user/sven/linux.git/kernel/hung_task.c, branch v4.13.6

kernel/hung_task.c: defer showing held locks

2017-05-09T00:15:10Z

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 b2d4c2edb2e4 ("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 Reviewed-by: Vegard Nossum Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:34Z

We are going to split out of , which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder file that just maps to 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 Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:29Z

hung_task: decrement sysctl_hung_task_warnings only if it is positive

2016-12-13T02:55:09Z

Since sysctl_hung_task_warnings == -1 is allowed (infinite warnings), commit 48a6d64edadb ("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 Cc: John Siddle Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

hung_task: allow hung_task_panic when hung_task_warnings is 0

2016-10-11T22:06:33Z

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 Cc: Tetsuo Handa Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

locking/hung_task: Show all locks

2016-08-24T10:16:13Z

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: [] schedule+0x77/0x230 [] __lock_sock+0x129/0x250 [] ? __sk_destruct+0x450/0x450 [] ? wake_bit_function+0x2e0/0x2e0 [] lock_sock_nested+0xeb/0x120 [] irda_setsockopt+0x65/0xb40 [] SyS_setsockopt+0x139/0x230 [] ? SyS_recv+0x20/0x20 [] ? trace_event_raw_event_sys_enter+0xb90/0xb90 [] ? __this_cpu_preempt_check+0x13/0x20 [] ? __context_tracking_exit.part.3+0x30/0x1b0 [] ? SyS_recv+0x20/0x20 [] do_syscall_64+0x1b3/0x4b0 [] entry_SYSCALL64_slow_path+0x25/0x25 Showing all locks held in the system: 2 locks held by khungtaskd/563: #0: (rcu_read_lock){......}, at: [] watchdog+0x106/0x910 #1: (tasklist_lock){......}, at: [] debug_show_all_locks+0x74/0x360 1 lock held by trinity-c0/19280: #0: (sk_lock-AF_IRDA){......}, at: [] irda_accept+0x176/0x10f0 1 lock held by trinity-c0/12865: #0: (sk_lock-AF_IRDA){......}, at: [] irda_accept+0x176/0x10f0 Signed-off-by: Vegard Nossum Cc: Andrew Morton Cc: Linus Torvalds Cc: Mandeep Singh Baines Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1471538460-7505-1-git-send-email-vegard.nossum@oracle.com Signed-off-by: Ingo Molnar

kernel/hung_task.c: use timeout diff when timeout is updated

2016-03-22T22:36:02Z

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 Cc: Oleg Nesterov Cc: Aaron Tomlin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/hung_task.c: change hung_task.c to use for_each_process_thread()

2015-04-15T23:35:22Z

In check_hung_uninterruptible_tasks() avoid the use of deprecated while_each_thread(). The "max_count" logic will prevent a livelock - see commit 0c740d0a ("introduce for_each_thread() to replace the buggy while_each_thread()"). Having said this let's use for_each_process_thread(). Signed-off-by: Aaron Tomlin Acked-by: Oleg Nesterov Cc: David Rientjes Cc: Dave Wysochanski Cc: Aaron Tomlin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/hung_task.c: convert simple_strtoul to kstrtouint

2014-06-04T23:54:15Z

sysctl_hung_task_panic has been changed to unsigned int. use kstrtouint instead of obsolete simple_strtoul Signed-off-by: Fabian Frederick Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel: audit/fix non-modular users of module_init in core code

2014-04-03T23:21:07Z

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 Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Eric Biederman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds