autofs does not expect the pipe it is given to have O_NONBLOCK set -
specifically if __kernel_write() in autofs_write() returns -EAGAIN, this
is treated as a fatal error and the pipe is closed.
For safety autofs should, therefore, clear the O_NONBLOCK flag.
Releases of systemd prior to 8th February 2019 used
pipe2(p, O_NONBLOCK|O_CLOEXEC)
and thus (inadvertently) set this flag.
Link: http://lkml.kernel.org/r/154993550902.3321.1183632970046073478.stgit@pluto-themaw-net
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add an autofs file system mount option that can be used to provide a
generic indicator to applications that the mount entry should be ignored
when displaying mount information.
In other OSes that provide autofs and that provide a mount list to user
space based on the kernel mount list a no-op mount option ("ignore" is
the one use on the most common OS) is allowed so that autofs file system
users can optionally use it.
The idea is that it be used by user space programs to exclude autofs
mounts from consideration when reading the mounts list.
Prior to the change to link /etc/mtab to /proc/self/mounts all I needed
to do to achieve this was to use mount(2) and not update the mtab but
now that no longer works.
I know the symlinking happened a long time ago and I considered doing
this then but, at the time I couldn't remember the commonly used option
name and thought persuading the various utility maintainers would be too
hard.
But now I have a RHEL request to do this for compatibility for a widely
used product so I want to go ahead with it and try and enlist the help
of some utility package maintainers.
Clearly, without the option nothing can be done so it's at least a
start.
Link: http://lkml.kernel.org/r/154725123970.11260.6113771566924907275.stgit@pluto-themaw-net
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The goal of this patch is to reduce contention of ep_poll_callback()
which can be called concurrently from different CPUs in case of high
events rates and many fds per epoll. Problem can be very well
reproduced by generating events (write to pipe or eventfd) from many
threads, while consumer thread does polling. In other words this patch
increases the bandwidth of events which can be delivered from sources to
the poller by adding poll items in a lockless way to the list.
The main change is in replacement of the spinlock with a rwlock, which
is taken on read in ep_poll_callback(), and then by adding poll items to
the tail of the list using xchg atomic instruction. Write lock is taken
everywhere else in order to stop list modifications and guarantee that
list updates are fully completed (I assume that write side of a rwlock
does not starve, it seems qrwlock implementation has these guarantees).
The following are some microbenchmark results based on the test [1]
which starts threads which generate N events each. The test ends when
all events are successfully fetched by the poller thread:
spinlock
========
threads events/ms run-time ms
8 6402 12495
16 7045 22709
32 7395 43268
rwlock + xchg
=============
threads events/ms run-time ms
8 10038 7969
16 12178 13138
32 13223 24199
According to the results bandwidth of delivered events is significantly
increased, thus execution time is reduced.
This patch was tested with different sort of microbenchmarks and
artificial delays (e.g. "udelay(get_random_int() & 0xff)") introduced
in kernel on paths where items are added to lists.
[1] https://github.com/rouming/test-tools/blob/master/stress-epoll.c
Link: http://lkml.kernel.org/r/20190103150104.17128-5-rpenyaev@suse.de
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Original comment "Activate ep->ws since epi->ws may get deactivated at
any time" indeed sounds loud, but it is incorrect, because the path
where we check epi->ws is a path where insert to ovflist happens, i.e.
ep_scan_ready_list() has taken ep->mtx and waits for this callback to
finish, thus ep_modify() (which unregisters wakeup source) waits for
ep_scan_ready_list().
Here in this patch I simply call ep_pm_stay_awake_rcu(), which is a bit
extra for this path (indirectly protected by main ep->mtx, so even rcu
is not needed), but I do not want to create another naked
__ep_pm_stay_awake() variant only for this particular case, so rcu variant
is just better for all the cases.
Link: http://lkml.kernel.org/r/20190103150104.17128-4-rpenyaev@suse.de
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "use rwlock in order to reduce ep_poll_callback()
contention", v3.
The last patch targets the contention problem in ep_poll_callback(),
which can be very well reproduced by generating events (write to pipe or
eventfd) from many threads, while consumer thread does polling.
The following are some microbenchmark results based on the test [1]
which starts threads which generate N events each. The test ends when
all events are successfully fetched by the poller thread:
spinlock
========
threads events/ms run-time ms
8 6402 12495
16 7045 22709
32 7395 43268
rwlock + xchg
=============
threads events/ms run-time ms
8 10038 7969
16 12178 13138
32 13223 24199
According to the results bandwidth of delivered events is significantly
increased, thus execution time is reduced.
This patch (of 4):
All coming events are stored in FIFO order and this is also should be
applicable to ->ovflist, which originally is stack, i.e. LIFO.
Thus to keep correct FIFO order ->ovflist should reversed by adding
elements to the head of the read list but not to the tail.
Link: http://lkml.kernel.org/r/20190103150104.17128-2-rpenyaev@suse.de
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Presently C99 style comments are removed unconditionally before actual
patch validity check happens. This is a problem for some third party
projects which use checkpatch.pl but do not allow C99 style comments.
This patch adds yet another variable, named C99_COMMENT_TOLERANCE. If
it is included in the --ignore command line or config file options list,
C99 comments in the patch are reported as errors.
Tested by processing a patch with a C99 style comment, it passes the
check just fine unless '--ignore C99_COMMENT_TOLERANCE' is present in
.checkpatch.conf.
Link: http://lkml.kernel.org/r/20190110224957.25008-1-vbendeb@chromium.org
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Many new generic allocation functions like the kvmalloc family have been
added recently to the kernel.
The allocation functions test now includes:
o kvmalloc and variants
o kstrdup_const
o kmemdup_nul
o dma_alloc_coherent
o alloc_skb and variants
Add a separate $allocFunctions variable to help make the allocation
functions test a bit more readable.
Miscellanea:
o Use $allocFunctions in the unnecessary OOM message test and
add exclude uses with __GFP_NOWARN
o Use $allocFunctions in the unnecessary cast test
o Add the kvmalloc family to the preferred sizeof alloc style
foo = kvmalloc(sizeof(*foo), ...)
Link: http://lkml.kernel.org/r/a5e60a2b93e10baf84af063f6c8e56402273105d.camel@perches.com
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>
In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
This patch fixes the following warning:
lib/assoc_array.c: In function `assoc_array_delete':
lib/assoc_array.c:1110:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
for (slot = 0; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
^~~
lib/assoc_array.c:1118:2: note: here
case assoc_array_walk_tree_empty:
^~~~
Warning level 3 was used: -Wimplicit-fallthrough=3
This patch is part of the ongoing efforts to enable
-Wimplicit-fallthrough.
Link: http://lkml.kernel.org/r/20190212212206.GA16378@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For the upcoming 'define the _ddebug descriptor in assembly', we need
all the descriptors in a translation unit to have distinct names
(because asm does not understand C scope). The easiest way to achieve
that is as usual with an extra level of macros, passing the identifier
to use to the innermost macro, generating it via __UNIQUE_ID or
something.
However, instead of repeating that exercise for dynamic_pr_debug,
dynamic_dev_dbg, dynamic_netdev_dbg and dynamic_hex_dump separately, we
can use the similarity between their bodies to implement them via a
common macro, _dynamic_func_call - though the hex_dump case requires a
slight variant, since print_hex_dump does not take the _ddebug
descriptor. We'll also get to use that variant elsewhere (btrfs).
Link: http://lkml.kernel.org/r/20190212214150.4807-11-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Jason Baron <jbaron@akamai.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that we store the passed-in string directly in ddebug_add_module, we
can use pointer equality instead of strcmp. This is a little more
efficient, but more importantly, this also makes the code somewhat more
correct:
Currently, if one loads and then unloads a module whose name happens to
match the KBUILD_MODNAME of some built-in functionality (which need not
even be modular at all), all of their dynamic debug entries vanish along
with those of the actual module. For example, loading and unloading a
core.ko hides all pr_debugs from drivers/base/core.c and other built-in
files called core.c (incidentally, there is an in-tree module whose name
is core, but I just tested this with an out-of-tree trivial one).
Link: http://lkml.kernel.org/r/20190212214150.4807-7-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Jason Baron <jbaron@akamai.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "various dynamic_debug patches", v4.
This started as an experiment to see how hard it would be to change the
four pointers in struct _ddebug into relative offsets, a la
CONFIG_GENERIC_BUG_RELATIVE_POINTERS, thus saving 16 bytes per pr_debug
site (and thus exactly making up for the extra space used by the
introduction of jump labels in 9049fc74). I stumbled on a few things
that are probably worth fixing regardless of whether that goal is deemed
worthwhile.
Back at v3 (in November), I redid the implementation on top of the fancy
new asm-macros stuff. Luckily enough, v3 didn't get picked up, since
the asm-macros were backed out again. I still want to do the
relative-pointers thing eventually, but we're close to the merge window
opening, so here's just most of the "incidental" patches, some of which
also serve as preparation for the relative pointers.
This patch (of 4):
dev_dbg_ratelimited tests the dynamic debug descriptor the old-fashioned
way, and doesn't utilize the static key/jump label implementation when
CONFIG_JUMP_LABEL is set. Use the DYNAMIC_DEBUG_BRANCH which is defined
appropriately.
Link: http://lkml.kernel.org/r/20190212214150.4807-2-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Jason Baron <jbaron@akamai.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
BUILD_BUG_ON() is a little annoying, since it cannot be used outside
function scope. So one cannot put assertions about the sizeof() a
struct next to the struct definition, but has to hide that in some more
or less arbitrary function.
Since gcc 4.6 (which is now also the required minimum), there is support
for the C11 _Static_assert in all C modes, including gnu89. So add a
simple wrapper for that.
_Static_assert() requires a message argument, which is usually quite
redundant (and I believe that bug got fixed at least in newer C++
standards), but we can easily work around that with a little macro
magic, making it optional.
For example, adding
static_assert(sizeof(struct printf_spec) == 8);
in vsprintf.c and modifying that struct to violate it, one gets
./include/linux/build_bug.h:78:41: error: static assertion failed: "sizeof(struct printf_spec) == 8"
#define __static_assert(expr, msg, ...) _Static_assert(expr, "" msg "")
godbolt.org suggests that _Static_assert() has been support by clang
since at least 3.0.0.
Link: http://lkml.kernel.org/r/20190208203015.29702-1-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit a2e5144538 ("kernel/hung_task.c: allow to set checking
interval separately from timeout") added hung_task_check_interval_secs,
setting a value different from hung_task_timeout_secs
echo 0 > /proc/sys/kernel/hung_task_panic
echo 120 > /proc/sys/kernel/hung_task_timeout_secs
echo 5 > /proc/sys/kernel/hung_task_check_interval_secs
causes confusing output as if the task was blocked for
hung_task_timeout_secs seconds from the previous report.
[ 399.395930] INFO: task kswapd0:75 blocked for more than 120 seconds.
[ 405.027637] INFO: task kswapd0:75 blocked for more than 120 seconds.
[ 410.659725] INFO: task kswapd0:75 blocked for more than 120 seconds.
[ 416.292860] INFO: task kswapd0:75 blocked for more than 120 seconds.
[ 421.932305] INFO: task kswapd0:75 blocked for more than 120 seconds.
Although we could update t->last_switch_time after sched_show_task(t) if
we want to report only every 120 seconds, reporting every 5 seconds
might not be very bad for monitoring after a problematic situation has
started. Thus, let's use continuously blocked time instead of updating
previously reported time.
[ 677.985011] INFO: task kswapd0:80 blocked for more than 122 seconds.
[ 693.856126] INFO: task kswapd0:80 blocked for more than 138 seconds.
[ 709.728075] INFO: task kswapd0:80 blocked for more than 154 seconds.
[ 725.600018] INFO: task kswapd0:80 blocked for more than 170 seconds.
[ 741.473133] INFO: task kswapd0:80 blocked for more than 186 seconds.
Link: http://lkml.kernel.org/r/1551175083-10669-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
sparse complains:
CHECK kernel/hung_task.c
kernel/hung_task.c:28:19: warning: symbol 'sysctl_hung_task_check_count' was not declared. Should it be static?
kernel/hung_task.c:42:29: warning: symbol 'sysctl_hung_task_timeout_secs' was not declared. Should it be static?
kernel/hung_task.c:47:29: warning: symbol 'sysctl_hung_task_check_interval_secs' was not declared. Should it be static?
kernel/hung_task.c:49:19: warning: symbol 'sysctl_hung_task_warnings' was not declared. Should it be static?
kernel/hung_task.c:61:28: warning: symbol 'sysctl_hung_task_panic' was not declared. Should it be static?
kernel/hung_task.c:219:5: warning: symbol 'proc_dohung_task_timeout_secs' was not declared. Should it be static?
Add the appropriate header file to provide declarations.
Link: http://lkml.kernel.org/r/467.1548649525@turing-police.cc.vt.edu
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The single quotation marks around "const" were causing a documentation
markup warning with reST. Instead of fixing that warning, just delete
that comment line and the gcc-3.3 hack of using "const" in the roundup()
macro since gcc-3.3 is no longer supported for kernel builds.
I did around 20 different $arch builds with no problems, but we'll just
have to see if this causes problems for anyone else out there.
Link: http://lkml.kernel.org/r/ec5dcf72-7c3e-3513-af0c-4003ed598854@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use DEFINE_DEBUGFS_ATTRIBUTE rather than DEFINE_SIMPLE_ATTRIBUTE for
debugfs files.
Semantic patch information:
Rationale: DEFINE_SIMPLE_ATTRIBUTE + debugfs_create_file()
imposes some significant overhead as compared to
DEFINE_DEBUGFS_ATTRIBUTE + debugfs_create_file_unsafe().
Generated by: scripts/coccinelle/api/debugfs/debugfs_simple_attr.cocci
The _unsafe() part suggests that some of them "safeness
responsibilities" are now panic.c responsibilities. The patch is OK
since panic's clear_warn_once_fops struct file_operations is safe
against removal, so we don't have to use otherwise necessary
debugfs_file_get()/debugfs_file_put().
[sergey.senozhatsky.work@gmail.com: changelog addition]
Link: http://lkml.kernel.org/r/1545990861-158097-1-git-send-email-yuehaibing@huawei.com
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Petr Mladek <pmladek@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull x86 UV updates from Ingo Molnar:
"Three UV related cleanups"
* 'x86-uv-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/platform/UV: Use efi_enabled() instead of test_bit()
x86/platform/UV: Remove uv_bios_call_reentrant()
x86/platform/UV: Remove unnecessary #ifdef CONFIG_EFI
Pull x86 platform update from Ingo Molnar:
"A defconfig update"
* 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/defconfig: Enable EFI stub, mixed mode and BGRT
Pull x86 mm cleanup from Ingo Molnar:
"A single GUP cleanup"
* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
mm/gup: Remove the 'write' parameter from gup_fast_permitted()
