appropriate
"workaround" to limit the size of the caches. On the contrary, there
have been bug reports on issues that turned out to be misguided use of
cache dropping.
Dropping caches is a very drastic and disruptive operation that is good
for debugging and running tests, but if it creates bug reports from
production use, kernel developers should be aware of its use.
Add a bit more documentation about it, a syslog message to track down
abusers, and vmstat drop counters to help analyze problem reports.
[akpm@linux-foundation.org: checkpatch fixes]
[hannes@cmpxchg.org: add runtime suppression control]
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch removes read_cache_page_async() which wasn't really needed
anywhere and simplifies the code around it a bit.
read_cache_page_async() is useful when we want to read a page into the
cache without waiting for it to complete. This happens when the
appropriate callback 'filler' doesn't complete its read operation and
releases the page lock immediately, and instead queues a different
completion routine to do that. This never actually happened anywhere in
the code.
read_cache_page_async() had 3 different callers:
- read_cache_page() which is the sync version, it would just wait for
the requested read to complete using wait_on_page_read().
- JFFS2 would call it from jffs2_gc_fetch_page(), but the filler
function it supplied doesn't do any async reads, and would complete
before the filler function returns - making it actually a sync read.
- CRAMFS would call it using the read_mapping_page_async() wrapper, with
a similar story to JFFS2 - the filler function doesn't do anything that
reminds async reads and would always complete before the filler function
returns.
To sum it up, the code in mm/filemap.c never took advantage of having
read_cache_page_async(). While there are filler callbacks that do async
reads (such as the block one), we always called it with the
read_cache_page().
This patch adds a mandatory wait for read to complete when adding a new
page to the cache, and removes read_cache_page_async() and its wrappers.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I've realized that there's no need for do_huge_pmd_wp_zero_page_fallback().
We can just split zero page with split_huge_page_pmd() and return
VM_FAULT_FALLBACK. handle_pte_fault() will handle write-protection
fault for us.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce do_shared_fault(). The function does what do_fault() does for
write faults to shared mappings
Unlike do_fault(), do_shared_fault() is relatively clean and
straight-forward.
Old do_fault() is not needed anymore. Let it die.
[lliubbo@gmail.com: fix NULL pointer dereference]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Ryan Mallon
Daeseok Youn
Paul Gortmaker
Andrew Morton
Serge Hallyn
Markos Chandras
Joe Perches
Josh Triplett
Wang YanQing
Fabian Frederick
Rashika Kheria
Raghavendra K T
Vladimir Davydov
Dave Hansen
Sasha Levin
Kirill A. Shutemov