Pull misc updates from Andrew Morton:
"The non-MM patch queue for this merge window.
Not a lot of material this cycle. Many singleton patches against
various subsystems. Most notably some maintenance work in ocfs2
and initramfs"
* tag 'mm-nonmm-stable-2022-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (65 commits)
kcov: update pos before writing pc in trace function
ocfs2: dlmfs: fix error handling of user_dlm_destroy_lock
ocfs2: dlmfs: don't clear USER_LOCK_ATTACHED when destroying lock
fs/ntfs: remove redundant variable idx
fat: remove time truncations in vfat_create/vfat_mkdir
fat: report creation time in statx
fat: ignore ctime updates, and keep ctime identical to mtime in memory
fat: split fat_truncate_time() into separate functions
MAINTAINERS: add Muchun as a memcg reviewer
proc/sysctl: make protected_* world readable
ia64: mca: drop redundant spinlock initialization
tty: fix deadlock caused by calling printk() under tty_port->lock
relay: remove redundant assignment to pointer buf
fs/ntfs3: validate BOOT sectors_per_clusters
lib/string_helpers: fix not adding strarray to device's resource list
kernel/crash_core.c: remove redundant check of ck_cmdline
ELF, uapi: fixup ELF_ST_TYPE definition
ipc/mqueue: use get_tree_nodev() in mqueue_get_tree()
ipc: update semtimedop() to use hrtimer
ipc/sem: remove redundant assignments
...
Once kthread printing is available, console printing will no longer
occur in the context of the printk caller. However, there are some
special contexts where it is desirable for the printk caller to
directly print out kernel messages. Using pr_flush() to wait for
threaded printers is only possible if the caller is in a sleepable
context and the kthreads are active. That is not always the case.
Introduce printk_prefer_direct_enter() and printk_prefer_direct_exit()
functions to explicitly (and globally) activate/deactivate preferred
direct console printing. The term "direct console printing" refers to
printing to all enabled consoles from the context of the printk
caller. The term "prefer" is used because this type of printing is
only best effort. If the console is currently locked or other
printers are already actively printing, the printk caller will need
to rely on the other contexts to handle the printing.
This preferred direct printing is how all printing has been handled
until now (unless it was explicitly deferred).
When kthread printing is introduced, there may be some unanticipated
problems due to kthreads being unable to flush important messages.
In order to minimize such risks, preferred direct printing is
activated for the primary important messages when the system
experiences general types of major errors. These are:
- emergency reboot/shutdown
- cpu and rcu stalls
- hard and soft lockups
- hung tasks
- warn
- sysrq
Note that since kthread printing does not yet exist, no behavior
changes result from this commit. This is only implementing the
counter and marking the various places where preferred direct
printing is active.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org> # for RCU
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-13-john.ogness@linutronix.de
Merge more updates from Andrew Morton:
"190 patches.
Subsystems affected by this patch series: mm (hugetlb, userfaultfd,
vmscan, kconfig, proc, z3fold, zbud, ras, mempolicy, memblock,
migration, thp, nommu, kconfig, madvise, memory-hotplug, zswap,
zsmalloc, zram, cleanups, kfence, and hmm), procfs, sysctl, misc,
core-kernel, lib, lz4, checkpatch, init, kprobes, nilfs2, hfs,
signals, exec, kcov, selftests, compress/decompress, and ipc"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (190 commits)
ipc/util.c: use binary search for max_idx
ipc/sem.c: use READ_ONCE()/WRITE_ONCE() for use_global_lock
ipc: use kmalloc for msg_queue and shmid_kernel
ipc sem: use kvmalloc for sem_undo allocation
lib/decompressors: remove set but not used variabled 'level'
selftests/vm/pkeys: exercise x86 XSAVE init state
selftests/vm/pkeys: refill shadow register after implicit kernel write
selftests/vm/pkeys: handle negative sys_pkey_alloc() return code
selftests/vm/pkeys: fix alloc_random_pkey() to make it really, really random
kcov: add __no_sanitize_coverage to fix noinstr for all architectures
exec: remove checks in __register_bimfmt()
x86: signal: don't do sas_ss_reset() until we are certain that sigframe won't be abandoned
hfsplus: report create_date to kstat.btime
hfsplus: remove unnecessary oom message
nilfs2: remove redundant continue statement in a while-loop
kprobes: remove duplicated strong free_insn_page in x86 and s390
init: print out unknown kernel parameters
checkpatch: do not complain about positive return values starting with EPOLL
checkpatch: improve the indented label test
checkpatch: scripts/spdxcheck.py now requires python3
...
Commit 32927393dc ("sysctl: pass kernel pointers to ->proc_handler")
removed various __user annotations from function signatures as part of
its refactoring.
It also removed the __user annotation for proc_dohung_task_timeout_secs()
at its declaration in sched/sysctl.h, but not at its definition in
kernel/hung_task.c.
Hence, sparse complains:
kernel/hung_task.c:271:5: error: symbol 'proc_dohung_task_timeout_secs' redeclared with different type (incompatible argument 3 (different address spaces))
Adjust the annotation at the definition fitting to that refactoring to make
sparse happy again, which also resolves this warning from sparse:
kernel/hung_task.c:277:52: warning: incorrect type in argument 3 (different address spaces)
kernel/hung_task.c:277:52: expected void *
kernel/hung_task.c:277:52: got void [noderef] __user *buffer
No functional change. No change in object code.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ignatov <rdna@fb.com>
Link: https://lkml.kernel.org/r/20201028130541.20320-1-lukas.bulwahn@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 401c636a0e ("kernel/hung_task.c: show all hung tasks before
panic") introduced a change in that we started to show all CPUs
backtraces when a hung task is detected _and_ the sysctl/kernel
parameter "hung_task_panic" is set. The idea is good, because usually
when observing deadlocks (that may lead to hung tasks), the culprit is
another task holding a lock and not necessarily the task detected as
hung.
The problem with this approach is that dumping backtraces is a slightly
expensive task, specially printing that on console (and specially in
many CPU machines, as servers commonly found nowadays). So, users that
plan to collect a kdump to investigate the hung tasks and narrow down
the deadlock definitely don't need the CPUs backtrace on dmesg/console,
which will delay the panic and pollute the log (crash tool would easily
grab all CPUs traces with 'bt -a' command).
Also, there's the reciprocal scenario: some users may be interested in
seeing the CPUs backtraces but not have the system panic when a hung
task is detected. The current approach hence is almost as embedding a
policy in the kernel, by forcing the CPUs backtraces' dump (only) on
hung_task_panic.
This patch decouples the panic event on hung task from the CPUs
backtraces dump, by creating (and documenting) a new sysctl called
"hung_task_all_cpu_backtrace", analog to the approach taken on soft/hard
lockups, that have both a panic and an "all_cpu_backtrace" sysctl to
allow individual control. The new mechanism for dumping the CPUs
backtraces on hung task detection respects "hung_task_warnings" by not
dumping the traces in case there's no warnings left.
Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: http://lkml.kernel.org/r/20200327223646.20779-1-gpiccoli@canonical.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add SPDX license identifiers to all files which:
- Have no license information of any form
- Have EXPORT_.*_SYMBOL_GPL inside which was used in the
initial scan/conversion to ignore the file
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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>
Based on commit 401c636a0e ("kernel/hung_task.c: show all hung tasks
before panic"), we could get the call stack of hung task.
However, if the console loglevel is not high, we still can not see the
useful panic information in practice, and in most cases users don't set
console loglevel to high level.
This patch is to force console verbose before system panic, so that the
real useful information can be seen in the console, instead of being
like the following, which doesn't have hung task information.
INFO: task init:1 blocked for more than 120 seconds.
Tainted: G U W 4.19.0-quilt-2e5dc0ac-g51b6c21d76cc #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Kernel panic - not syncing: hung_task: blocked tasks
CPU: 2 PID: 479 Comm: khungtaskd Tainted: G U W 4.19.0-quilt-2e5dc0ac-g51b6c21d76cc #1
Call Trace:
dump_stack+0x4f/0x65
panic+0xde/0x231
watchdog+0x290/0x410
kthread+0x12c/0x150
ret_from_fork+0x35/0x40
reboot: panic mode set: p,w
Kernel Offset: 0x34000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
Link: http://lkml.kernel.org/r/27240C0AC20F114CBF8149A2696CBE4A6015B675@SHSMSX101.ccr.corp.intel.com
Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It is possible to observe hung_task complaints when system goes to
suspend-to-idle state:
# echo freeze > /sys/power/state
PM: Syncing filesystems ... done.
Freezing user space processes ... (elapsed 0.001 seconds) done.
OOM killer disabled.
Freezing remaining freezable tasks ... (elapsed 0.002 seconds) done.
sd 0:0:0:0: [sda] Synchronizing SCSI cache
INFO: task bash:1569 blocked for more than 120 seconds.
Not tainted 4.19.0-rc3_+ #687
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
bash D 0 1569 604 0x00000000
Call Trace:
? __schedule+0x1fe/0x7e0
schedule+0x28/0x80
suspend_devices_and_enter+0x4ac/0x750
pm_suspend+0x2c0/0x310
Register a PM notifier to disable the detector on suspend and re-enable
back on wakeup.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Currently task hung checking interval is equal to timeout, as the result
hung is detected anywhere between timeout and 2*timeout. This is fine for
most interactive environments, but this hurts automated testing setups
(syzbot). In an automated setup we need to strictly order CPU lockup <
RCU stall < workqueue lockup < task hung < silent loss, so that RCU stall
is not detected as task hung and task hung is not detected as silent
machine loss. The large variance in task hung detection timeout requires
setting silent machine loss timeout to a very large value (e.g. if task
hung is 3 mins, then silent loss need to be set to ~7 mins). The
additional 3 minutes significantly reduce testing efficiency because
usually we crash kernel within a minute, and this can add hours to bug
localization process as it needs to do dozens of tests.
Allow setting checking interval separately from timeout. This allows to
set timeout to, say, 3 minutes, but checking interval to 10 secs.
The interval is controlled via a new hung_task_check_interval_secs sysctl,
similar to the existing hung_task_timeout_secs sysctl. The default value
of 0 results in the current behavior: checking interval is equal to
timeout.
[akpm@linux-foundation.org: update hung_task_timeout_max's comment]
Link: http://lkml.kernel.org/r/20180611111004.203513-1-dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
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>
When we get a hung task it can often be valuable to see _all_ the hung
tasks on the system before calling panic().
Quoting from https://syzkaller.appspot.com/text?tag=CrashReport&id=5316056503549952
----------------------------------------
INFO: task syz-executor0:6540 blocked for more than 120 seconds.
Not tainted 4.16.0+ #13
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0 D23560 6540 4521 0x80000004
Call Trace:
context_switch kernel/sched/core.c:2848 [inline]
__schedule+0x8fb/0x1ef0 kernel/sched/core.c:3490
schedule+0xf5/0x430 kernel/sched/core.c:3549
schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3607
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0xb7f/0x1810 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355
__blkdev_driver_ioctl block/ioctl.c:303 [inline]
blkdev_ioctl+0x1759/0x1e00 block/ioctl.c:601
ioctl_by_bdev+0xa5/0x110 fs/block_dev.c:2060
isofs_get_last_session fs/isofs/inode.c:567 [inline]
isofs_fill_super+0x2ba9/0x3bc0 fs/isofs/inode.c:660
mount_bdev+0x2b7/0x370 fs/super.c:1119
isofs_mount+0x34/0x40 fs/isofs/inode.c:1560
mount_fs+0x66/0x2d0 fs/super.c:1222
vfs_kern_mount.part.26+0xc6/0x4a0 fs/namespace.c:1037
vfs_kern_mount fs/namespace.c:2514 [inline]
do_new_mount fs/namespace.c:2517 [inline]
do_mount+0xea4/0x2b90 fs/namespace.c:2847
ksys_mount+0xab/0x120 fs/namespace.c:3063
SYSC_mount fs/namespace.c:3077 [inline]
SyS_mount+0x39/0x50 fs/namespace.c:3074
do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x42/0xb7
(...snipped...)
Showing all locks held in the system:
(...snipped...)
2 locks held by syz-executor0/6540:
#0: 00000000566d4c39 (&type->s_umount_key#49/1){+.+.}, at: alloc_super fs/super.c:211 [inline]
#0: 00000000566d4c39 (&type->s_umount_key#49/1){+.+.}, at: sget_userns+0x3b2/0xe60 fs/super.c:502 /* down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING); */
#1: 0000000043ca8836 (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355 /* mutex_lock_nested(&lo->lo_ctl_mutex, 1); */
(...snipped...)
3 locks held by syz-executor7/6541:
#0: 0000000043ca8836 (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355 /* mutex_lock_nested(&lo->lo_ctl_mutex, 1); */
#1: 000000007bf3d3f9 (&bdev->bd_mutex){+.+.}, at: blkdev_reread_part+0x1e/0x40 block/ioctl.c:192
#2: 00000000566d4c39 (&type->s_umount_key#50){.+.+}, at: __get_super.part.10+0x1d3/0x280 fs/super.c:663 /* down_read(&sb->s_umount); */
----------------------------------------
When reporting an AB-BA deadlock like shown above, it would be nice if
trace of PID=6541 is printed as well as trace of PID=6540 before calling
panic().
Showing hung tasks up to /proc/sys/kernel/hung_task_warnings could delay
calling panic() but normally there should not be so many hung tasks.
Link: http://lkml.kernel.org/r/201804050705.BHE57833.HVFOFtSOMQJFOL@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Mandeep Singh Baines <msb@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When I was running my testcase which may block hundreds of threads on fs
locks, I got lockup due to output from debug_show_all_locks() added by
commit b2d4c2edb2 ("locking/hung_task: Show all locks").
For example, if 1000 threads were blocked in TASK_UNINTERRUPTIBLE state
and 500 out of 1000 threads hold some lock, debug_show_all_locks() from
for_each_process_thread() loop will report locks held by 500 threads for
1000 times. This is a too much noise.
In order to make sure rcu_lock_break() is called frequently, we should
avoid calling debug_show_all_locks() from for_each_process_thread() loop
because debug_show_all_locks() effectively calls for_each_process_thread()
loop. Let's defer calling debug_show_all_locks() till before panic() or
leaving for_each_process_thread() loop.
Link: http://lkml.kernel.org/r/1489296834-60436-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We are going to split <linux/sched/debug.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/debug.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/signal.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since sysctl_hung_task_warnings == -1 is allowed (infinite warnings),
commit 48a6d64eda ("hung_task: allow hung_task_panic when
hung_task_warnings is 0") should decrement it only when it is not -1.
This prevents the kernel from ceasing warnings after the first
4294967295 ;)
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: John Siddle <jsiddle@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Previously hung_task_panic would not be respected if enabled after
hung_task_warnings had already been decremented to 0.
Permit the kernel to panic if hung_task_panic is enabled after
hung_task_warnings has already been decremented to 0 and another task
hangs for hung_task_timeout_secs seconds.
Check if hung_task_panic is enabled so we don't return prematurely, and
check if hung_task_warnings is non-zero so we don't print the warning
unnecessarily.
[akpm@linux-foundation.org: fix off-by-one]
Link: http://lkml.kernel.org/r/1473450214-4049-1-git-send-email-jsiddle@redhat.com
Signed-off-by: John Siddle <jsiddle@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When we get a hung task it can often be valuable to see _all_ the held
locks on the system (in case we are being blocked on trying to acquire
one), e.g. with this patch we can immediately see where the problem is
below:
INFO: task trinity-c3:14933 blocked for more than 120 seconds.
Not tainted 4.8.0-rc1+ #135
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
trinity-c3 D ffff88010c16fc88 0 14933 1 0x00080004
ffff88010c16fc88 000000003b9aca00 0000000000000000 0000000000000296
00000000776cdf88 ffff88011a520ae0 ffff88011a520b08 ffff88011a520198
ffffffff867d7f00 ffff88011942c080 ffff880116841580 ffff88010c168000
Call Trace:
[<ffffffff845e9d37>] schedule+0x77/0x230
[<ffffffff833cb8b9>] __lock_sock+0x129/0x250
[<ffffffff833cb790>] ? __sk_destruct+0x450/0x450
[<ffffffff81408ac0>] ? wake_bit_function+0x2e0/0x2e0
[<ffffffff833d832b>] lock_sock_nested+0xeb/0x120
[<ffffffff83bad815>] irda_setsockopt+0x65/0xb40
[<ffffffff833c6c09>] SyS_setsockopt+0x139/0x230
[<ffffffff833c6ad0>] ? SyS_recv+0x20/0x20
[<ffffffff81004660>] ? trace_event_raw_event_sys_enter+0xb90/0xb90
[<ffffffff823c7023>] ? __this_cpu_preempt_check+0x13/0x20
[<ffffffff8162ee60>] ? __context_tracking_exit.part.3+0x30/0x1b0
[<ffffffff833c6ad0>] ? SyS_recv+0x20/0x20
[<ffffffff81007bd3>] do_syscall_64+0x1b3/0x4b0
[<ffffffff845f84aa>] entry_SYSCALL64_slow_path+0x25/0x25
Showing all locks held in the system:
2 locks held by khungtaskd/563:
#0: (rcu_read_lock){......}, at: [<ffffffff81534ce6>] watchdog+0x106/0x910
#1: (tasklist_lock){......}, at: [<ffffffff8141b3c4>] debug_show_all_locks+0x74/0x360
1 lock held by trinity-c0/19280:
#0: (sk_lock-AF_IRDA){......}, at: [<ffffffff83bab7c6>] irda_accept+0x176/0x10f0
1 lock held by trinity-c0/12865:
#0: (sk_lock-AF_IRDA){......}, at: [<ffffffff83bab7c6>] irda_accept+0x176/0x10f0
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mandeep Singh Baines <msb@chromium.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1471538460-7505-1-git-send-email-vegard.nossum@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When new timeout is written to /proc/sys/kernel/hung_task_timeout_secs,
khungtaskd is interrupted and again sleeps for full timeout duration.
This means that hang task will not be checked if new timeout is written
periodically within old timeout duration and/or checking of hang task
will be delayed for up to previous timeout duration. Fix this by
remembering last time khungtaskd checked hang task.
This change will allow other watchdog tasks (if any) to share khungtaskd
by sleeping for minimal timeout diff of all watchdog tasks. Doing more
watchdog tasks from khungtaskd will reduce the possibility of printk()
collisions by multiple watchdog threads.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
