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2024-11-11hung_task: add detect count for hung tasksLance Yang
Patch series "add detect count for hung tasks", v2. This patchset adds a counter, hung_task_detect_count, to track the number of times hung tasks are detected. IHMO, hung tasks are a critical metric. Currently, we detect them by periodically parsing dmesg. However, this method isn't as user-friendly as using a counter. Sometimes, a short-lived issue with NIC or hard drive can quickly decrease the hung_task_warnings to zero. Without warnings, we must directly access the node to ensure that there are no more hung tasks and that the system has recovered. After all, load average alone cannot provide a clear picture. Once this counter is in place, in a high-density deployment pattern, we plan to set hung_task_timeout_secs to a lower number to improve stability, even though this might result in false positives. And then we can set a time-based threshold: if hung tasks last beyond this duration, we will automatically migrate containers to other nodes. Based on past experience, this approach could help avoid many production disruptions. Moreover, just like other important events such as OOM that already have counters, having a dedicated counter for hung tasks makes sense ;) This patch (of 2): This commit adds a counter, hung_task_detect_count, to track the number of times hung tasks are detected. IHMO, hung tasks are a critical metric. Currently, we detect them by periodically parsing dmesg. However, this method isn't as user-friendly as using a counter. Sometimes, a short-lived issue with NIC or hard drive can quickly decrease the hung_task_warnings to zero. Without warnings, we must directly access the node to ensure that there are no more hung tasks and that the system has recovered. After all, load average alone cannot provide a clear picture. Once this counter is in place, in a high-density deployment pattern, we plan to set hung_task_timeout_secs to a lower number to improve stability, even though this might result in false positives. And then we can set a time-based threshold: if hung tasks last beyond this duration, we will automatically migrate containers to other nodes. Based on past experience, this approach could help avoid many production disruptions. Moreover, just like other important events such as OOM that already have counters, having a dedicated counter for hung tasks makes sense. [ioworker0@gmail.com: proc_doulongvec_minmax instead of proc_dointvec] Link: https://lkml.kernel.org/r/20241101114833.8377-1-ioworker0@gmail.com Link: https://lkml.kernel.org/r/20241027120747.42833-1-ioworker0@gmail.com Link: https://lkml.kernel.org/r/20241027120747.42833-2-ioworker0@gmail.com Signed-off-by: Mingzhe Yang <mingzhe.yang@ly.com> Signed-off-by: Lance Yang <ioworker0@gmail.com> Cc: Bang Li <libang.li@antgroup.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: David Hildenbrand <david@redhat.com> Cc: Huang Cun <cunhuang@tencent.com> Cc: Joel Granados <j.granados@samsung.com> Cc: Joel Granados <joel.granados@kernel.org> Cc: John Siddle <jsiddle@redhat.com> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Thomas Weißschuh <linux@weissschuh.net> Cc: Yongliang Gao <leonylgao@tencent.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-24sysctl: treewide: constify the ctl_table argument of proc_handlersJoel Granados
const qualify the struct ctl_table argument in the proc_handler function signatures. This is a prerequisite to moving the static ctl_table structs into .rodata data which will ensure that proc_handler function pointers cannot be modified. This patch has been generated by the following coccinelle script: ``` virtual patch @r1@ identifier ctl, write, buffer, lenp, ppos; identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)"; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int write, void *buffer, size_t *lenp, loff_t *ppos); @r2@ identifier func, ctl, write, buffer, lenp, ppos; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int write, void *buffer, size_t *lenp, loff_t *ppos) { ... } @r3@ identifier func; @@ int func( - struct ctl_table * + const struct ctl_table * ,int , void *, size_t *, loff_t *); @r4@ identifier func, ctl; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int , void *, size_t *, loff_t *); @r5@ identifier func, write, buffer, lenp, ppos; @@ int func( - struct ctl_table * + const struct ctl_table * ,int write, void *buffer, size_t *lenp, loff_t *ppos); ``` * Code formatting was adjusted in xfs_sysctl.c to comply with code conventions. The xfs_stats_clear_proc_handler, xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where adjusted. * The ctl_table argument in proc_watchdog_common was const qualified. This is called from a proc_handler itself and is calling back into another proc_handler, making it necessary to change it as part of the proc_handler migration. Co-developed-by: Thomas Weißschuh <linux@weissschuh.net> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Co-developed-by: Joel Granados <j.granados@samsung.com> Signed-off-by: Joel Granados <j.granados@samsung.com>
2024-06-24hung_task: ignore hung_task_warnings when hung_task_panic is enabledYongliang Gao
If hung_task_panic is enabled, don't consider the value of hung_task_warnings and display the information of the hung tasks. In some cases, hung_task_panic might not be initially set up, after several hung tasks occur, the hung_task_warnings count reaches zero. If hung_task_panic is set up later, it may not display any helpful hung task info in dmesg, only showing messages like: Kernel panic - not syncing: hung_task: blocked tasks CPU: 3 PID: 58 Comm: khungtaskd Not tainted 6.10.0-rc3 #19 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) Call Trace: <TASK> panic+0x2f3/0x320 watchdog+0x2dd/0x510 ? __pfx_watchdog+0x10/0x10 kthread+0xe0/0x110 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2f/0x40 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> Link: https://lkml.kernel.org/r/20240613033159.3446265-1-leonylgao@gmail.com Signed-off-by: Yongliang Gao <leonylgao@tencent.com> Reviewed-by: Huang Cun <cunhuang@tencent.com> Cc: Joel Granados <j.granados@samsung.com> Cc: John Siddle <jsiddle@redhat.com> Cc: Kent Overstreet <kent.overstreet@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-24kernel misc: Remove the now superfluous sentinel elements from ctl_table arrayJoel Granados
This commit comes at the tail end of a greater effort to remove the empty elements at the end of the ctl_table arrays (sentinels) which will reduce the overall build time size of the kernel and run time memory bloat by ~64 bytes per sentinel (further information Link : https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/) Remove the sentinel from ctl_table arrays. Reduce by one the values used to compare the size of the adjusted arrays. Signed-off-by: Joel Granados <j.granados@samsung.com>
2024-03-13kernel/hung_task.c: export sysctl_hung_task_timeout_secsKent Overstreet
needed for thread_with_file; also rare but not unheard of to need this in module code, when blocking on user input. one workaround used by some code is wait_event_interruptible() - but that can be buggy if the outer context isn't expecting unwinding. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: fuyuanli <fuyuanli@didiglobal.com>
2023-04-08kernel/hung_task.c: set some hung_task.c variables storage-class-specifier ↵Tom Rix
to static smatch reports several warnings kernel/hung_task.c:31:19: warning: symbol 'sysctl_hung_task_check_count' was not declared. Should it be static? kernel/hung_task.c:50:29: warning: symbol 'sysctl_hung_task_check_interval_secs' was not declared. Should it be static? kernel/hung_task.c:52:19: warning: symbol 'sysctl_hung_task_warnings' was not declared. Should it be static? kernel/hung_task.c:75:28: warning: symbol 'sysctl_hung_task_panic' was not declared. Should it be static? These variables are only used in hung_task.c, so they should be static Link: https://lkml.kernel.org/r/20230312164645.471259-1-trix@redhat.com Signed-off-by: Tom Rix <trix@redhat.com> Cc: Ben Dooks <ben.dooks@sifive.com> Cc: fuyuanli <fuyuanli@didiglobal.com> Cc: John Ogness <john.ogness@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-09hung_task: print message when hung_task_warnings gets down to zero.fuyuanli
It's useful to report it when hung_task_warnings gets down to zero, so that we can know if kernel log was lost or there is no hung task was detected. Link: https://lkml.kernel.org/r/20230201135416.GA6560@didi-ThinkCentre-M920t-N000 Signed-off-by: fuyuanli <fuyuanli@didiglobal.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-09-30sched: Fix more TASK_state comparisonsPeter Zijlstra
Boris reported hung_task splats after commit 5aec788aeb8e ("sched: Fix TASK_state comparisons"). Upon closer consideration of that change it doesn't only exclude TASK_KILLABLE, but also TASK_IDLE. Update the comment to reflect this fact and add an additional TASK_NOLOAD test to exclude them. Additionally, remove the TASK_FREEZABLE early exit from check_hung_task(), a freezable task is not a frozen task. Fixes: 5aec788aeb8e ("sched: Fix TASK_state comparisons") Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Borislav Petkov <bp@alien8.de>
2022-09-28sched: Fix TASK_state comparisonsPeter Zijlstra
Task state is fundamentally a bitmask; direct comparisons are probably not working as intended. Specifically the normal wait-state have a number of possible modifiers: TASK_UNINTERRUPTIBLE: TASK_WAKEKILL, TASK_NOLOAD, TASK_FREEZABLE TASK_INTERRUPTIBLE: TASK_FREEZABLE Specifically, the addition of TASK_FREEZABLE wrecked __wait_is_interruptible(). This however led to an audit of direct comparisons yielding the rest of the changes. Fixes: f5d39b020809 ("freezer,sched: Rewrite core freezer logic") Reported-by: Christian Borntraeger <borntraeger@linux.ibm.com> Debugged-by: Christian Borntraeger <borntraeger@linux.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2022-09-07freezer,sched: Rewrite core freezer logicPeter Zijlstra
Rewrite the core freezer to behave better wrt thawing and be simpler in general. By replacing PF_FROZEN with TASK_FROZEN, a special block state, it is ensured frozen tasks stay frozen until thawed and don't randomly wake up early, as is currently possible. As such, it does away with PF_FROZEN and PF_FREEZER_SKIP, freeing up two PF_flags (yay!). Specifically; the current scheme works a little like: freezer_do_not_count(); schedule(); freezer_count(); And either the task is blocked, or it lands in try_to_freezer() through freezer_count(). Now, when it is blocked, the freezer considers it frozen and continues. However, on thawing, once pm_freezing is cleared, freezer_count() stops working, and any random/spurious wakeup will let a task run before its time. That is, thawing tries to thaw things in explicit order; kernel threads and workqueues before doing bringing SMP back before userspace etc.. However due to the above mentioned races it is entirely possible for userspace tasks to thaw (by accident) before SMP is back. This can be a fatal problem in asymmetric ISA architectures (eg ARMv9) where the userspace task requires a special CPU to run. As said; replace this with a special task state TASK_FROZEN and add the following state transitions: TASK_FREEZABLE -> TASK_FROZEN __TASK_STOPPED -> TASK_FROZEN __TASK_TRACED -> TASK_FROZEN The new TASK_FREEZABLE can be set on any state part of TASK_NORMAL (IOW. TASK_INTERRUPTIBLE and TASK_UNINTERRUPTIBLE) -- any such state is already required to deal with spurious wakeups and the freezer causes one such when thawing the task (since the original state is lost). The special __TASK_{STOPPED,TRACED} states *can* be restored since their canonical state is in ->jobctl. With this, frozen tasks need an explicit TASK_FROZEN wakeup and are free of undue (early / spurious) wakeups. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220822114649.055452969@infradead.org
2022-07-29kernel/hung_task: fix address space of proc_dohung_task_timeout_secsBen Dooks
The proc_dohung_task_timeout_secs() function is incorrectly marked as having a __user buffer as argument 3. However this is not the case and it is casing multiple sparse warnings. Fix the following warnings by removing __user from the argument: kernel/hung_task.c:237:52: warning: incorrect type in argument 3 (different address spaces) kernel/hung_task.c:237:52: expected void * kernel/hung_task.c:237:52: got void [noderef] __user *buffer kernel/hung_task.c:287:35: warning: incorrect type in initializer (incompatible argument 3 (different address spaces)) kernel/hung_task.c:287:35: expected int ( [usertype] *proc_handler )( ... ) kernel/hung_task.c:287:35: got int ( * )( ... ) kernel/hung_task.c:295:35: warning: incorrect type in initializer (incompatible argument 3 (different address spaces)) kernel/hung_task.c:295:35: expected int ( [usertype] *proc_handler )( ... ) kernel/hung_task.c:295:35: got int ( * )( ... ) Link: https://lkml.kernel.org/r/20220714074744.189017-1-ben.dooks@sifive.com Signed-off-by: Ben Dooks <ben.dooks@sifive.com> Cc: <Conor.Dooley@microchip.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-06-23Merge branch 'rework/kthreads' into for-linusPetr Mladek
2022-06-23Revert "printk: add functions to prefer direct printing"Petr Mladek
This reverts commit 2bb2b7b57f81255c13f4395ea911d6bdc70c9fe2. The testing of 5.19 release candidates revealed missing synchronization between early and regular console functionality. It would be possible to start the console kthreads later as a workaround. But it is clear that console lock serialized console drivers between each other. It opens a big area of possible problems that were not considered by people involved in the development and review. printk() is crucial for debugging kernel issues and console output is very important part of it. The number of consoles is huge and a proper review would take some time. As a result it need to be reverted for 5.19. Link: https://lore.kernel.org/r/YrBdjVwBOVgLfHyb@alley Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20220623145157.21938-7-pmladek@suse.com
2022-05-27Merge tag 'mm-nonmm-stable-2022-05-26' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 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 ...
2022-04-29lib/Kconfig.debug: remove more CONFIG_..._VALUE indirectionsRasmus Villemoes
As in "kernel/panic.c: remove CONFIG_PANIC_ON_OOPS_VALUE indirection", use the IS_ENABLED() helper rather than having a hidden config option. Link: https://lkml.kernel.org/r/20220321121301.1389693-1-linux@rasmusvillemoes.dk Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-04-22printk: add functions to prefer direct printingJohn Ogness
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
2022-01-22hung_task: move hung_task sysctl interface to hung_task.cXiaoming Ni
The kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain. To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic. So move hung_task sysctl interface to hung_task.c and use register_sysctl() to register the sysctl interface. [mcgrof@kernel.org: commit log refresh and fixed 2-3 0day reported compile issues] Link: https://lkml.kernel.org/r/20211123202347.818157-4-mcgrof@kernel.org Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Amir Goldstein <amir73il@gmail.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qing Wang <wangqing@vivo.com> Cc: Sebastian Reichel <sre@kernel.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Stephen Kitt <steve@sk2.org> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Antti Palosaari <crope@iki.fi> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Clemens Ladisch <clemens@ladisch.de> Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Julia Lawall <julia.lawall@inria.fr> Cc: Lukas Middendorf <kernel@tuxforce.de> Cc: Mark Fasheh <mark@fasheh.com> Cc: Phillip Potter <phil@philpotter.co.uk> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Douglas Gilbert <dgilbert@interlog.com> Cc: James E.J. Bottomley <jejb@linux.ibm.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: John Ogness <john.ogness@linutronix.de> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-02Merge branch 'akpm' (patches from Andrew)Linus Torvalds
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 ...
2021-07-01kernel.h: split out panic and oops helpersAndy Shevchenko
kernel.h is being used as a dump for all kinds of stuff for a long time. Here is the attempt to start cleaning it up by splitting out panic and oops helpers. There are several purposes of doing this: - dropping dependency in bug.h - dropping a loop by moving out panic_notifier.h - unload kernel.h from something which has its own domain At the same time convert users tree-wide to use new headers, although for the time being include new header back to kernel.h to avoid twisted indirected includes for existing users. [akpm@linux-foundation.org: thread_info.h needs limits.h] [andriy.shevchenko@linux.intel.com: ia64 fix] Link: https://lkml.kernel.org/r/20210520130557.55277-1-andriy.shevchenko@linux.intel.com Link: https://lkml.kernel.org/r/20210511074137.33666-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Co-developed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Corey Minyard <cminyard@mvista.com> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Wei Liu <wei.liu@kernel.org> Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Sebastian Reichel <sre@kernel.org> Acked-by: Luis Chamberlain <mcgrof@kernel.org> Acked-by: Stephen Boyd <sboyd@kernel.org> Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Acked-by: Helge Deller <deller@gmx.de> # parisc Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-18sched: Change task_struct::statePeter Zijlstra
Change the type and name of task_struct::state. Drop the volatile and shrink it to an 'unsigned int'. Rename it in order to find all uses such that we can use READ_ONCE/WRITE_ONCE as appropriate. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Acked-by: Will Deacon <will@kernel.org> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Link: https://lore.kernel.org/r/20210611082838.550736351@infradead.org
2020-11-02kernel/hung_task.c: make type annotations consistentLukas Bulwahn
Commit 32927393dc1c ("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>
2020-06-08kernel/hung_task.c: introduce sysctl to print all traces when a hung task is ↵Guilherme G. Piccoli
detected Commit 401c636a0eeb ("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>
2020-06-08kernel/hung_task convert hung_task_panic boot parameter to sysctlVlastimil Babka
We can now handle sysctl parameters on kernel command line and have infrastructure to convert legacy command line options that duplicate sysctl to become a sysctl alias. This patch converts the hung_task_panic parameter. Note that the sysctl handler is more strict and allows only 0 and 1, while the legacy parameter allowed any non-zero value. But there is little reason anyone would not be using 1. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: David Rientjes <rientjes@google.com> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Guilherme G . Piccoli" <gpiccoli@canonical.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Ivan Teterevkov <ivan.teterevkov@nutanix.com> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20200427180433.7029-4-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-21treewide: Add SPDX license identifier for missed filesThomas Gleixner
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>
2019-03-07kernel/hung_task.c: Use continuously blocked time when reporting.Tetsuo Handa
Since commit a2e514453861 ("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>
2019-03-07kernel/hung_task.c - fix sparse warningsValdis Kletnieks
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>
2019-01-04kernel/hung_task.c: break RCU locks based on jiffiesTetsuo Handa
check_hung_uninterruptible_tasks() is currently calling rcu_lock_break() for every 1024 threads. But check_hung_task() is very slow if printk() was called, and is very fast otherwise. If many threads within some 1024 threads called printk(), the RCU grace period might be extended enough to trigger RCU stall warnings. Therefore, calling rcu_lock_break() for every some fixed jiffies will be safer. Link: http://lkml.kernel.org/r/1544800658-11423-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-04kernel/hung_task.c: force console verbose before panicLiu, Chuansheng
Based on commit 401c636a0eeb ("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>
2018-10-25kernel: hung_task.c: disable on suspendVitaly Kuznetsov
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>
2018-08-22kernel/hung_task.c: allow to set checking interval separately from timeoutDmitry Vyukov
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>
2018-06-07kernel/hung_task.c: show all hung tasks before panicTetsuo Handa
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>
2017-05-08kernel/hung_task.c: defer showing held locksTetsuo Handa
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 <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>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar
<linux/sched/debug.h> 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>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar
<linux/sched/signal.h> 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>
2016-12-12hung_task: decrement sysctl_hung_task_warnings only if it is positiveTetsuo Handa
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 <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>
2016-10-11hung_task: allow hung_task_panic when hung_task_warnings is 0John Siddle
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>
2016-08-24locking/hung_task: Show all locksVegard Nossum
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>
2016-03-22kernel/hung_task.c: use timeout diff when timeout is updatedTetsuo Handa
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>
2015-04-15kernel/hung_task.c: change hung_task.c to use for_each_process_thread()Aaron Tomlin
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 <atomlin@redhat.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Dave Wysochanski <dwysocha@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>
2014-06-04kernel/hung_task.c: convert simple_strtoul to kstrtouintFabian Frederick
sysctl_hung_task_panic has been changed to unsigned int. use kstrtouint instead of obsolete simple_strtoul Signed-off-by: Fabian Frederick <fabf@skynet.be> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-03kernel: audit/fix non-modular users of module_init in core codePaul Gortmaker
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>
2014-01-25hung_task: Display every hung task warningAaron Tomlin
When khungtaskd detects hung tasks, it prints out backtraces from a number of those tasks. Limiting the number of backtraces being printed out can result in the user not seeing the information necessary to debug the issue. The hung_task_warnings sysctl controls this feature. This patch makes it possible for hung_task_warnings to accept a special value to print an unlimited number of backtraces when khungtaskd detects hung tasks. The special value is -1. To use this value it is necessary to change types from ulong to int. Signed-off-by: Aaron Tomlin <atomlin@redhat.com> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Cc: oleg@redhat.com Link: http://lkml.kernel.org/r/1390239253-24030-3-git-send-email-atomlin@redhat.com [ Build warning fix. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-11-15Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds
Pull KVM changes from Paolo Bonzini: "Here are the 3.13 KVM changes. There was a lot of work on the PPC side: the HV and emulation flavors can now coexist in a single kernel is probably the most interesting change from a user point of view. On the x86 side there are nested virtualization improvements and a few bugfixes. ARM got transparent huge page support, improved overcommit, and support for big endian guests. Finally, there is a new interface to connect KVM with VFIO. This helps with devices that use NoSnoop PCI transactions, letting the driver in the guest execute WBINVD instructions. This includes some nVidia cards on Windows, that fail to start without these patches and the corresponding userspace changes" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (146 commits) kvm, vmx: Fix lazy FPU on nested guest arm/arm64: KVM: PSCI: propagate caller endianness to the incoming vcpu arm/arm64: KVM: MMIO support for BE guest kvm, cpuid: Fix sparse warning kvm: Delete prototype for non-existent function kvm_check_iopl kvm: Delete prototype for non-existent function complete_pio hung_task: add method to reset detector pvclock: detect watchdog reset at pvclock read kvm: optimize out smp_mb after srcu_read_unlock srcu: API for barrier after srcu read unlock KVM: remove vm mmap method KVM: IOMMU: hva align mapping page size KVM: x86: trace cpuid emulation when called from emulator KVM: emulator: cleanup decode_register_operand() a bit KVM: emulator: check rex prefix inside decode_register() KVM: x86: fix emulation of "movzbl %bpl, %eax" kvm_host: typo fix KVM: x86: emulate SAHF instruction MAINTAINERS: add tree for kvm.git Documentation/kvm: add a 00-INDEX file ...
2013-11-06hung_task: add method to reset detectorMarcelo Tosatti
In certain occasions it is possible for a hung task detector positive to be false: continuation from a paused VM, for example. Add a method to reset detection, similar as is done with other kernel watchdogs. Acked-by: Don Zickus <dzickus@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-10-31hung_task debugging: Add tracepoint to report the hangOleg Nesterov
Currently check_hung_task() prints a warning if it detects the problem, but it is not convenient to watch the system logs if user-space wants to be notified about the hang. Add the new trace_sched_process_hang() into check_hung_task(), this way a user-space monitor can easily wait for the hang and potentially resolve a problem. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Dave Sullivan <dsulliva@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20131019161828.GA7439@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-23hung_task: Change sysctl_hung_task_check_count to 'int'Li Zefan
As 'sysctl_hung_task_check_count' is 'unsigned long' when this value is assigned to max_count in check_hung_uninterruptible_tasks(), it's truncated to 'int' type. This causes a minor artifact: if we write 2^32 to sysctl.hung_task_check_count, hung task detection will be effectively disabled. With this fix, it will still truncate the user input to 32 bits, but reading sysctl.hung_task_check_count reflects the actual truncated value. Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: Ingo Molnar <mingo@kernel.org> Link: http://lkml.kernel.org/r/523FFF4E.9050401@huawei.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-08-02hung_task debugging: Print more info when reporting the problemOleg Nesterov
printk(KERN_ERR) from check_hung_task() likely means we have a bug, but unlike BUG_ON()/WARN_ON ()it doesn't show the kernel version, this complicates the bug-reports investigation. Add the additional pr_err() to print tainted/release/version like dump_stack_print_info() does, the output becomes: INFO: task perl:504 blocked for more than 2 seconds. Not tainted 3.11.0-rc1-10367-g136bb46-dirty #1763 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. ... While at it, turn the old printk's into pr_err(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: ahecox@redhat.com Cc: Christopher Williams <cww@redhat.com> Cc: dwysocha@redhat.com Cc: gavin@redhat.com Cc: Mandeep Singh Baines <msb@chromium.org> Cc: nshi@redhat.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20130801165941.GA17544@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-04-25hung task debugging: Inject NMI when hung and going to panicSasha Levin
Send an NMI to all CPUs when a hung task is detected and the hung task code is configured to panic. This gives us a fairly uptodate snapshot of all CPUs in the system. This lets us get stack trace of all CPUs which makes life easier trying to debug a deadlock, and the NMI doesn't change anything since the next step is a kernel panic. Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/1331848040-1676-1-git-send-email-levinsasha928@gmail.com [ extended the changelog a bit ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-03-05hung_task: fix the broken rcu_lock_break() logicOleg Nesterov
check_hung_uninterruptible_tasks()->rcu_lock_break() introduced by "softlockup: check all tasks in hung_task" commit ce9dbe24 looks absolutely wrong. - rcu_lock_break() does put_task_struct(). If the task has exited it is not safe to even read its ->state, nothing protects this task_struct. - The TASK_DEAD checks are wrong too. Contrary to the comment, we can't use it to check if the task was unhashed. It can be unhashed without TASK_DEAD, or it can be valid with TASK_DEAD. For example, an autoreaping task can do release_task(current) long before it sets TASK_DEAD in do_exit(). Or, a zombie task can have ->state == TASK_DEAD but release_task() was not called, and in this case we must not break the loop. Change this code to check pid_alive() instead, and do this before we drop the reference to the task_struct. Note: while_each_thread() under rcu_read_lock() is not really safe, it can livelock. This will be fixed later, but fortunately in this case the "max_count" logic saves us anyway. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Mandeep Singh Baines <msb@google.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.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>
2012-01-03hung_task: fix false positive during vforkMandeep Singh Baines
vfork parent uninterruptibly and unkillably waits for its child to exec/exit. This wait is of unbounded length. Ignore such waits in the hung_task detector. Signed-off-by: Mandeep Singh Baines <msb@chromium.org> Reported-by: Sasha Levin <levinsasha928@gmail.com> LKML-Reference: <1325344394.28904.43.camel@lappy> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: John Kacur <jkacur@redhat.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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