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* time: Remove CONFIG_TIMER_STATSKees Cook2017-02-101-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently CONFIG_TIMER_STATS exposes process information across namespaces: kernel/time/timer_list.c print_timer(): SEQ_printf(m, ", %s/%d", tmp, timer->start_pid); /proc/timer_list: #11: <0000000000000000>, hrtimer_wakeup, S:01, do_nanosleep, cron/2570 Given that the tracer can give the same information, this patch entirely removes CONFIG_TIMER_STATS. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: John Stultz <john.stultz@linaro.org> Cc: Nicolas Pitre <nicolas.pitre@linaro.org> Cc: linux-doc@vger.kernel.org Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Xing Gao <xgao01@email.wm.edu> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Jessica Frazelle <me@jessfraz.com> Cc: kernel-hardening@lists.openwall.com Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: Michal Marek <mmarek@suse.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Olof Johansson <olof@lixom.net> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-api@vger.kernel.org Cc: Arjan van de Ven <arjan@linux.intel.com> Link: http://lkml.kernel.org/r/20170208192659.GA32582@beast Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* Merge branch 'for-4.9' into for-4.10Tejun Heo2016-10-191-18/+85
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| * workqueue: move wq_numa_init() to workqueue_init()Tejun Heo2016-10-191-2/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While splitting up workqueue initialization into two parts, ac8f73400782 ("workqueue: make workqueue available early during boot") put wq_numa_init() into workqueue_init_early(). Unfortunately, on some archs including power and arm64, cpu to node mapping isn't yet established by the time the early init is called leading to incorrect NUMA initialization and subsequently the following oops due to zero cpumask on node-specific unbound pools. Unable to handle kernel paging request for data at address 0x00000038 Faulting instruction address: 0xc0000000000fc0cc Oops: Kernel access of bad area, sig: 11 [#1] SMP NR_CPUS=2048 NUMA PowerNV Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.8.0-compiler_gcc-6.2.0-next-20161005 #94 task: c0000007f5400000 task.stack: c000001ffc084000 NIP: c0000000000fc0cc LR: c0000000000ed928 CTR: c0000000000fbfd0 REGS: c000001ffc087780 TRAP: 0300 Not tainted (4.8.0-compiler_gcc-6.2.0-next-20161005) MSR: 9000000002009033 <SF,HV,VEC,EE,ME,IR,DR,RI,LE> CR: 48000424 XER: 00000000 CFAR: c0000000000089dc DAR: 0000000000000038 DSISR: 40000000 SOFTE: 0 GPR00: c0000000000ed928 c000001ffc087a00 c000000000e63200 c000000010d6d600 GPR04: c0000007f5409200 0000000000000021 000000000748e08c 000000000000001f GPR08: 0000000000000000 0000000000000021 000000000748f1f8 0000000000000000 GPR12: 0000000028000422 c00000000fb80000 c00000000000e0c8 0000000000000000 GPR16: 0000000000000000 0000000000000000 0000000000000021 0000000000000001 GPR20: ffffffffafb50401 0000000000000000 c000000010d6d600 000000000000ba7e GPR24: 000000000000ba7e c000000000d8bc58 afb504000afb5041 0000000000000001 GPR28: 0000000000000000 0000000000000004 c0000007f5409280 0000000000000000 NIP [c0000000000fc0cc] enqueue_task_fair+0xfc/0x18b0 LR [c0000000000ed928] activate_task+0x78/0xe0 Call Trace: [c000001ffc087a00] [c0000007f5409200] 0xc0000007f5409200 (unreliable) [c000001ffc087b10] [c0000000000ed928] activate_task+0x78/0xe0 [c000001ffc087b50] [c0000000000ede58] ttwu_do_activate+0x68/0xc0 [c000001ffc087b90] [c0000000000ef1b8] try_to_wake_up+0x208/0x4f0 [c000001ffc087c10] [c0000000000d3484] create_worker+0x144/0x250 [c000001ffc087cb0] [c000000000cd72d0] workqueue_init+0x124/0x150 [c000001ffc087d00] [c000000000cc0e74] kernel_init_freeable+0x158/0x360 [c000001ffc087dc0] [c00000000000e0e4] kernel_init+0x24/0x160 [c000001ffc087e30] [c00000000000bfa0] ret_from_kernel_thread+0x5c/0xbc Instruction dump: 62940401 3b800000 3aa00000 7f17c378 3a600001 3b600001 60000000 60000000 60420000 72490021 ebfe0150 2f890001 <ebbf0038> 419e0de0 7fbee840 419e0e58 ---[ end trace 0000000000000000 ]--- Fix it by moving wq_numa_init() to workqueue_init(). As this means that the early intialization may not have full NUMA info for per-cpu pools and ignores NUMA affinity for unbound pools, fix them up from workqueue_init() after wq_numa_init(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Michael Ellerman <mpe@ellerman.id.au> Link: http://lkml.kernel.org/r/87twck5wqo.fsf@concordia.ellerman.id.au Fixes: ac8f73400782 ("workqueue: make workqueue available early during boot") Signed-off-by: Tejun Heo <tj@kernel.org>
| * workqueue: remove keventd_up()Tejun Heo2016-09-171-1/+1
| | | | | | | | | | | | | | keventd_up() no longer has in-kernel users. Remove it and make wq_online static. Signed-off-by: Tejun Heo <tj@kernel.org>
| * workqueue: make workqueue available early during bootTejun Heo2016-09-171-16/+60
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Workqueue is currently initialized in an early init call; however, there are cases where early boot code has to be split and reordered to come after workqueue initialization or the same code path which makes use of workqueues is used both before workqueue initailization and after. The latter cases have to gate workqueue usages with keventd_up() tests, which is nasty and easy to get wrong. Workqueue usages have become widespread and it'd be a lot more convenient if it can be used very early from boot. This patch splits workqueue initialization into two steps. workqueue_init_early() which sets up the basic data structures so that workqueues can be created and work items queued, and workqueue_init() which actually brings up workqueues online and starts executing queued work items. The former step can be done very early during boot once memory allocation, cpumasks and idr are initialized. The latter right after kthreads become available. This allows work item queueing and canceling from very early boot which is what most of these use cases want. * As systemd_wq being initialized doesn't indicate that workqueue is fully online anymore, update keventd_up() to test wq_online instead. The follow-up patches will get rid of all its usages and the function itself. * Flushing doesn't make sense before workqueue is fully initialized. The flush functions trigger WARN and return immediately before fully online. * Work items are never in-flight before fully online. Canceling can always succeed by skipping the flush step. * Some code paths can no longer assume to be called with irq enabled as irq is disabled during early boot. Use irqsave/restore operations instead. v2: Watchdog init, which requires timer to be running, moved from workqueue_init_early() to workqueue_init(). Signed-off-by: Tejun Heo <tj@kernel.org> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/CA+55aFx0vPuMuxn00rBSM192n-Du5uxy+4AvKa0SBSOVJeuCGg@mail.gmail.com
| * workqueue: dump workqueue state on sanity check failures in destroy_workqueue()Tejun Heo2016-09-161-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | destroy_workqueue() performs a number of sanity checks to ensure that the workqueue is empty before proceeding with destruction. However, it's not always easy to tell what's going on just from the warning message. Let's dump workqueue state after sanity check failures to help debugging. Signed-off-by: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/CACT4Y+Zs6vkjHo9qHb4TrEiz3S4+quvvVQ9VWvj2Mx6pETGb9Q@mail.gmail.com Cc: Dmitry Vyukov <dvyukov@google.com>
* | kthread: rename probe_kthread_data() to kthread_probe_data()Petr Mladek2016-10-111-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "kthread: Kthread worker API improvements" The intention of this patchset is to make it easier to manipulate and maintain kthreads. Especially, I want to replace all the custom main cycles with a generic one. Also I want to make the kthreads sleep in a consistent state in a common place when there is no work. This patch (of 11): A good practice is to prefix the names of functions by the name of the subsystem. This patch fixes the name of probe_kthread_data(). The other wrong functions names are part of the kthread worker API and will be fixed separately. Link: http://lkml.kernel.org/r/1470754545-17632-2-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Suggested-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Tejun Heo <tj@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Borislav Petkov <bp@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | workqueue: add cancel_work()Jens Axboe2016-08-291-14/+26
|/ | | | | | | | Like cancel_delayed_work(), but for regular work. Signed-off-by: Jens Axboe <axboe@fb.com> Mehed-by: Tejun Heo <tj@kernel.org> Acked-by: Tejun Heo <tj@kernel.org>
* Merge branch 'smp-hotplug-for-linus' of ↵Linus Torvalds2016-07-291-65/+43
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull smp hotplug updates from Thomas Gleixner: "This is the next part of the hotplug rework. - Convert all notifiers with a priority assigned - Convert all CPU_STARTING/DYING notifiers The final removal of the STARTING/DYING infrastructure will happen when the merge window closes. Another 700 hundred line of unpenetrable maze gone :)" * 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (70 commits) timers/core: Correct callback order during CPU hot plug leds/trigger/cpu: Move from CPU_STARTING to ONLINE level powerpc/numa: Convert to hotplug state machine arm/perf: Fix hotplug state machine conversion irqchip/armada: Avoid unused function warnings ARC/time: Convert to hotplug state machine clocksource/atlas7: Convert to hotplug state machine clocksource/armada-370-xp: Convert to hotplug state machine clocksource/exynos_mct: Convert to hotplug state machine clocksource/arm_global_timer: Convert to hotplug state machine rcu: Convert rcutree to hotplug state machine KVM/arm/arm64/vgic-new: Convert to hotplug state machine smp/cfd: Convert core to hotplug state machine x86/x2apic: Convert to CPU hotplug state machine profile: Convert to hotplug state machine timers/core: Convert to hotplug state machine hrtimer: Convert to hotplug state machine x86/tboot: Convert to hotplug state machine arm64/armv8 deprecated: Convert to hotplug state machine hwtracing/coresight-etm4x: Convert to hotplug state machine ...
| * workqueue: Convert to state machine callbacksThomas Gleixner2016-07-141-65/+43
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Get rid of the prio ordering of the separate notifiers and use a proper state callback pair. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153335.197083890@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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*-. | Merge branches 'pm-sleep' and 'pm-tools'Rafael J. Wysocki2016-07-251-2/+2
|\ \| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * pm-sleep: PM / hibernate: Introduce test_resume mode for hibernation x86 / hibernate: Use hlt_play_dead() when resuming from hibernation PM / hibernate: Image data protection during restoration PM / hibernate: Add missing braces in __register_nosave_region() PM / hibernate: Clean up comments in snapshot.c PM / hibernate: Clean up function headers in snapshot.c PM / hibernate: Add missing braces in hibernate_setup() PM / hibernate: Recycle safe pages after image restoration PM / hibernate: Simplify mark_unsafe_pages() PM / hibernate: Do not free preallocated safe pages during image restore PM / suspend: show workqueue state in suspend flow PM / sleep: make PM notifiers called symmetrically PM / sleep: Make pm_prepare_console() return void PM / Hibernate: Don't let kasan instrument snapshot.c * pm-tools: PM / tools: scripts: AnalyzeSuspend v4.2 tools/turbostat: allow user to alter DESTDIR and PREFIX
| * | PM / suspend: show workqueue state in suspend flowRoger Lu2016-07-021-2/+2
| |/ | | | | | | | | | | | | | | | | If freezable workqueue aborts suspend flow, show workqueue state for debug purpose. Signed-off-by: Roger Lu <roger.lu@mediatek.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* / workqueue: Fix setting affinity of unbound worker threadsPeter Zijlstra2016-06-161-5/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With commit e9d867a67fd03ccc ("sched: Allow per-cpu kernel threads to run on online && !active"), __set_cpus_allowed_ptr() expects that only strict per-cpu kernel threads can have affinity to an online CPU which is not yet active. This assumption is currently broken in the CPU_ONLINE notification handler for the workqueues where restore_unbound_workers_cpumask() calls set_cpus_allowed_ptr() when the first cpu in the unbound worker's pool->attr->cpumask comes online. Since set_cpus_allowed_ptr() is called with pool->attr->cpumask in which only one CPU is online which is not yet active, we get the following WARN_ON during an CPU online operation. ------------[ cut here ]------------ WARNING: CPU: 40 PID: 248 at kernel/sched/core.c:1166 __set_cpus_allowed_ptr+0x228/0x2e0 Modules linked in: CPU: 40 PID: 248 Comm: cpuhp/40 Not tainted 4.6.0-autotest+ #4 <..snip..> Call Trace: [c000000f273ff920] [c00000000010493c] __set_cpus_allowed_ptr+0x2cc/0x2e0 (unreliable) [c000000f273ffac0] [c0000000000ed4b0] workqueue_cpu_up_callback+0x2c0/0x470 [c000000f273ffb70] [c0000000000f5c58] notifier_call_chain+0x98/0x100 [c000000f273ffbc0] [c0000000000c5ed0] __cpu_notify+0x70/0xe0 [c000000f273ffc00] [c0000000000c6028] notify_online+0x38/0x50 [c000000f273ffc30] [c0000000000c5214] cpuhp_invoke_callback+0x84/0x250 [c000000f273ffc90] [c0000000000c562c] cpuhp_up_callbacks+0x5c/0x120 [c000000f273ffce0] [c0000000000c64d4] cpuhp_thread_fun+0x184/0x1c0 [c000000f273ffd20] [c0000000000fa050] smpboot_thread_fn+0x290/0x2a0 [c000000f273ffd80] [c0000000000f45b0] kthread+0x110/0x130 [c000000f273ffe30] [c000000000009570] ret_from_kernel_thread+0x5c/0x6c ---[ end trace 00f1456578b2a3b2 ]--- This patch fixes this by limiting the mask to the intersection of the pool affinity and online CPUs. Changelog-cribbed-from: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Reported-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Tejun Heo <tj@kernel.org>
* debugobjects: insulate non-fixup logic related to static obj from fixup ↵Du, Changbin2016-05-191-34/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | callbacks When activating a static object we need make sure that the object is tracked in the object tracker. If it is a non-static object then the activation is illegal. In previous implementation, each subsystem need take care of this in their fixup callbacks. Actually we can put it into debugobjects core. Thus we can save duplicated code, and have *pure* fixup callbacks. To achieve this, a new callback "is_static_object" is introduced to let the type specific code decide whether a object is static or not. If yes, we take it into object tracker, otherwise give warning and invoke fixup callback. This change has paassed debugobjects selftest, and I also do some test with all debugobjects supports enabled. At last, I have a concern about the fixups that can it change the object which is in incorrect state on fixup? Because the 'addr' may not point to any valid object if a non-static object is not tracked. Then Change such object can overwrite someone's memory and cause unexpected behaviour. For example, the timer_fixup_activate bind timer to function stub_timer. Link: http://lkml.kernel.org/r/1462576157-14539-1-git-send-email-changbin.du@intel.com [changbin.du@intel.com: improve code comments where invoke the new is_static_object callback] Link: http://lkml.kernel.org/r/1462777431-8171-1-git-send-email-changbin.du@intel.com Signed-off-by: Du, Changbin <changbin.du@intel.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Triplett <josh@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tejun Heo <tj@kernel.org> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* workqueue: update debugobjects fixup callbacks return typeDu, Changbin2016-05-191-10/+10
| | | | | | | | | | | | | | | Update the return type to use bool instead of int, corresponding to change (debugobjects: make fixup functions return bool instead of int) Signed-off-by: Du, Changbin <changbin.du@intel.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Triplett <josh@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tejun Heo <tj@kernel.org> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-4.6-fixes' of ↵Linus Torvalds2016-05-131-0/+11
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq Pull workqueue fix from Tejun Heo: "CPU hotplug callbacks can invoke DOWN_FAILED w/o preceding DOWN_PREPARE which can trigger a WARN_ON() in workqueue. The bug has been there for a very long time. It only triggers if CPU down fails at a specific point and I don't think it has adverse effects other than the warning messages. The fix is very low impact" * 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: fix rebind bound workers warning
| * workqueue: fix rebind bound workers warningWanpeng Li2016-05-121-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ------------[ cut here ]------------ WARNING: CPU: 0 PID: 16 at kernel/workqueue.c:4559 rebind_workers+0x1c0/0x1d0 Modules linked in: CPU: 0 PID: 16 Comm: cpuhp/0 Not tainted 4.6.0-rc4+ #31 Hardware name: IBM IBM System x3550 M4 Server -[7914IUW]-/00Y8603, BIOS -[D7E128FUS-1.40]- 07/23/2013 0000000000000000 ffff881037babb58 ffffffff8139d885 0000000000000010 0000000000000000 0000000000000000 0000000000000000 ffff881037babba8 ffffffff8108505d ffff881037ba0000 000011cf3e7d6e60 0000000000000046 Call Trace: dump_stack+0x89/0xd4 __warn+0xfd/0x120 warn_slowpath_null+0x1d/0x20 rebind_workers+0x1c0/0x1d0 workqueue_cpu_up_callback+0xf5/0x1d0 notifier_call_chain+0x64/0x90 ? trace_hardirqs_on_caller+0xf2/0x220 ? notify_prepare+0x80/0x80 __raw_notifier_call_chain+0xe/0x10 __cpu_notify+0x35/0x50 notify_down_prepare+0x5e/0x80 ? notify_prepare+0x80/0x80 cpuhp_invoke_callback+0x73/0x330 ? __schedule+0x33e/0x8a0 cpuhp_down_callbacks+0x51/0xc0 cpuhp_thread_fun+0xc1/0xf0 smpboot_thread_fn+0x159/0x2a0 ? smpboot_create_threads+0x80/0x80 kthread+0xef/0x110 ? wait_for_completion+0xf0/0x120 ? schedule_tail+0x35/0xf0 ret_from_fork+0x22/0x50 ? __init_kthread_worker+0x70/0x70 ---[ end trace eb12ae47d2382d8f ]--- notify_down_prepare: attempt to take down CPU 0 failed This bug can be reproduced by below config w/ nohz_full= all cpus: CONFIG_BOOTPARAM_HOTPLUG_CPU0=y CONFIG_DEBUG_HOTPLUG_CPU0=y CONFIG_NO_HZ_FULL=y As Thomas pointed out: | If a down prepare callback fails, then DOWN_FAILED is invoked for all | callbacks which have successfully executed DOWN_PREPARE. | | But, workqueue has actually two notifiers. One which handles | UP/DOWN_FAILED/ONLINE and one which handles DOWN_PREPARE. | | Now look at the priorities of those callbacks: | | CPU_PRI_WORKQUEUE_UP = 5 | CPU_PRI_WORKQUEUE_DOWN = -5 | | So the call order on DOWN_PREPARE is: | | CB 1 | CB ... | CB workqueue_up() -> Ignores DOWN_PREPARE | CB ... | CB X ---> Fails | | So we call up to CB X with DOWN_FAILED | | CB 1 | CB ... | CB workqueue_up() -> Handles DOWN_FAILED | CB ... | CB X-1 | | So the problem is that the workqueue stuff handles DOWN_FAILED in the up | callback, while it should do it in the down callback. Which is not a good idea | either because it wants to be called early on rollback... | | Brilliant stuff, isn't it? The hotplug rework will solve this problem because | the callbacks become symetric, but for the existing mess, we need some | workaround in the workqueue code. The boot CPU handles housekeeping duty(unbound timers, workqueues, timekeeping, ...) on behalf of full dynticks CPUs. It must remain online when nohz full is enabled. There is a priority set to every notifier_blocks: workqueue_cpu_up > tick_nohz_cpu_down > workqueue_cpu_down So tick_nohz_cpu_down callback failed when down prepare cpu 0, and notifier_blocks behind tick_nohz_cpu_down will not be called any more, which leads to workers are actually not unbound. Then hotplug state machine will fallback to undo and online cpu 0 again. Workers will be rebound unconditionally even if they are not unbound and trigger the warning in this progress. This patch fix it by catching !DISASSOCIATED to avoid rebind bound workers. Cc: Tejun Heo <tj@kernel.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Frédéric Weisbecker <fweisbec@gmail.com> Cc: stable@vger.kernel.org Suggested-by: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
* | Merge branch 'for-4.6-fixes' of ↵Linus Torvalds2016-04-271-0/+29
|\| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq Pull workqueue fix from Tejun Heo: "So, it turns out we had a silly bug in the most fundamental part of workqueue for a very long time. AFAICS, this dates back to pre-git era and has quite likely been there from the time workqueue was first introduced. A work item uses its PENDING bit to synchronize multiple queuers. Anyone who wins the PENDING bit owns the pending state of the work item. Whether a queuer wins or loses the race, one thing should be guaranteed - there will soon be at least one execution of the work item - where "after" means that the execution instance would be able to see all the changes that the queuer has made prior to the queueing attempt. Unfortunately, we were missing a smp_mb() after clearing PENDING for execution, so nothing guaranteed visibility of the changes that a queueing loser has made, which manifested as a reproducible blk-mq stall. Lots of kudos to Roman for debugging the problem. The patch for -stable is the minimal one. For v3.7, Peter is working on a patch to make the code path slightly more efficient and less fragile" * 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: fix ghost PENDING flag while doing MQ IO
| * workqueue: fix ghost PENDING flag while doing MQ IORoman Pen2016-04-261-0/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The bug in a workqueue leads to a stalled IO request in MQ ctx->rq_list with the following backtrace: [ 601.347452] INFO: task kworker/u129:5:1636 blocked for more than 120 seconds. [ 601.347574] Tainted: G O 4.4.5-1-storage+ #6 [ 601.347651] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 601.348142] kworker/u129:5 D ffff880803077988 0 1636 2 0x00000000 [ 601.348519] Workqueue: ibnbd_server_fileio_wq ibnbd_dev_file_submit_io_worker [ibnbd_server] [ 601.348999] ffff880803077988 ffff88080466b900 ffff8808033f9c80 ffff880803078000 [ 601.349662] ffff880807c95000 7fffffffffffffff ffffffff815b0920 ffff880803077ad0 [ 601.350333] ffff8808030779a0 ffffffff815b01d5 0000000000000000 ffff880803077a38 [ 601.350965] Call Trace: [ 601.351203] [<ffffffff815b0920>] ? bit_wait+0x60/0x60 [ 601.351444] [<ffffffff815b01d5>] schedule+0x35/0x80 [ 601.351709] [<ffffffff815b2dd2>] schedule_timeout+0x192/0x230 [ 601.351958] [<ffffffff812d43f7>] ? blk_flush_plug_list+0xc7/0x220 [ 601.352208] [<ffffffff810bd737>] ? ktime_get+0x37/0xa0 [ 601.352446] [<ffffffff815b0920>] ? bit_wait+0x60/0x60 [ 601.352688] [<ffffffff815af784>] io_schedule_timeout+0xa4/0x110 [ 601.352951] [<ffffffff815b3a4e>] ? _raw_spin_unlock_irqrestore+0xe/0x10 [ 601.353196] [<ffffffff815b093b>] bit_wait_io+0x1b/0x70 [ 601.353440] [<ffffffff815b056d>] __wait_on_bit+0x5d/0x90 [ 601.353689] [<ffffffff81127bd0>] wait_on_page_bit+0xc0/0xd0 [ 601.353958] [<ffffffff81096db0>] ? autoremove_wake_function+0x40/0x40 [ 601.354200] [<ffffffff81127cc4>] __filemap_fdatawait_range+0xe4/0x140 [ 601.354441] [<ffffffff81127d34>] filemap_fdatawait_range+0x14/0x30 [ 601.354688] [<ffffffff81129a9f>] filemap_write_and_wait_range+0x3f/0x70 [ 601.354932] [<ffffffff811ced3b>] blkdev_fsync+0x1b/0x50 [ 601.355193] [<ffffffff811c82d9>] vfs_fsync_range+0x49/0xa0 [ 601.355432] [<ffffffff811cf45a>] blkdev_write_iter+0xca/0x100 [ 601.355679] [<ffffffff81197b1a>] __vfs_write+0xaa/0xe0 [ 601.355925] [<ffffffff81198379>] vfs_write+0xa9/0x1a0 [ 601.356164] [<ffffffff811c59d8>] kernel_write+0x38/0x50 The underlying device is a null_blk, with default parameters: queue_mode = MQ submit_queues = 1 Verification that nullb0 has something inflight: root@pserver8:~# cat /sys/block/nullb0/inflight 0 1 root@pserver8:~# find /sys/block/nullb0/mq/0/cpu* -name rq_list -print -exec cat {} \; ... /sys/block/nullb0/mq/0/cpu2/rq_list CTX pending: ffff8838038e2400 ... During debug it became clear that stalled request is always inserted in the rq_list from the following path: save_stack_trace_tsk + 34 blk_mq_insert_requests + 231 blk_mq_flush_plug_list + 281 blk_flush_plug_list + 199 wait_on_page_bit + 192 __filemap_fdatawait_range + 228 filemap_fdatawait_range + 20 filemap_write_and_wait_range + 63 blkdev_fsync + 27 vfs_fsync_range + 73 blkdev_write_iter + 202 __vfs_write + 170 vfs_write + 169 kernel_write + 56 So blk_flush_plug_list() was called with from_schedule == true. If from_schedule is true, that means that finally blk_mq_insert_requests() offloads execution of __blk_mq_run_hw_queue() and uses kblockd workqueue, i.e. it calls kblockd_schedule_delayed_work_on(). That means, that we race with another CPU, which is about to execute __blk_mq_run_hw_queue() work. Further debugging shows the following traces from different CPUs: CPU#0 CPU#1 ---------------------------------- ------------------------------- reqeust A inserted STORE hctx->ctx_map[0] bit marked kblockd_schedule...() returns 1 <schedule to kblockd workqueue> request B inserted STORE hctx->ctx_map[1] bit marked kblockd_schedule...() returns 0 *** WORK PENDING bit is cleared *** flush_busy_ctxs() is executed, but bit 1, set by CPU#1, is not observed As a result request B pended forever. This behaviour can be explained by speculative LOAD of hctx->ctx_map on CPU#0, which is reordered with clear of PENDING bit and executed _before_ actual STORE of bit 1 on CPU#1. The proper fix is an explicit full barrier <mfence>, which guarantees that clear of PENDING bit is to be executed before all possible speculative LOADS or STORES inside actual work function. Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com> Cc: Gioh Kim <gi-oh.kim@profitbricks.com> Cc: Michael Wang <yun.wang@profitbricks.com> Cc: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-block@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Tejun Heo <tj@kernel.org>
* | Merge branch 'for-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wqLinus Torvalds2016-03-181-5/+4
|\ \ | |/ |/| | | | | | | | | | | | | | | Pull workqueue updates from Tejun Heo: "Three trivial workqueue changes" * 'for-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: Fix comment for work_on_cpu() sched/core: Get rid of 'cpu' argument in wq_worker_sleeping() workqueue: Replace usage of init_name with dev_set_name()
| * workqueue: Fix comment for work_on_cpu()Anna-Maria Gleixner2016-03-111-1/+1
| | | | | | | | | | | | | | | | | | | | | | Function is processed in thread context, not in user context. Cc: Tejun Heo <tj@kernel.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Signed-off-by: Tejun Heo <tj@kernel.org>
| * sched/core: Get rid of 'cpu' argument in wq_worker_sleeping()Alexander Gordeev2016-03-021-3/+2
| | | | | | | | | | | | | | | | | | | | | | | | Given that wq_worker_sleeping() could only be called for a CPU it is running on, we do not need passing a CPU ID as an argument. Suggested-by: Oleg Nesterov <oleg@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Alexander Gordeev <agordeev@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
| * workqueue: Replace usage of init_name with dev_set_name()Lars-Peter Clausen2016-02-171-1/+1
| | | | | | | | | | | | | | | | | | | | The init_name property of the device struct is sort of a hack and should only be used for statically allocated devices. Since the device is dynamically allocated here it is safe to use the proper way to set a devices name by calling dev_set_name(). Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Tejun Heo <tj@kernel.org>
* | tags: Fix DEFINE_PER_CPU expansionsPeter Zijlstra2016-03-151-2/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ make tags GEN tags ctags: Warning: drivers/acpi/processor_idle.c:64: null expansion of name pattern "\1" ctags: Warning: drivers/xen/events/events_2l.c:41: null expansion of name pattern "\1" ctags: Warning: kernel/locking/lockdep.c:151: null expansion of name pattern "\1" ctags: Warning: kernel/rcu/rcutorture.c:133: null expansion of name pattern "\1" ctags: Warning: kernel/rcu/rcutorture.c:135: null expansion of name pattern "\1" ctags: Warning: kernel/workqueue.c:323: null expansion of name pattern "\1" ctags: Warning: net/ipv4/syncookies.c:53: null expansion of name pattern "\1" ctags: Warning: net/ipv6/syncookies.c:44: null expansion of name pattern "\1" ctags: Warning: net/rds/page.c:45: null expansion of name pattern "\1" Which are all the result of the DEFINE_PER_CPU pattern: scripts/tags.sh:200: '/\<DEFINE_PER_CPU([^,]*, *\([[:alnum:]_]*\)/\1/v/' scripts/tags.sh:201: '/\<DEFINE_PER_CPU_SHARED_ALIGNED([^,]*, *\([[:alnum:]_]*\)/\1/v/' The below cures them. All except the workqueue one are within reasonable distance of the 80 char limit. TJ do you have any preference on how to fix the wq one, or shall we just not care its too long? Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Tejun Heo <tj@kernel.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* workqueue: handle NUMA_NO_NODE for unbound pool_workqueue lookupTejun Heo2016-02-101-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When looking up the pool_workqueue to use for an unbound workqueue, workqueue assumes that the target CPU is always bound to a valid NUMA node. However, currently, when a CPU goes offline, the mapping is destroyed and cpu_to_node() returns NUMA_NO_NODE. This has always been broken but hasn't triggered often enough before 874bbfe600a6 ("workqueue: make sure delayed work run in local cpu"). After the commit, workqueue forcifully assigns the local CPU for delayed work items without explicit target CPU to fix a different issue. This widens the window where CPU can go offline while a delayed work item is pending causing delayed work items dispatched with target CPU set to an already offlined CPU. The resulting NUMA_NO_NODE mapping makes workqueue try to queue the work item on a NULL pool_workqueue and thus crash. While 874bbfe600a6 has been reverted for a different reason making the bug less visible again, it can still happen. Fix it by mapping NUMA_NO_NODE to the default pool_workqueue from unbound_pwq_by_node(). This is a temporary workaround. The long term solution is keeping CPU -> NODE mapping stable across CPU off/online cycles which is being worked on. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Rafael J. Wysocki <rafael@kernel.org> Cc: Len Brown <len.brown@intel.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/g/1454424264.11183.46.camel@gmail.com Link: http://lkml.kernel.org/g/1453702100-2597-1-git-send-email-tangchen@cn.fujitsu.com
* workqueue: implement "workqueue.debug_force_rr_cpu" debug featureTejun Heo2016-02-091-2/+21
| | | | | | | | | | | | | | | | | Workqueue used to guarantee local execution for work items queued without explicit target CPU. The guarantee is gone now which can break some usages in subtle ways. To flush out those cases, this patch implements a debug feature which forces round-robin CPU selection for all such work items. The debug feature defaults to off and can be enabled with a kernel parameter. The default can be flipped with a debug config option. If you hit this commit during bisection, please refer to 041bd12e272c ("Revert "workqueue: make sure delayed work run in local cpu"") for more information and ping me. Signed-off-by: Tejun Heo <tj@kernel.org>
* workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUsMike Galbraith2016-02-091-2/+32
| | | | | | | | | | | | | | | WORK_CPU_UNBOUND work items queued to a bound workqueue always run locally. This is a good thing normally, but not when the user has asked us to keep unbound work away from certain CPUs. Round robin these to wq_unbound_cpumask CPUs instead, as perturbation avoidance trumps performance. tj: Cosmetic and comment changes. WARN_ON_ONCE() dropped from empty (wq_unbound_cpumask AND cpu_online_mask). If we want that, it should be done when config changes. Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* Revert "workqueue: make sure delayed work run in local cpu"Tejun Heo2016-02-091-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This reverts commit 874bbfe600a660cba9c776b3957b1ce393151b76. Workqueue used to implicity guarantee that work items queued without explicit CPU specified are put on the local CPU. Recent changes in timer broke the guarantee and led to vmstat breakage which was fixed by 176bed1de5bf ("vmstat: explicitly schedule per-cpu work on the CPU we need it to run on"). vmstat is the most likely to expose the issue and it's quite possible that there are other similar problems which are a lot more difficult to trigger. As a preventive measure, 874bbfe600a6 ("workqueue: make sure delayed work run in local cpu") was applied to restore the local CPU guarnatee. Unfortunately, the change exposed a bug in timer code which got fixed by 22b886dd1018 ("timers: Use proper base migration in add_timer_on()"). Due to code restructuring, the commit couldn't be backported beyond certain point and stable kernels which only had 874bbfe600a6 started crashing. The local CPU guarantee was accidental more than anything else and we want to get rid of it anyway. As, with the vmstat case fixed, 874bbfe600a6 is causing more problems than it's fixing, it has been decided to take the chance and officially break the guarantee by reverting the commit. A debug feature will be added to force foreign CPU assignment to expose cases relying on the guarantee and fixes for the individual cases will be backported to stable as necessary. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: 874bbfe600a6 ("workqueue: make sure delayed work run in local cpu") Link: http://lkml.kernel.org/g/20160120211926.GJ10810@quack.suse.cz Cc: stable@vger.kernel.org Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br> Cc: Daniel Bilik <daniel.bilik@neosystem.cz> Cc: Jan Kara <jack@suse.cz> Cc: Shaohua Li <shli@fb.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Ben Hutchings <ben@decadent.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Daniel Bilik <daniel.bilik@neosystem.cz> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Michal Hocko <mhocko@kernel.org>
* workqueue: skip flush dependency checks for legacy workqueuesTejun Heo2016-01-291-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | fca839c00a12 ("workqueue: warn if memory reclaim tries to flush !WQ_MEM_RECLAIM workqueue") implemented flush dependency warning which triggers if a PF_MEMALLOC task or WQ_MEM_RECLAIM workqueue tries to flush a !WQ_MEM_RECLAIM workquee. This assumes that workqueues marked with WQ_MEM_RECLAIM sit in memory reclaim path and making it depend on something which may need more memory to make forward progress can lead to deadlocks. Unfortunately, workqueues created with the legacy create*_workqueue() interface always have WQ_MEM_RECLAIM regardless of whether they are depended upon memory reclaim or not. These spurious WQ_MEM_RECLAIM markings cause spurious triggering of the flush dependency checks. WARNING: CPU: 0 PID: 6 at kernel/workqueue.c:2361 check_flush_dependency+0x138/0x144() workqueue: WQ_MEM_RECLAIM deferwq:deferred_probe_work_func is flushing !WQ_MEM_RECLAIM events:lru_add_drain_per_cpu ... Workqueue: deferwq deferred_probe_work_func [<c0017acc>] (unwind_backtrace) from [<c0013134>] (show_stack+0x10/0x14) [<c0013134>] (show_stack) from [<c0245f18>] (dump_stack+0x94/0xd4) [<c0245f18>] (dump_stack) from [<c0026f9c>] (warn_slowpath_common+0x80/0xb0) [<c0026f9c>] (warn_slowpath_common) from [<c0026ffc>] (warn_slowpath_fmt+0x30/0x40) [<c0026ffc>] (warn_slowpath_fmt) from [<c00390b8>] (check_flush_dependency+0x138/0x144) [<c00390b8>] (check_flush_dependency) from [<c0039ca0>] (flush_work+0x50/0x15c) [<c0039ca0>] (flush_work) from [<c00c51b0>] (lru_add_drain_all+0x130/0x180) [<c00c51b0>] (lru_add_drain_all) from [<c00f728c>] (migrate_prep+0x8/0x10) [<c00f728c>] (migrate_prep) from [<c00bfbc4>] (alloc_contig_range+0xd8/0x338) [<c00bfbc4>] (alloc_contig_range) from [<c00f8f18>] (cma_alloc+0xe0/0x1ac) [<c00f8f18>] (cma_alloc) from [<c001cac4>] (__alloc_from_contiguous+0x38/0xd8) [<c001cac4>] (__alloc_from_contiguous) from [<c001ceb4>] (__dma_alloc+0x240/0x278) [<c001ceb4>] (__dma_alloc) from [<c001cf78>] (arm_dma_alloc+0x54/0x5c) [<c001cf78>] (arm_dma_alloc) from [<c0355ea4>] (dmam_alloc_coherent+0xc0/0xec) [<c0355ea4>] (dmam_alloc_coherent) from [<c039cc4c>] (ahci_port_start+0x150/0x1dc) [<c039cc4c>] (ahci_port_start) from [<c0384734>] (ata_host_start.part.3+0xc8/0x1c8) [<c0384734>] (ata_host_start.part.3) from [<c03898dc>] (ata_host_activate+0x50/0x148) [<c03898dc>] (ata_host_activate) from [<c039d558>] (ahci_host_activate+0x44/0x114) [<c039d558>] (ahci_host_activate) from [<c039f05c>] (ahci_platform_init_host+0x1d8/0x3c8) [<c039f05c>] (ahci_platform_init_host) from [<c039e6bc>] (tegra_ahci_probe+0x448/0x4e8) [<c039e6bc>] (tegra_ahci_probe) from [<c0347058>] (platform_drv_probe+0x50/0xac) [<c0347058>] (platform_drv_probe) from [<c03458cc>] (driver_probe_device+0x214/0x2c0) [<c03458cc>] (driver_probe_device) from [<c0343cc0>] (bus_for_each_drv+0x60/0x94) [<c0343cc0>] (bus_for_each_drv) from [<c03455d8>] (__device_attach+0xb0/0x114) [<c03455d8>] (__device_attach) from [<c0344ab8>] (bus_probe_device+0x84/0x8c) [<c0344ab8>] (bus_probe_device) from [<c0344f48>] (deferred_probe_work_func+0x68/0x98) [<c0344f48>] (deferred_probe_work_func) from [<c003b738>] (process_one_work+0x120/0x3f8) [<c003b738>] (process_one_work) from [<c003ba48>] (worker_thread+0x38/0x55c) [<c003ba48>] (worker_thread) from [<c0040f14>] (kthread+0xdc/0xf4) [<c0040f14>] (kthread) from [<c000f778>] (ret_from_fork+0x14/0x3c) Fix it by marking workqueues created via create*_workqueue() with __WQ_LEGACY and disabling flush dependency checks on them. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Thierry Reding <thierry.reding@gmail.com> Link: http://lkml.kernel.org/g/20160126173843.GA11115@ulmo.nvidia.com Fixes: fca839c00a12 ("workqueue: warn if memory reclaim tries to flush !WQ_MEM_RECLAIM workqueue")
* workqueue: simplify the apply_workqueue_attrs_locked()wanghaibin2016-01-071-7/+4
| | | | | | | | | | | If the apply_wqattrs_prepare() returns NULL, it has already cleaned up the related resources, so it can return directly and avoid calling the clean up function again. This doesn't introduce any functional changes. Signed-off-by: wanghaibin <wanghaibin.wang@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* workqueue: implement lockup detectorTejun Heo2015-12-081-3/+171
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Workqueue stalls can happen from a variety of usage bugs such as missing WQ_MEM_RECLAIM flag or concurrency managed work item indefinitely staying RUNNING. These stalls can be extremely difficult to hunt down because the usual warning mechanisms can't detect workqueue stalls and the internal state is pretty opaque. To alleviate the situation, this patch implements workqueue lockup detector. It periodically monitors all worker_pools periodically and, if any pool failed to make forward progress longer than the threshold duration, triggers warning and dumps workqueue state as follows. BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 31s! Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=17/256 pending: monkey_wrench_fn, e1000_watchdog, cache_reap, vmstat_shepherd, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, cgroup_release_agent workqueue events_power_efficient: flags=0x80 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256 pending: check_lifetime, neigh_periodic_work workqueue cgroup_pidlist_destroy: flags=0x0 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/1 pending: cgroup_pidlist_destroy_work_fn ... The detection mechanism is controller through kernel parameter workqueue.watchdog_thresh and can be updated at runtime through the sysfs module parameter file. v2: Decoupled from softlockup control knobs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Don Zickus <dzickus@redhat.com> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Chris Mason <clm@fb.com> Cc: Andrew Morton <akpm@linux-foundation.org>
* workqueue: warn if memory reclaim tries to flush !WQ_MEM_RECLAIM workqueueTejun Heo2015-12-081-0/+35
| | | | | | | | | Task or work item involved in memory reclaim trying to flush a non-WQ_MEM_RECLAIM workqueue or one of its work items can lead to deadlock. Trigger WARN_ONCE() if such conditions are detected. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org>
* Merge branch 'for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wqLinus Torvalds2015-11-051-12/+14
|\ | | | | | | | | | | | | | | | | | | | | Pull workqueue update from Tejun Heo: "This pull request contains one patch to make an unbound worker pool allocated from the NUMA node containing it if such node exists. As unbound worker pools are node-affine by default, this makes most pools allocated on the right node" * 'for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: Allocate the unbound pool using local node memory
| * workqueue: Allocate the unbound pool using local node memoryXunlei Pang2015-10-121-12/+14
| | | | | | | | | | | | | | | | | | | | | | | | Currently, get_unbound_pool() uses kzalloc() to allocate the worker pool. Actually, we can use the right node to do the allocation, achieving local memory access. This patch selects target node first, and uses kzalloc_node() instead. Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: make sure delayed work run in local cpuShaohua Li2015-09-301-4/+4
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | My system keeps crashing with below message. vmstat_update() schedules a delayed work in current cpu and expects the work runs in the cpu. schedule_delayed_work() is expected to make delayed work run in local cpu. The problem is timer can be migrated with NO_HZ. __queue_work() queues work in timer handler, which could run in a different cpu other than where the delayed work is scheduled. The end result is the delayed work runs in different cpu. The patch makes __queue_delayed_work records local cpu earlier. Where the timer runs doesn't change where the work runs with the change. [ 28.010131] ------------[ cut here ]------------ [ 28.010609] kernel BUG at ../mm/vmstat.c:1392! [ 28.011099] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC KASAN [ 28.011860] Modules linked in: [ 28.012245] CPU: 0 PID: 289 Comm: kworker/0:3 Tainted: G W4.3.0-rc3+ #634 [ 28.013065] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140709_153802- 04/01/2014 [ 28.014160] Workqueue: events vmstat_update [ 28.014571] task: ffff880117682580 ti: ffff8800ba428000 task.ti: ffff8800ba428000 [ 28.015445] RIP: 0010:[<ffffffff8115f921>] [<ffffffff8115f921>]vmstat_update+0x31/0x80 [ 28.016282] RSP: 0018:ffff8800ba42fd80 EFLAGS: 00010297 [ 28.016812] RAX: 0000000000000000 RBX: ffff88011a858dc0 RCX:0000000000000000 [ 28.017585] RDX: ffff880117682580 RSI: ffffffff81f14d8c RDI:ffffffff81f4df8d [ 28.018366] RBP: ffff8800ba42fd90 R08: 0000000000000001 R09:0000000000000000 [ 28.019169] R10: 0000000000000000 R11: 0000000000000121 R12:ffff8800baa9f640 [ 28.019947] R13: ffff88011a81e340 R14: ffff88011a823700 R15:0000000000000000 [ 28.020071] FS: 0000000000000000(0000) GS:ffff88011a800000(0000)knlGS:0000000000000000 [ 28.020071] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 28.020071] CR2: 00007ff6144b01d0 CR3: 00000000b8e93000 CR4:00000000000006f0 [ 28.020071] Stack: [ 28.020071] ffff88011a858dc0 ffff8800baa9f640 ffff8800ba42fe00ffffffff8106bd88 [ 28.020071] ffffffff8106bd0b 0000000000000096 0000000000000000ffffffff82f9b1e8 [ 28.020071] ffffffff829f0b10 0000000000000000 ffffffff81f18460ffff88011a81e340 [ 28.020071] Call Trace: [ 28.020071] [<ffffffff8106bd88>] process_one_work+0x1c8/0x540 [ 28.020071] [<ffffffff8106bd0b>] ? process_one_work+0x14b/0x540 [ 28.020071] [<ffffffff8106c214>] worker_thread+0x114/0x460 [ 28.020071] [<ffffffff8106c100>] ? process_one_work+0x540/0x540 [ 28.020071] [<ffffffff81071bf8>] kthread+0xf8/0x110 [ 28.020071] [<ffffffff81071b00>] ?kthread_create_on_node+0x200/0x200 [ 28.020071] [<ffffffff81a6522f>] ret_from_fork+0x3f/0x70 [ 28.020071] [<ffffffff81071b00>] ?kthread_create_on_node+0x200/0x200 Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: stable@vger.kernel.org # v2.6.31+
* Merge branch 'for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wqLinus Torvalds2015-09-021-1/+1
|\ | | | | | | | | | | | | | | | | | | | | Pull workqueue updates from Tejun Heo: "Only three trivial changes for workqueue this time - doc, MAINTAINERS and EXPORT_SYMBOL updates" * 'for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: fix some docbook warnings workqueue: Make flush_workqueue() available again to non GPL modules workqueue: add myself as a dedicated reviwer
| * workqueue: Make flush_workqueue() available again to non GPL modulesTim Gardner2015-08-041-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 37b1ef31a568fc02e53587620226e5f3c66454c8 ("workqueue: move flush_scheduled_work() to workqueue.h") moved the exported non GPL flush_scheduled_work() from a function to an inline wrapper. Unfortunately, it directly calls flush_workqueue() which is a GPL function. This has the effect of changing the licensing requirement for this function and makes it unavailable to non GPL modules. See commit ad7b1f841f8a54c6d61ff181451f55b68175e15a ("workqueue: Make schedule_work() available again to non GPL modules") for precedent. Signed-off-by: Tim Gardner <tim.gardner@canonical.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | Merge branch 'sched-core-for-linus' of ↵Linus Torvalds2015-08-311-4/+2
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: "The biggest change in this cycle is the rewrite of the main SMP load balancing metric: the CPU load/utilization. The main goal was to make the metric more precise and more representative - see the changelog of this commit for the gory details: 9d89c257dfb9 ("sched/fair: Rewrite runnable load and utilization average tracking") It is done in a way that significantly reduces complexity of the code: 5 files changed, 249 insertions(+), 494 deletions(-) and the performance testing results are encouraging. Nevertheless we need to keep an eye on potential regressions, since this potentially affects every SMP workload in existence. This work comes from Yuyang Du. Other changes: - SCHED_DL updates. (Andrea Parri) - Simplify architecture callbacks by removing finish_arch_switch(). (Peter Zijlstra et al) - cputime accounting: guarantee stime + utime == rtime. (Peter Zijlstra) - optimize idle CPU wakeups some more - inspired by Facebook server loads. (Mike Galbraith) - stop_machine fixes and updates. (Oleg Nesterov) - Introduce the 'trace_sched_waking' tracepoint. (Peter Zijlstra) - sched/numa tweaks. (Srikar Dronamraju) - misc fixes and small cleanups" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits) sched/deadline: Fix comment in enqueue_task_dl() sched/deadline: Fix comment in push_dl_tasks() sched: Change the sched_class::set_cpus_allowed() calling context sched: Make sched_class::set_cpus_allowed() unconditional sched: Fix a race between __kthread_bind() and sched_setaffinity() sched: Ensure a task has a non-normalized vruntime when returning back to CFS sched/numa: Fix NUMA_DIRECT topology identification tile: Reorganize _switch_to() sched, sparc32: Update scheduler comments in copy_thread() sched: Remove finish_arch_switch() sched, tile: Remove finish_arch_switch sched, sh: Fold finish_arch_switch() into switch_to() sched, score: Remove finish_arch_switch() sched, avr32: Remove finish_arch_switch() sched, MIPS: Get rid of finish_arch_switch() sched, arm: Remove finish_arch_switch() sched/fair: Clean up load average references sched/fair: Provide runnable_load_avg back to cfs_rq sched/fair: Remove task and group entity load when they are dead sched/fair: Init cfs_rq's sched_entity load average ...
| * | sched: Fix a race between __kthread_bind() and sched_setaffinity()Peter Zijlstra2015-08-121-4/+2
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Because sched_setscheduler() checks p->flags & PF_NO_SETAFFINITY without locks, a caller might observe an old value and race with the set_cpus_allowed_ptr() call from __kthread_bind() and effectively undo it: __kthread_bind() do_set_cpus_allowed() <SYSCALL> sched_setaffinity() if (p->flags & PF_NO_SETAFFINITIY) set_cpus_allowed_ptr() p->flags |= PF_NO_SETAFFINITY Fix the bug by putting everything under the regular scheduler locks. This also closes a hole in the serialization of task_struct::{nr_,}cpus_allowed. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Tejun Heo <tj@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dedekind1@gmail.com Cc: juri.lelli@arm.com Cc: mgorman@suse.de Cc: riel@redhat.com Cc: rostedt@goodmis.org Link: http://lkml.kernel.org/r/20150515154833.545640346@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* / rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()Paul E. McKenney2015-07-221-10/+10
|/ | | | | | | | | | This commit renames rcu_lockdep_assert() to RCU_LOCKDEP_WARN() for consistency with the WARN() series of macros. This also requires inverting the sense of the conditional, which this commit also does. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Ingo Molnar <mingo@kernel.org>
* Merge tag 'modules-next-for-linus' of ↵Linus Torvalds2015-07-011-6/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux Pull module updates from Rusty Russell: "Main excitement here is Peter Zijlstra's lockless rbtree optimization to speed module address lookup. He found some abusers of the module lock doing that too. A little bit of parameter work here too; including Dan Streetman's breaking up the big param mutex so writing a parameter can load another module (yeah, really). Unfortunately that broke the usual suspects, !CONFIG_MODULES and !CONFIG_SYSFS, so those fixes were appended too" * tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (26 commits) modules: only use mod->param_lock if CONFIG_MODULES param: fix module param locks when !CONFIG_SYSFS. rcu: merge fix for Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() module: add per-module param_lock module: make perm const params: suppress unused variable error, warn once just in case code changes. modules: clarify CONFIG_MODULE_COMPRESS help, suggest 'N'. kernel/module.c: avoid ifdefs for sig_enforce declaration kernel/workqueue.c: remove ifdefs over wq_power_efficient kernel/params.c: export param_ops_bool_enable_only kernel/params.c: generalize bool_enable_only kernel/module.c: use generic module param operaters for sig_enforce kernel/params: constify struct kernel_param_ops uses sysfs: tightened sysfs permission checks module: Rework module_addr_{min,max} module: Use __module_address() for module_address_lookup() module: Make the mod_tree stuff conditional on PERF_EVENTS || TRACING module: Optimize __module_address() using a latched RB-tree rbtree: Implement generic latch_tree seqlock: Introduce raw_read_seqcount_latch() ...
| * kernel/workqueue.c: remove ifdefs over wq_power_efficientLuis R. Rodriguez2015-05-281-6/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We can avoid an ifdef over wq_power_efficient's declaration by just using IS_ENABLED(). Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Kees Cook <keescook@chromium.org> Cc: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: linux-kernel@vger.kernel.org Cc: cocci@systeme.lip6.fr Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
* | workqueue: fix typos in commentsShailendra Verma2015-05-291-4/+4
| | | | | | | | | | | | | | | | | | tj: dropped iff -> if, iff is if and only if not a typo. Spotted by Randy Dunlap. Signed-off-by: Shailendra Verma <shailendra.capricorn@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org>
* | workqueue: move flush_scheduled_work() to workqueue.hLai Jiangshan2015-05-211-30/+0
| | | | | | | | | | | | | | flush_scheduled_work() is just a simple call to flush_work(). Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: remove the lock from wq_sysfs_prep_attrs()Lai Jiangshan2015-05-211-2/+2
| | | | | | | | | | | | | | | | | | Reading to wq->unbound_attrs requires protection of either wq_pool_mutex or wq->mutex, and wq_sysfs_prep_attrs() is called with wq_pool_mutex held, so we don't need to grab wq->mutex here. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: remove the declaration of copy_workqueue_attrs()Lai Jiangshan2015-05-211-2/+0
| | | | | | | | | | | | | | | | This pre-declaration was unneeded since a previous refactor patch 6ba94429c8e7 ("workqueue: Reorder sysfs code"). Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: ensure attrs changes are properly synchronizedLai Jiangshan2015-05-191-9/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Current modification to attrs via sysfs is not fully synchronized. Process A (change cpumask) | Process B (change numa affinity) wq_cpumask_store() | wq_sysfs_prep_attrs() | | apply_workqueue_attrs() apply_workqueue_attrs() | It results that the Process B's operation is totally reverted without any notification, it is a buggy behavior. So this patch moves wq_sysfs_prep_attrs() into the protection under wq_pool_mutex to ensure attrs changes are properly synchronized. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: separate out and refactor the locking of applying attrsLai Jiangshan2015-05-191-33/+45
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Applying attrs requires two locks: get_online_cpus() and wq_pool_mutex, and this code is duplicated at two places (apply_workqueue_attrs() and workqueue_set_unbound_cpumask()). So we separate out this locking code into apply_wqattrs_[un]lock() and do a minor refactor on apply_workqueue_attrs(). The apply_wqattrs_[un]lock() will be also used on later patch for ensuring attrs changes are properly synchronized. tj: minor updates to comments Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: simplify wq_update_unbound_numa()Lai Jiangshan2015-05-181-15/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | wq_update_unbound_numa() is known be called with wq_pool_mutex held. But wq_update_unbound_numa() requests wq->mutex before reading wq->unbound_attrs, wq->numa_pwq_tbl[] and wq->dfl_pwq. But these fields were changed to be allowed being read with wq_pool_mutex held. So we simply remove the mutex_lock(&wq->mutex). Without the dependence on the the mutex_lock(&wq->mutex), the test of wq->unbound_attrs->no_numa can also be moved upward. The old code need a long comment to describe the stableness of @wq->unbound_attrs which is also guaranteed by wq_pool_mutex now, so we don't need this such comment. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: wq_pool_mutex protects the attrs-installationLai Jiangshan2015-05-181-7/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Current wq_pool_mutex doesn't proctect the attrs-installation, it results that ->unbound_attrs, ->numa_pwq_tbl[] and ->dfl_pwq can only be accessed under wq->mutex and causes some inconveniences. Example, wq_update_unbound_numa() has to acquire wq->mutex before fetching the wq->unbound_attrs->no_numa and the old_pwq. attrs-installation is a short operation, so this change will no cause any latency for other operations which also acquire the wq_pool_mutex. The only unprotected attrs-installation code is in apply_workqueue_attrs(), so this patch touches code less than comments. It is also a preparation patch for next several patches which read wq->unbound_attrs, wq->numa_pwq_tbl[] and wq->dfl_pwq with only wq_pool_mutex held. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
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