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2021-11-17workqueue: make sysfs of unbound kworker cpumask more cleverMenglong Dong
[ Upstream commit d25302e46592c97d29f70ccb1be558df31a9a360 ] Some unfriendly component, such as dpdk, write the same mask to unbound kworker cpumask again and again. Every time it write to this interface some work is queue to cpu, even though the mask is same with the original mask. So, fix it by return success and do nothing if the cpumask is equal with the old one. Signed-off-by: Mengen Sun <mengensun@tencent.com> Signed-off-by: Menglong Dong <imagedong@tencent.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-09-22workqueue: Fix possible memory leaks in wq_numa_init()Zhen Lei
[ Upstream commit f728c4a9e8405caae69d4bc1232c54ff57b5d20f ] In error handling branch "if (WARN_ON(node == NUMA_NO_NODE))", the previously allocated memories are not released. Doing this before allocating memory eliminates memory leaks. tj: Note that the condition only occurs when the arch code is pretty broken and the WARN_ON might as well be BUG_ON(). Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-07-31workqueue: fix UAF in pwq_unbound_release_workfn()Yang Yingliang
commit b42b0bddcbc87b4c66f6497f66fc72d52b712aa7 upstream. I got a UAF report when doing fuzz test: [ 152.880091][ T8030] ================================================================== [ 152.881240][ T8030] BUG: KASAN: use-after-free in pwq_unbound_release_workfn+0x50/0x190 [ 152.882442][ T8030] Read of size 4 at addr ffff88810d31bd00 by task kworker/3:2/8030 [ 152.883578][ T8030] [ 152.883932][ T8030] CPU: 3 PID: 8030 Comm: kworker/3:2 Not tainted 5.13.0+ #249 [ 152.885014][ T8030] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 [ 152.886442][ T8030] Workqueue: events pwq_unbound_release_workfn [ 152.887358][ T8030] Call Trace: [ 152.887837][ T8030] dump_stack_lvl+0x75/0x9b [ 152.888525][ T8030] ? pwq_unbound_release_workfn+0x50/0x190 [ 152.889371][ T8030] print_address_description.constprop.10+0x48/0x70 [ 152.890326][ T8030] ? pwq_unbound_release_workfn+0x50/0x190 [ 152.891163][ T8030] ? pwq_unbound_release_workfn+0x50/0x190 [ 152.891999][ T8030] kasan_report.cold.15+0x82/0xdb [ 152.892740][ T8030] ? pwq_unbound_release_workfn+0x50/0x190 [ 152.893594][ T8030] __asan_load4+0x69/0x90 [ 152.894243][ T8030] pwq_unbound_release_workfn+0x50/0x190 [ 152.895057][ T8030] process_one_work+0x47b/0x890 [ 152.895778][ T8030] worker_thread+0x5c/0x790 [ 152.896439][ T8030] ? process_one_work+0x890/0x890 [ 152.897163][ T8030] kthread+0x223/0x250 [ 152.897747][ T8030] ? set_kthread_struct+0xb0/0xb0 [ 152.898471][ T8030] ret_from_fork+0x1f/0x30 [ 152.899114][ T8030] [ 152.899446][ T8030] Allocated by task 8884: [ 152.900084][ T8030] kasan_save_stack+0x21/0x50 [ 152.900769][ T8030] __kasan_kmalloc+0x88/0xb0 [ 152.901416][ T8030] __kmalloc+0x29c/0x460 [ 152.902014][ T8030] alloc_workqueue+0x111/0x8e0 [ 152.902690][ T8030] __btrfs_alloc_workqueue+0x11e/0x2a0 [ 152.903459][ T8030] btrfs_alloc_workqueue+0x6d/0x1d0 [ 152.904198][ T8030] scrub_workers_get+0x1e8/0x490 [ 152.904929][ T8030] btrfs_scrub_dev+0x1b9/0x9c0 [ 152.905599][ T8030] btrfs_ioctl+0x122c/0x4e50 [ 152.906247][ T8030] __x64_sys_ioctl+0x137/0x190 [ 152.906916][ T8030] do_syscall_64+0x34/0xb0 [ 152.907535][ T8030] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 152.908365][ T8030] [ 152.908688][ T8030] Freed by task 8884: [ 152.909243][ T8030] kasan_save_stack+0x21/0x50 [ 152.909893][ T8030] kasan_set_track+0x20/0x30 [ 152.910541][ T8030] kasan_set_free_info+0x24/0x40 [ 152.911265][ T8030] __kasan_slab_free+0xf7/0x140 [ 152.911964][ T8030] kfree+0x9e/0x3d0 [ 152.912501][ T8030] alloc_workqueue+0x7d7/0x8e0 [ 152.913182][ T8030] __btrfs_alloc_workqueue+0x11e/0x2a0 [ 152.913949][ T8030] btrfs_alloc_workqueue+0x6d/0x1d0 [ 152.914703][ T8030] scrub_workers_get+0x1e8/0x490 [ 152.915402][ T8030] btrfs_scrub_dev+0x1b9/0x9c0 [ 152.916077][ T8030] btrfs_ioctl+0x122c/0x4e50 [ 152.916729][ T8030] __x64_sys_ioctl+0x137/0x190 [ 152.917414][ T8030] do_syscall_64+0x34/0xb0 [ 152.918034][ T8030] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 152.918872][ T8030] [ 152.919203][ T8030] The buggy address belongs to the object at ffff88810d31bc00 [ 152.919203][ T8030] which belongs to the cache kmalloc-512 of size 512 [ 152.921155][ T8030] The buggy address is located 256 bytes inside of [ 152.921155][ T8030] 512-byte region [ffff88810d31bc00, ffff88810d31be00) [ 152.922993][ T8030] The buggy address belongs to the page: [ 152.923800][ T8030] page:ffffea000434c600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10d318 [ 152.925249][ T8030] head:ffffea000434c600 order:2 compound_mapcount:0 compound_pincount:0 [ 152.926399][ T8030] flags: 0x57ff00000010200(slab|head|node=1|zone=2|lastcpupid=0x7ff) [ 152.927515][ T8030] raw: 057ff00000010200 dead000000000100 dead000000000122 ffff888009c42c80 [ 152.928716][ T8030] raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 [ 152.929890][ T8030] page dumped because: kasan: bad access detected [ 152.930759][ T8030] [ 152.931076][ T8030] Memory state around the buggy address: [ 152.931851][ T8030] ffff88810d31bc00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 152.932967][ T8030] ffff88810d31bc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 152.934068][ T8030] >ffff88810d31bd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 152.935189][ T8030] ^ [ 152.935763][ T8030] ffff88810d31bd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 152.936847][ T8030] ffff88810d31be00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 152.937940][ T8030] ================================================================== If apply_wqattrs_prepare() fails in alloc_workqueue(), it will call put_pwq() which invoke a work queue to call pwq_unbound_release_workfn() and use the 'wq'. The 'wq' allocated in alloc_workqueue() will be freed in error path when apply_wqattrs_prepare() fails. So it will lead a UAF. CPU0 CPU1 alloc_workqueue() alloc_and_link_pwqs() apply_wqattrs_prepare() fails apply_wqattrs_cleanup() schedule_work(&pwq->unbound_release_work) kfree(wq) worker_thread() pwq_unbound_release_workfn() <- trigger uaf here If apply_wqattrs_prepare() fails, the new pwq are not linked, it doesn't hold any reference to the 'wq', 'wq' is invalid to access in the worker, so add check pwq if linked to fix this. Fixes: 2d5f0764b526 ("workqueue: split apply_workqueue_attrs() into 3 stages") Cc: stable@vger.kernel.org # v4.2+ Reported-by: Hulk Robot <hulkci@huawei.com> Suggested-by: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com> Tested-by: Pavel Skripkin <paskripkin@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-06-16wq: handle VM suspension in stall detectionSergey Senozhatsky
[ Upstream commit 940d71c6462e8151c78f28e4919aa8882ff2054e ] If VCPU is suspended (VM suspend) in wq_watchdog_timer_fn() then once this VCPU resumes it will see the new jiffies value, while it may take a while before IRQ detects PVCLOCK_GUEST_STOPPED on this VCPU and updates all the watchdogs via pvclock_touch_watchdogs(). There is a small chance of misreported WQ stalls in the meantime, because new jiffies is time_after() old 'ts + thresh'. wq_watchdog_timer_fn() { for_each_pool(pool, pi) { if (time_after(jiffies, ts + thresh)) { pr_emerg("BUG: workqueue lockup - pool"); } } } Save jiffies at the beginning of this function and use that value for stall detection. If VM gets suspended then we continue using "old" jiffies value and old WQ touch timestamps. If IRQ at some point restarts the stall detection cycle (pvclock_touch_watchdogs()) then old jiffies will always be before new 'ts + thresh'. Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-04-14workqueue: Move the position of debug_work_activate() in __queue_work()Zqiang
[ Upstream commit 0687c66b5f666b5ad433f4e94251590d9bc9d10e ] The debug_work_activate() is called on the premise that the work can be inserted, because if wq be in WQ_DRAINING status, insert work may be failed. Fixes: e41e704bc4f4 ("workqueue: improve destroy_workqueue() debuggability") Signed-off-by: Zqiang <qiang.zhang@windriver.com> Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-02-07workqueue: Restrict affinity change to rescuerPeter Zijlstra
[ Upstream commit 640f17c82460e9724fd256f0a1f5d99e7ff0bda4 ] create_worker() will already set the right affinity using kthread_bind_mask(), this means only the rescuer will need to change it's affinity. Howveer, while in cpu-hot-unplug a regular task is not allowed to run on online&&!active as it would be pushed away quite agressively. We need KTHREAD_IS_PER_CPU to survive in that environment. Therefore set the affinity after getting that magic flag. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Tested-by: Valentin Schneider <valentin.schneider@arm.com> Link: https://lkml.kernel.org/r/20210121103506.826629830@infradead.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-12workqueue: Kick a worker based on the actual activation of delayed worksYunfeng Ye
[ Upstream commit 01341fbd0d8d4e717fc1231cdffe00343088ce0b ] In realtime scenario, We do not want to have interference on the isolated cpu cores. but when invoking alloc_workqueue() for percpu wq on the housekeeping cpu, it kick a kworker on the isolated cpu. alloc_workqueue pwq_adjust_max_active wake_up_worker The comment in pwq_adjust_max_active() said: "Need to kick a worker after thawed or an unbound wq's max_active is bumped" So it is unnecessary to kick a kworker for percpu's wq when invoking alloc_workqueue(). this patch only kick a worker based on the actual activation of delayed works. Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com> Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-01workqueue: Remove the warning in wq_worker_sleeping()Sebastian Andrzej Siewior
[ Upstream commit 62849a9612924a655c67cf6962920544aa5c20db ] The kernel test robot triggered a warning with the following race: task-ctx A interrupt-ctx B worker -> process_one_work() -> work_item() -> schedule(); -> sched_submit_work() -> wq_worker_sleeping() -> ->sleeping = 1 atomic_dec_and_test(nr_running) __schedule(); *interrupt* async_page_fault() -> local_irq_enable(); -> schedule(); -> sched_submit_work() -> wq_worker_sleeping() -> if (WARN_ON(->sleeping)) return -> __schedule() -> sched_update_worker() -> wq_worker_running() -> atomic_inc(nr_running); -> ->sleeping = 0; -> sched_update_worker() -> wq_worker_running() if (!->sleeping) return In this context the warning is pointless everything is fine. An interrupt before wq_worker_sleeping() will perform the ->sleeping assignment (0 -> 1 > 0) twice. An interrupt after wq_worker_sleeping() will trigger the warning and nr_running will be decremented (by A) and incremented once (only by B, A will skip it). This is the case until the ->sleeping is zeroed again in wq_worker_running(). Remove the WARN statement because this condition may happen. Document that preemption around wq_worker_sleeping() needs to be disabled to protect ->sleeping and not just as an optimisation. Fixes: 6d25be5782e48 ("sched/core, workqueues: Distangle worker accounting from rq lock") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Tejun Heo <tj@kernel.org> Link: https://lkml.kernel.org/r/20200327074308.GY11705@shao2-debian Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-03-18workqueue: don't use wq_select_unbound_cpu() for bound worksHillf Danton
commit aa202f1f56960c60e7befaa0f49c72b8fa11b0a8 upstream. wq_select_unbound_cpu() is designed for unbound workqueues only, but it's wrongly called when using a bound workqueue too. Fixing this ensures work queued to a bound workqueue with cpu=WORK_CPU_UNBOUND always runs on the local CPU. Before, that would happen only if wq_unbound_cpumask happened to include it (likely almost always the case), or was empty, or we got lucky with forced round-robin placement. So restricting /sys/devices/virtual/workqueue/cpumask to a small subset of a machine's CPUs would cause some bound work items to run unexpectedly there. Fixes: ef557180447f ("workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUs") Cc: stable@vger.kernel.org # v4.5+ Signed-off-by: Hillf Danton <hdanton@sina.com> [dj: massage changelog] Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Tejun Heo <tj@kernel.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: linux-kernel@vger.kernel.org Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-01-26workqueue: Add RCU annotation for pwq list walkSebastian Andrzej Siewior
[ Upstream commit 49e9d1a9faf2f71fdfd80a30697ee9a15070626d ] An additional check has been recently added to ensure that a RCU related lock is held while the RCU list is iterated. The `pwqs' are sometimes iterated without a RCU lock but with the &wq->mutex acquired leading to a warning. Teach list_for_each_entry_rcu() that the RCU usage is okay if &wq->mutex is acquired during the list traversal. Fixes: 28875945ba98d ("rcu: Add support for consolidated-RCU reader checking") Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-12-17workqueue: Fix missing kfree(rescuer) in destroy_workqueue()Tejun Heo
commit 8efe1223d73c218ce7e8b2e0e9aadb974b582d7f upstream. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Qian Cai <cai@lca.pw> Fixes: def98c84b6cd ("workqueue: Fix spurious sanity check failures in destroy_workqueue()") Cc: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-12-17workqueue: Fix pwq ref leak in rescuer_thread()Tejun Heo
commit e66b39af00f426b3356b96433d620cb3367ba1ff upstream. 008847f66c3 ("workqueue: allow rescuer thread to do more work.") made the rescuer worker requeue the pwq immediately if there may be more work items which need rescuing instead of waiting for the next mayday timer expiration. Unfortunately, it doesn't check whether the pwq is already on the mayday list and unconditionally gets the ref and moves it onto the list. This doesn't corrupt the list but creates an additional reference to the pwq. It got queued twice but will only be removed once. This leak later can trigger pwq refcnt warning on workqueue destruction and prevent freeing of the workqueue. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: "Williams, Gerald S" <gerald.s.williams@intel.com> Cc: NeilBrown <neilb@suse.de> Cc: stable@vger.kernel.org # v3.19+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-12-17workqueue: Fix spurious sanity check failures in destroy_workqueue()Tejun Heo
commit def98c84b6cdf2eeea19ec5736e90e316df5206b upstream. Before actually destrying a workqueue, destroy_workqueue() checks whether it's actually idle. If it isn't, it prints out a bunch of warning messages and leaves the workqueue dangling. It unfortunately has a couple issues. * Mayday list queueing increments pwq's refcnts which gets detected as busy and fails the sanity checks. However, because mayday list queueing is asynchronous, this condition can happen without any actual work items left in the workqueue. * Sanity check failure leaves the sysfs interface behind too which can lead to init failure of newer instances of the workqueue. This patch fixes the above two by * If a workqueue has a rescuer, disable and kill the rescuer before sanity checks. Disabling and killing is guaranteed to flush the existing mayday list. * Remove sysfs interface before sanity checks. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Marcin Pawlowski <mpawlowski@fb.com> Reported-by: "Williams, Gerald S" <gerald.s.williams@intel.com> Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-09-13workqueue: require CPU hotplug read exclusion for apply_workqueue_attrsDaniel Jordan
Change the calling convention for apply_workqueue_attrs to require CPU hotplug read exclusion. Avoids lockdep complaints about nested calls to get_online_cpus in a future patch where padata calls apply_workqueue_attrs when changing other CPU-hotplug-sensitive data structures with the CPU read lock already held. Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Steffen Klassert <steffen.klassert@secunet.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-crypto@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2019-09-13workqueue: unconfine alloc/apply/free_workqueue_attrs()Daniel Jordan
padata will use these these interfaces in a later patch, so unconfine them. Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Steffen Klassert <steffen.klassert@secunet.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-crypto@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2019-06-27workqueue: Remove GPF argument from alloc_workqueue_attrs()Thomas Gleixner
All callers use GFP_KERNEL. No point in having that argument. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Tejun Heo <tj@kernel.org>
2019-06-27workqueue: Make alloc/apply/free_workqueue_attrs() staticThomas Gleixner
None of those functions have any users outside of workqueue.c. Confine them. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Tejun Heo <tj@kernel.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>
2019-05-09Merge branch 'for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wqLinus Torvalds
Pull workqueue updates from Tejun Heo: "Only three commits, of which two are trivial. The non-trivial chagne is Thomas's patch to switch workqueue from sched RCU to regular one. The use of sched RCU is mostly historic and doesn't really buy us anything noticeable" * 'for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: Use normal rcu kernel/workqueue: Document wq_worker_last_func() argument kernel/workqueue: Use __printf markup to silence compiler in function 'alloc_workqueue'
2019-05-07Merge tag 'printk-for-5.2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk Pull printk updates from Petr Mladek: - Allow state reset of printk_once() calls. - Prevent crashes when dereferencing invalid pointers in vsprintf(). Only the first byte is checked for simplicity. - Make vsprintf warnings consistent and inlined. - Treewide conversion of obsolete %pf, %pF to %ps, %pF printf modifiers. - Some clean up of vsprintf and test_printf code. * tag 'printk-for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk: lib/vsprintf: Make function pointer_string static vsprintf: Limit the length of inlined error messages vsprintf: Avoid confusion between invalid address and value vsprintf: Prevent crash when dereferencing invalid pointers vsprintf: Consolidate handling of unknown pointer specifiers vsprintf: Factor out %pO handler as kobject_string() vsprintf: Factor out %pV handler as va_format() vsprintf: Factor out %p[iI] handler as ip_addr_string() vsprintf: Do not check address of well-known strings vsprintf: Consistent %pK handling for kptr_restrict == 0 vsprintf: Shuffle restricted_pointer() printk: Tie printk_once / printk_deferred_once into .data.once for reset treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively lib/test_printf: Switch to bitmap_zalloc()
2019-04-16sched/core, workqueues: Distangle worker accounting from rq lockThomas Gleixner
The worker accounting for CPU bound workers is plugged into the core scheduler code and the wakeup code. This is not a hard requirement and can be avoided by keeping track of the state in the workqueue code itself. Keep track of the sleeping state in the worker itself and call the notifier before entering the core scheduler. There might be false positives when the task is woken between that call and actually scheduling, but that's not really different from scheduling and being woken immediately after switching away. When nr_running is updated when the task is retunrning from schedule() then it is later compared when it is done from ttwu(). [ bigeasy: preempt_disable() around wq_worker_sleeping() by Daniel Bristot de Oliveira ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Tejun Heo <tj@kernel.org> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/ad2b29b5715f970bffc1a7026cabd6ff0b24076a.1532952814.git.bristot@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-09treewide: Switch printk users from %pf and %pF to %ps and %pS, respectivelySakari Ailus
%pF and %pf are functionally equivalent to %pS and %ps conversion specifiers. The former are deprecated, therefore switch the current users to use the preferred variant. The changes have been produced by the following command: git grep -l '%p[fF]' | grep -v '^\(tools\|Documentation\)/' | \ while read i; do perl -i -pe 's/%pf/%ps/g; s/%pF/%pS/g;' $i; done And verifying the result. Link: http://lkml.kernel.org/r/20190325193229.23390-1-sakari.ailus@linux.intel.com Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: linux-arm-kernel@lists.infradead.org Cc: sparclinux@vger.kernel.org Cc: linux-um@lists.infradead.org Cc: xen-devel@lists.xenproject.org Cc: linux-acpi@vger.kernel.org Cc: linux-pm@vger.kernel.org Cc: drbd-dev@lists.linbit.com Cc: linux-block@vger.kernel.org Cc: linux-mmc@vger.kernel.org Cc: linux-nvdimm@lists.01.org Cc: linux-pci@vger.kernel.org Cc: linux-scsi@vger.kernel.org Cc: linux-btrfs@vger.kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net Cc: linux-mm@kvack.org Cc: ceph-devel@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Acked-by: David Sterba <dsterba@suse.com> (for btrfs) Acked-by: Mike Rapoport <rppt@linux.ibm.com> (for mm/memblock.c) Acked-by: Bjorn Helgaas <bhelgaas@google.com> (for drivers/pci) Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
2019-04-08workqueue: Use normal rcuThomas Gleixner
There is no need for sched_rcu. The undocumented reason why sched_rcu is used is to avoid a few explicit rcu_read_lock()/unlock() pairs by the fact that sched_rcu reader side critical sections are also protected by preempt or irq disabled regions. Replace rcu_read_lock_sched with rcu_read_lock and acquire the RCU lock where it is not yet explicit acquired. Replace local_irq_disable() with rcu_read_lock(). Update asserts. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bigeasy: mangle changelog a little] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Tejun Heo <tj@kernel.org>
2019-03-21workqueue: Only unregister a registered lockdep keyBart Van Assche
The recent change to prevent use after free and a memory leak introduced an unconditional call to wq_unregister_lockdep() in the error handling path. If the lockdep key had not been registered yet, then the lockdep core emits a warning. Only call wq_unregister_lockdep() if wq_register_lockdep() has been called first. Fixes: 009bb421b6ce ("workqueue, lockdep: Fix an alloc_workqueue() error path") Reported-by: syzbot+be0c198232f86389c3dd@syzkaller.appspotmail.com Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Tejun Heo <tj@kernel.org> Cc: Qian Cai <cai@lca.pw> Link: https://lkml.kernel.org/r/20190311230255.176081-1-bvanassche@acm.org
2019-03-19kernel/workqueue: Document wq_worker_last_func() argumentBart Van Assche
This patch avoids that the following warning is reported when building with W=1: kernel/workqueue.c:938: warning: Function parameter or member 'task' not described in 'wq_worker_last_func' Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Tejun Heo <tj@kernel.org>
2019-03-15kernel/workqueue: Use __printf markup to silence compiler in function ↵Mathieu Malaterre
'alloc_workqueue' Silence warnings (triggered at W=1) by adding relevant __printf attributes. kernel/workqueue.c:4249:2: warning: function 'alloc_workqueue' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format] Signed-off-by: Mathieu Malaterre <malat@debian.org> Signed-off-by: Tejun Heo <tj@kernel.org>
2019-03-10Merge branch 'locking-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking fixes from Thomas Gleixner: "A few fixes for lockdep: - initialize lockdep internal RCU head after initializing RCU - prevent use after free in a alloc_workqueue() error handling path - plug a memory leak in the workqueue core which fails to free a dynamically allocated lock name. - make Clang happy" * 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: workqueue, lockdep: Fix a memory leak in wq->lock_name workqueue, lockdep: Fix an alloc_workqueue() error path locking/lockdep: Only call init_rcu_head() after RCU has been initialized locking/lockdep: Avoid a Clang warning
2019-03-09workqueue, lockdep: Fix a memory leak in wq->lock_nameQian Cai
The following commit: 669de8bda87b ("kernel/workqueue: Use dynamic lockdep keys for workqueues") introduced a memory leak as wq_free_lockdep() calls kfree(wq->lock_name), but wq_init_lockdep() does not point wq->lock_name to the newly allocated slab object. This can be reproduced by running LTP fallocate04 followed by oom01 tests: unreferenced object 0xc0000005876384d8 (size 64): comm "fallocate04", pid 26972, jiffies 4297139141 (age 40370.480s) hex dump (first 32 bytes): 28 77 71 5f 63 6f 6d 70 6c 65 74 69 6f 6e 29 65 (wq_completion)e 78 74 34 2d 72 73 76 2d 63 6f 6e 76 65 72 73 69 xt4-rsv-conversi backtrace: [<00000000cb452883>] kvasprintf+0x6c/0xe0 [<000000004654ddac>] kasprintf+0x34/0x60 [<000000001c68f311>] alloc_workqueue+0x1f8/0x6ac [<0000000003c2ad83>] ext4_fill_super+0x23d4/0x3c80 [ext4] [<0000000006610538>] mount_bdev+0x25c/0x290 [<00000000bcf955ec>] ext4_mount+0x28/0x50 [ext4] [<0000000016e08fd3>] legacy_get_tree+0x4c/0xb0 [<0000000042b6a5fc>] vfs_get_tree+0x6c/0x190 [<00000000268ab022>] do_mount+0xb9c/0x1100 [<00000000698e6898>] ksys_mount+0x158/0x180 [<0000000064e391fd>] sys_mount+0x20/0x30 [<00000000ba378f12>] system_call+0x5c/0x70 Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: catalin.marinas@arm.com Cc: jiangshanlai@gmail.com Cc: tj@kernel.org Fixes: 669de8bda87b ("kernel/workqueue: Use dynamic lockdep keys for workqueues") Link: https://lkml.kernel.org/r/20190307002731.47371-1-cai@lca.pw Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-03-09workqueue, lockdep: Fix an alloc_workqueue() error pathBart Van Assche
This patch fixes a use-after-free and a memory leak in an alloc_workqueue() error path. Repoted by syzkaller and KASAN: BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:197 [inline] BUG: KASAN: use-after-free in lockdep_register_key+0x3b9/0x490 kernel/locking/lockdep.c:1023 Read of size 8 at addr ffff888090fc2698 by task syz-executor134/7858 CPU: 1 PID: 7858 Comm: syz-executor134 Not tainted 5.0.0-rc8-next-20190301 #1 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132 __read_once_size include/linux/compiler.h:197 [inline] lockdep_register_key+0x3b9/0x490 kernel/locking/lockdep.c:1023 wq_init_lockdep kernel/workqueue.c:3444 [inline] alloc_workqueue+0x427/0xe70 kernel/workqueue.c:4263 ucma_open+0x76/0x290 drivers/infiniband/core/ucma.c:1732 misc_open+0x398/0x4c0 drivers/char/misc.c:141 chrdev_open+0x247/0x6b0 fs/char_dev.c:417 do_dentry_open+0x488/0x1160 fs/open.c:771 vfs_open+0xa0/0xd0 fs/open.c:880 do_last fs/namei.c:3416 [inline] path_openat+0x10e9/0x46e0 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1063 __do_sys_openat fs/open.c:1090 [inline] __se_sys_openat fs/open.c:1084 [inline] __x64_sys_openat+0x9d/0x100 fs/open.c:1084 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Allocated by task 7789: save_stack+0x45/0xd0 mm/kasan/common.c:75 set_track mm/kasan/common.c:87 [inline] __kasan_kmalloc mm/kasan/common.c:497 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:470 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:511 __do_kmalloc mm/slab.c:3726 [inline] __kmalloc+0x15c/0x740 mm/slab.c:3735 kmalloc include/linux/slab.h:553 [inline] kzalloc include/linux/slab.h:743 [inline] alloc_workqueue+0x13c/0xe70 kernel/workqueue.c:4236 ucma_open+0x76/0x290 drivers/infiniband/core/ucma.c:1732 misc_open+0x398/0x4c0 drivers/char/misc.c:141 chrdev_open+0x247/0x6b0 fs/char_dev.c:417 do_dentry_open+0x488/0x1160 fs/open.c:771 vfs_open+0xa0/0xd0 fs/open.c:880 do_last fs/namei.c:3416 [inline] path_openat+0x10e9/0x46e0 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1063 __do_sys_openat fs/open.c:1090 [inline] __se_sys_openat fs/open.c:1084 [inline] __x64_sys_openat+0x9d/0x100 fs/open.c:1084 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 7789: save_stack+0x45/0xd0 mm/kasan/common.c:75 set_track mm/kasan/common.c:87 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:459 kasan_slab_free+0xe/0x10 mm/kasan/common.c:467 __cache_free mm/slab.c:3498 [inline] kfree+0xcf/0x230 mm/slab.c:3821 alloc_workqueue+0xc3e/0xe70 kernel/workqueue.c:4295 ucma_open+0x76/0x290 drivers/infiniband/core/ucma.c:1732 misc_open+0x398/0x4c0 drivers/char/misc.c:141 chrdev_open+0x247/0x6b0 fs/char_dev.c:417 do_dentry_open+0x488/0x1160 fs/open.c:771 vfs_open+0xa0/0xd0 fs/open.c:880 do_last fs/namei.c:3416 [inline] path_openat+0x10e9/0x46e0 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1063 __do_sys_openat fs/open.c:1090 [inline] __se_sys_openat fs/open.c:1084 [inline] __x64_sys_openat+0x9d/0x100 fs/open.c:1084 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888090fc2580 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 280 bytes inside of 512-byte region [ffff888090fc2580, ffff888090fc2780) Reported-by: syzbot+17335689e239ce135d8b@syzkaller.appspotmail.com Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Fixes: 669de8bda87b ("kernel/workqueue: Use dynamic lockdep keys for workqueues") Link: https://lkml.kernel.org/r/20190303220046.29448-1-bvanassche@acm.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-03-07Merge branch 'akpm' (patches from Andrew)Linus Torvalds
Merge more updates from Andrew Morton: - some of the rest of MM - various misc things - dynamic-debug updates - checkpatch - some epoll speedups - autofs - rapidio - lib/, lib/lzo/ updates * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (83 commits) samples/mic/mpssd/mpssd.h: remove duplicate header kernel/fork.c: remove duplicated include include/linux/relay.h: fix percpu annotation in struct rchan arch/nios2/mm/fault.c: remove duplicate include unicore32: stop printing the virtual memory layout MAINTAINERS: fix GTA02 entry and mark as orphan mm: create the new vm_fault_t type arm, s390, unicore32: remove oneliner wrappers for memblock_alloc() arch: simplify several early memory allocations openrisc: simplify pte_alloc_one_kernel() sh: prefer memblock APIs returning virtual address microblaze: prefer memblock API returning virtual address powerpc: prefer memblock APIs returning virtual address lib/lzo: separate lzo-rle from lzo lib/lzo: implement run-length encoding lib/lzo: fast 8-byte copy on arm64 lib/lzo: 64-bit CTZ on arm64 lib/lzo: tidy-up ifdefs ipc/sem.c: replace kvmalloc/memset with kvzalloc and use struct_size ipc: annotate implicit fall through ...
2019-03-07kernel: workqueue: clarify wq_worker_last_func() caller requirementsJohannes Weiner
This function can only be called safely from very specific scheduler contexts. Document those. Link: http://lkml.kernel.org/r/20190206150528.31198-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-07Merge branch 'for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wqLinus Torvalds
Pull workqueue updates from Tejun Heo: "All trivial. Two comment updates and one more initialization sanity check in flush_work()" * 'for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: Fix spelling in source code comments workqueue: fix typo in comment workqueue: Try to catch flush_work() without INIT_WORK().
2019-03-06Merge tag 'driver-core-5.1-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core updates from Greg KH: "Here is the big driver core patchset for 5.1-rc1 More patches than "normal" here this merge window, due to some work in the driver core by Alexander Duyck to rework the async probe functionality to work better for a number of devices, and independant work from Rafael for the device link functionality to make it work "correctly". Also in here is: - lots of BUS_ATTR() removals, the macro is about to go away - firmware test fixups - ihex fixups and simplification - component additions (also includes i915 patches) - lots of minor coding style fixups and cleanups. All of these have been in linux-next for a while with no reported issues" * tag 'driver-core-5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (65 commits) driver core: platform: remove misleading err_alloc label platform: set of_node in platform_device_register_full() firmware: hardcode the debug message for -ENOENT driver core: Add missing description of new struct device_link field driver core: Fix PM-runtime for links added during consumer probe drivers/component: kerneldoc polish async: Add cmdline option to specify drivers to be async probed driver core: Fix possible supplier PM-usage counter imbalance PM-runtime: Fix __pm_runtime_set_status() race with runtime resume driver: platform: Support parsing GpioInt 0 in platform_get_irq() selftests: firmware: fix verify_reqs() return value Revert "selftests: firmware: remove use of non-standard diff -Z option" Revert "selftests: firmware: add CONFIG_FW_LOADER_USER_HELPER_FALLBACK to config" device: Fix comment for driver_data in struct device kernfs: Allocating memory for kernfs_iattrs with kmem_cache. sysfs: remove unused include of kernfs-internal.h driver core: Postpone DMA tear-down until after devres release driver core: Document limitation related to DL_FLAG_RPM_ACTIVE PM-runtime: Take suppliers into account in __pm_runtime_set_status() device.h: Add __cold to dev_<level> logging functions ...
2019-03-05workqueue: Fix spelling in source code commentsBart Van Assche
Change "execuing" into "executing" and "guarnateed" into "guaranteed". Cc: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Tejun Heo <tj@kernel.org>
2019-02-28kernel/workqueue: Use dynamic lockdep keys for workqueuesBart Van Assche
The following commit: 87915adc3f0a ("workqueue: re-add lockdep dependencies for flushing") improved deadlock checking in the workqueue implementation. Unfortunately that patch also introduced a few false positive lockdep complaints. This patch suppresses these false positives by allocating the workqueue mutex lockdep key dynamically. An example of a false positive lockdep complaint suppressed by this patch can be found below. The root cause of the lockdep complaint shown below is that the direct I/O code can call alloc_workqueue() from inside a work item created by another alloc_workqueue() call and that both workqueues share the same lockdep key. This patch avoids that that lockdep complaint is triggered by allocating the work queue lockdep keys dynamically. In other words, this patch guarantees that a unique lockdep key is associated with each work queue mutex. ====================================================== WARNING: possible circular locking dependency detected 4.19.0-dbg+ #1 Not tainted fio/4129 is trying to acquire lock: 00000000a01cfe1a ((wq_completion)"dio/%s"sb->s_id){+.+.}, at: flush_workqueue+0xd0/0x970 but task is already holding lock: 00000000a0acecf9 (&sb->s_type->i_mutex_key#14){+.+.}, at: ext4_file_write_iter+0x154/0x710 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&sb->s_type->i_mutex_key#14){+.+.}: down_write+0x3d/0x80 __generic_file_fsync+0x77/0xf0 ext4_sync_file+0x3c9/0x780 vfs_fsync_range+0x66/0x100 dio_complete+0x2f5/0x360 dio_aio_complete_work+0x1c/0x20 process_one_work+0x481/0x9f0 worker_thread+0x63/0x5a0 kthread+0x1cf/0x1f0 ret_from_fork+0x24/0x30 -> #1 ((work_completion)(&dio->complete_work)){+.+.}: process_one_work+0x447/0x9f0 worker_thread+0x63/0x5a0 kthread+0x1cf/0x1f0 ret_from_fork+0x24/0x30 -> #0 ((wq_completion)"dio/%s"sb->s_id){+.+.}: lock_acquire+0xc5/0x200 flush_workqueue+0xf3/0x970 drain_workqueue+0xec/0x220 destroy_workqueue+0x23/0x350 sb_init_dio_done_wq+0x6a/0x80 do_blockdev_direct_IO+0x1f33/0x4be0 __blockdev_direct_IO+0x79/0x86 ext4_direct_IO+0x5df/0xbb0 generic_file_direct_write+0x119/0x220 __generic_file_write_iter+0x131/0x2d0 ext4_file_write_iter+0x3fa/0x710 aio_write+0x235/0x330 io_submit_one+0x510/0xeb0 __x64_sys_io_submit+0x122/0x340 do_syscall_64+0x71/0x220 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: (wq_completion)"dio/%s"sb->s_id --> (work_completion)(&dio->complete_work) --> &sb->s_type->i_mutex_key#14 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#14); lock((work_completion)(&dio->complete_work)); lock(&sb->s_type->i_mutex_key#14); lock((wq_completion)"dio/%s"sb->s_id); *** DEADLOCK *** 1 lock held by fio/4129: #0: 00000000a0acecf9 (&sb->s_type->i_mutex_key#14){+.+.}, at: ext4_file_write_iter+0x154/0x710 stack backtrace: CPU: 3 PID: 4129 Comm: fio Not tainted 4.19.0-dbg+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 Call Trace: dump_stack+0x86/0xc5 print_circular_bug.isra.32+0x20a/0x218 __lock_acquire+0x1c68/0x1cf0 lock_acquire+0xc5/0x200 flush_workqueue+0xf3/0x970 drain_workqueue+0xec/0x220 destroy_workqueue+0x23/0x350 sb_init_dio_done_wq+0x6a/0x80 do_blockdev_direct_IO+0x1f33/0x4be0 __blockdev_direct_IO+0x79/0x86 ext4_direct_IO+0x5df/0xbb0 generic_file_direct_write+0x119/0x220 __generic_file_write_iter+0x131/0x2d0 ext4_file_write_iter+0x3fa/0x710 aio_write+0x235/0x330 io_submit_one+0x510/0xeb0 __x64_sys_io_submit+0x122/0x340 do_syscall_64+0x71/0x220 entry_SYSCALL_64_after_hwframe+0x49/0xbe Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Johannes Berg <johannes.berg@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will.deacon@arm.com> Link: https://lkml.kernel.org/r/20190214230058.196511-20-bvanassche@acm.org [ Reworked the changelog a bit. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-21workqueue: fix typo in commentLiu Song
qeueue/queue Signed-off-by: Liu Song <liu.song11@zte.com.cn> Signed-off-by: Tejun Heo <tj@kernel.org>
2019-02-11Merge 5.0-rc6 into driver-core-nextGreg Kroah-Hartman
We need the debugfs fixes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-02-01psi: fix aggregation idle shut-offJohannes Weiner
psi has provisions to shut off the periodic aggregation worker when there is a period of no task activity - and thus no data that needs aggregating. However, while developing psi monitoring, Suren noticed that the aggregation clock currently won't stay shut off for good. Debugging this revealed a flaw in the idle design: an aggregation run will see no task activity and decide to go to sleep; shortly thereafter, the kworker thread that executed the aggregation will go idle and cause a scheduling change, during which the psi callback will kick the !pending worker again. This will ping-pong forever, and is equivalent to having no shut-off logic at all (but with more code!) Fix this by exempting aggregation workers from psi's clock waking logic when the state change is them going to sleep. To do this, tag workers with the last work function they executed, and if in psi we see a worker going to sleep after aggregating psi data, we will not reschedule the aggregation work item. What if the worker is also executing other items before or after? Any psi state times that were incurred by work items preceding the aggregation work will have been collected from the per-cpu buckets during the aggregation itself. If there are work items following the aggregation work, the worker's last_func tag will be overwritten and the aggregator will be kept alive to process this genuine new activity. If the aggregation work is the last thing the worker does, and we decide to go idle, the brief period of non-idle time incurred between the aggregation run and the kworker's dequeue will be stranded in the per-cpu buckets until the clock is woken by later activity. But that should not be a problem. The buckets can hold 4s worth of time, and future activity will wake the clock with a 2s delay, giving us 2s worth of data we can leave behind when disabling aggregation. If it takes a worker more than two seconds to go idle after it finishes its last work item, we likely have bigger problems in the system, and won't notice one sample that was averaged with a bogus per-CPU weight. Link: http://lkml.kernel.org/r/20190116193501.1910-1-hannes@cmpxchg.org Fixes: eb414681d5a0 ("psi: pressure stall information for CPU, memory, and IO") Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Suren Baghdasaryan <surenb@google.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-31workqueue: Provide queue_work_node to queue work near a given NUMA nodeAlexander Duyck
Provide a new function, queue_work_node, which is meant to schedule work on a "random" CPU of the requested NUMA node. The main motivation for this is to help assist asynchronous init to better improve boot times for devices that are local to a specific node. For now we just default to the first CPU that is in the intersection of the cpumask of the node and the online cpumask. The only exception is if the CPU is local to the node we will just use the current CPU. This should work for our purposes as we are currently only using this for unbound work so the CPU will be translated to a node anyway instead of being directly used. As we are only using the first CPU to represent the NUMA node for now I am limiting the scope of the function so that it can only be used with unbound workqueues. Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Acked-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-01-25workqueue: Try to catch flush_work() without INIT_WORK().Tetsuo Handa
syzbot found a flush_work() caller who forgot to call INIT_WORK() because that work_struct was allocated by kzalloc() [1]. But the message INFO: trying to register non-static key. the code is fine but needs lockdep annotation. turning off the locking correctness validator. by lock_map_acquire() is failing to tell that INIT_WORK() is missing. Since flush_work() without INIT_WORK() is a bug, and INIT_WORK() should set ->func field to non-zero, let's warn if ->func field is zero. [1] https://syzkaller.appspot.com/bug?id=a5954455fcfa51c29ca2ab55b203076337e1c770 Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Tejun Heo <tj@kernel.org>
2018-11-27workqueue: Replace call_rcu_sched() with call_rcu()Paul E. McKenney
Now that call_rcu()'s callback is not invoked until after all preempt-disable regions of code have completed (in addition to explicitly marked RCU read-side critical sections), call_rcu() can be used in place of call_rcu_sched(). This commit therefore makes that change. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Acked-by: Tejun Heo <tj@kernel.org>
2018-08-30watchdog: Mark watchdog touch functions as notraceVincent Whitchurch
Some architectures need to use stop_machine() to patch functions for ftrace, and the assumption is that the stopped CPUs do not make function calls to traceable functions when they are in the stopped state. Commit ce4f06dcbb5d ("stop_machine: Touch_nmi_watchdog() after MULTI_STOP_PREPARE") added calls to the watchdog touch functions from the stopped CPUs and those functions lack notrace annotations. This leads to crashes when enabling/disabling ftrace on ARM kernels built with the Thumb-2 instruction set. Fix it by adding the necessary notrace annotations. Fixes: ce4f06dcbb5d ("stop_machine: Touch_nmi_watchdog() after MULTI_STOP_PREPARE") Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: oleg@redhat.com Cc: tj@kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180821152507.18313-1-vincent.whitchurch@axis.com
2018-08-24Merge branch 'for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wqLinus Torvalds
Pull workqueue updates from Tejun Heo: "Over the lockdep cross-release churn, workqueue lost some of the existing annotations. Johannes Berg restored it and also improved them" * 'for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: re-add lockdep dependencies for flushing workqueue: skip lockdep wq dependency in cancel_work_sync()
2018-08-22workqueue: re-add lockdep dependencies for flushingJohannes Berg
In flush_work(), we need to create a lockdep dependency so that the following scenario is appropriately tagged as a problem: work_function() { mutex_lock(&mutex); ... } other_function() { mutex_lock(&mutex); flush_work(&work); // or cancel_work_sync(&work); } This is a problem since the work might be running and be blocked on trying to acquire the mutex. Similarly, in flush_workqueue(). These were removed after cross-release partially caught these problems, but now cross-release was reverted anyway. IMHO the removal was erroneous anyway though, since lockdep should be able to catch potential problems, not just actual ones, and cross-release would only have caught the problem when actually invoking wait_for_completion(). Fixes: fd1a5b04dfb8 ("workqueue: Remove now redundant lock acquisitions wrt. workqueue flushes") Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2018-08-22workqueue: skip lockdep wq dependency in cancel_work_sync()Johannes Berg
In cancel_work_sync(), we can only have one of two cases, even with an ordered workqueue: * the work isn't running, just cancelled before it started * the work is running, but then nothing else can be on the workqueue before it Thus, we need to skip the lockdep workqueue dependency handling, otherwise we get false positive reports from lockdep saying that we have a potential deadlock when the workqueue also has other work items with locking, e.g. work1_function() { mutex_lock(&mutex); ... } work2_function() { /* nothing */ } other_function() { queue_work(ordered_wq, &work1); queue_work(ordered_wq, &work2); mutex_lock(&mutex); cancel_work_sync(&work2); } As described above, this isn't a problem, but lockdep will currently flag it as if cancel_work_sync() was flush_work(), which *is* a problem. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2018-06-12treewide: kzalloc() -> kcalloc()Kees Cook
The kzalloc() function has a 2-factor argument form, kcalloc(). This patch replaces cases of: kzalloc(a * b, gfp) with: kcalloc(a * b, gfp) as well as handling cases of: kzalloc(a * b * c, gfp) with: kzalloc(array3_size(a, b, c), gfp) as it's slightly less ugly than: kzalloc_array(array_size(a, b), c, gfp) This does, however, attempt to ignore constant size factors like: kzalloc(4 * 1024, gfp) though any constants defined via macros get caught up in the conversion. Any factors with a sizeof() of "unsigned char", "char", and "u8" were dropped, since they're redundant. The Coccinelle script used for this was: // Fix redundant parens around sizeof(). @@ type TYPE; expression THING, E; @@ ( kzalloc( - (sizeof(TYPE)) * E + sizeof(TYPE) * E , ...) | kzalloc( - (sizeof(THING)) * E + sizeof(THING) * E , ...) ) // Drop single-byte sizes and redundant parens. @@ expression COUNT; typedef u8; typedef __u8; @@ ( kzalloc( - sizeof(u8) * (COUNT) + COUNT , ...) | kzalloc( - sizeof(__u8) * (COUNT) + COUNT , ...) | kzalloc( - sizeof(char) * (COUNT) + COUNT , ...) | kzalloc( - sizeof(unsigned char) * (COUNT) + COUNT , ...) | kzalloc( - sizeof(u8) * COUNT + COUNT , ...) | kzalloc( - sizeof(__u8) * COUNT + COUNT , ...) | kzalloc( - sizeof(char) * COUNT + COUNT , ...) | kzalloc( - sizeof(unsigned char) * COUNT + COUNT , ...) ) // 2-factor product with sizeof(type/expression) and identifier or constant. @@ type TYPE; expression THING; identifier COUNT_ID; constant COUNT_CONST; @@ ( - kzalloc + kcalloc ( - sizeof(TYPE) * (COUNT_ID) + COUNT_ID, sizeof(TYPE) , ...) | - kzalloc + kcalloc ( - sizeof(TYPE) * COUNT_ID + COUNT_ID, sizeof(TYPE) , ...) | - kzalloc + kcalloc ( - sizeof(TYPE) * (COUNT_CONST) + COUNT_CONST, sizeof(TYPE) , ...) | - kzalloc + kcalloc ( - sizeof(TYPE) * COUNT_CONST + COUNT_CONST, sizeof(TYPE) , ...) | - kzalloc + kcalloc ( - sizeof(THING) * (COUNT_ID) + COUNT_ID, sizeof(THING) , ...) | - kzalloc + kcalloc ( - sizeof(THING) * COUNT_ID + COUNT_ID, sizeof(THING) , ...) | - kzalloc + kcalloc ( - sizeof(THING) * (COUNT_CONST) + COUNT_CONST, sizeof(THING) , ...) | - kzalloc + kcalloc ( - sizeof(THING) * COUNT_CONST + COUNT_CONST, sizeof(THING) , ...) ) // 2-factor product, only identifiers. @@ identifier SIZE, COUNT; @@ - kzalloc + kcalloc ( - SIZE * COUNT + COUNT, SIZE , ...) // 3-factor product with 1 sizeof(type) or sizeof(expression), with // redundant parens removed. @@ expression THING; identifier STRIDE, COUNT; type TYPE; @@ ( kzalloc( - sizeof(TYPE) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc( - sizeof(TYPE) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc( - sizeof(TYPE) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc( - sizeof(TYPE) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc( - sizeof(THING) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kzalloc( - sizeof(THING) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kzalloc( - sizeof(THING) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kzalloc( - sizeof(THING) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) ) // 3-factor product with 2 sizeof(variable), with redundant parens removed. @@ expression THING1, THING2; identifier COUNT; type TYPE1, TYPE2; @@ ( kzalloc( - sizeof(TYPE1) * sizeof(TYPE2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kzalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kzalloc( - sizeof(THING1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kzalloc( - sizeof(THING1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kzalloc( - sizeof(TYPE1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) | kzalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) ) // 3-factor product, only identifiers, with redundant parens removed. @@ identifier STRIDE, SIZE, COUNT; @@ ( kzalloc( - (COUNT) * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - COUNT * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - COUNT * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - (COUNT) * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - COUNT * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - (COUNT) * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - (COUNT) * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc( - COUNT * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) ) // Any remaining multi-factor products, first at least 3-factor products, // when they're not all constants... @@ expression E1, E2, E3; constant C1, C2, C3; @@ ( kzalloc(C1 * C2 * C3, ...) | kzalloc( - (E1) * E2 * E3 + array3_size(E1, E2, E3) , ...) | kzalloc( - (E1) * (E2) * E3 + array3_size(E1, E2, E3) , ...) | kzalloc( - (E1) * (E2) * (E3) + array3_size(E1, E2, E3) , ...) | kzalloc( - E1 * E2 * E3 + array3_size(E1, E2, E3) , ...) ) // And then all remaining 2 factors products when they're not all constants, // keeping sizeof() as the second factor argument. @@ expression THING, E1, E2; type TYPE; constant C1, C2, C3; @@ ( kzalloc(sizeof(THING) * C2, ...) | kzalloc(sizeof(TYPE) * C2, ...) | kzalloc(C1 * C2 * C3, ...) | kzalloc(C1 * C2, ...) | - kzalloc + kcalloc ( - sizeof(TYPE) * (E2) + E2, sizeof(TYPE) , ...) | - kzalloc + kcalloc ( - sizeof(TYPE) * E2 + E2, sizeof(TYPE) , ...) | - kzalloc + kcalloc ( - sizeof(THING) * (E2) + E2, sizeof(THING) , ...) | - kzalloc + kcalloc ( - sizeof(THING) * E2 + E2, sizeof(THING) , ...) | - kzalloc + kcalloc ( - (E1) * E2 + E1, E2 , ...) | - kzalloc + kcalloc ( - (E1) * (E2) + E1, E2 , ...) | - kzalloc + kcalloc ( - E1 * E2 + E1, E2 , ...) ) Signed-off-by: Kees Cook <keescook@chromium.org>
2018-06-10Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsiLinus Torvalds
Pull SCSI updates from James Bottomley: "This is mostly updates to the usual drivers: ufs, qedf, mpt3sas, lpfc, xfcp, hisi_sas, cxlflash, qla2xxx. In the absence of Nic, we're also taking target updates which are mostly minor except for the tcmu refactor. The only real core change to worry about is the removal of high page bouncing (in sas, storvsc and iscsi). This has been well tested and no problems have shown up so far" * tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (268 commits) scsi: lpfc: update driver version to 12.0.0.4 scsi: lpfc: Fix port initialization failure. scsi: lpfc: Fix 16gb hbas failing cq create. scsi: lpfc: Fix crash in blk_mq layer when executing modprobe -r lpfc scsi: lpfc: correct oversubscription of nvme io requests for an adapter scsi: lpfc: Fix MDS diagnostics failure (Rx < Tx) scsi: hisi_sas: Mark PHY as in reset for nexus reset scsi: hisi_sas: Fix return value when get_free_slot() failed scsi: hisi_sas: Terminate STP reject quickly for v2 hw scsi: hisi_sas: Add v2 hw force PHY function for internal ATA command scsi: hisi_sas: Include TMF elements in struct hisi_sas_slot scsi: hisi_sas: Try wait commands before before controller reset scsi: hisi_sas: Init disks after controller reset scsi: hisi_sas: Create a scsi_host_template per HW module scsi: hisi_sas: Reset disks when discovered scsi: hisi_sas: Add LED feature for v3 hw scsi: hisi_sas: Change common allocation mode of device id scsi: hisi_sas: change slot index allocation mode scsi: hisi_sas: Introduce hisi_sas_phy_set_linkrate() scsi: hisi_sas: fix a typo in hisi_sas_task_prep() ...
2018-06-06Merge tag 'overflow-v4.18-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull overflow updates from Kees Cook: "This adds the new overflow checking helpers and adds them to the 2-factor argument allocators. And this adds the saturating size helpers and does a treewide replacement for the struct_size() usage. Additionally this adds the overflow testing modules to make sure everything works. I'm still working on the treewide replacements for allocators with "simple" multiplied arguments: *alloc(a * b, ...) -> *alloc_array(a, b, ...) and *zalloc(a * b, ...) -> *calloc(a, b, ...) as well as the more complex cases, but that's separable from this portion of the series. I expect to have the rest sent before -rc1 closes; there are a lot of messy cases to clean up. Summary: - Introduce arithmetic overflow test helper functions (Rasmus) - Use overflow helpers in 2-factor allocators (Kees, Rasmus) - Introduce overflow test module (Rasmus, Kees) - Introduce saturating size helper functions (Matthew, Kees) - Treewide use of struct_size() for allocators (Kees)" * tag 'overflow-v4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: treewide: Use struct_size() for devm_kmalloc() and friends treewide: Use struct_size() for vmalloc()-family treewide: Use struct_size() for kmalloc()-family device: Use overflow helpers for devm_kmalloc() mm: Use overflow helpers in kvmalloc() mm: Use overflow helpers in kmalloc_array*() test_overflow: Add memory allocation overflow tests overflow.h: Add allocation size calculation helpers test_overflow: Report test failures test_overflow: macrofy some more, do more tests for free lib: add runtime test of check_*_overflow functions compiler.h: enable builtin overflow checkers and add fallback code
2018-06-06treewide: Use struct_size() for kmalloc()-familyKees Cook
One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example: struct foo { int stuff; void *entry[]; }; instance = kmalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL); Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper: instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL); This patch makes the changes for kmalloc()-family (and kvmalloc()-family) uses. It was done via automatic conversion with manual review for the "CHECKME" non-standard cases noted below, using the following Coccinelle script: // pkey_cache = kmalloc(sizeof *pkey_cache + tprops->pkey_tbl_len * // sizeof *pkey_cache->table, GFP_KERNEL); @@ identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc"; expression GFP; identifier VAR, ELEMENT; expression COUNT; @@ - alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT), GFP) + alloc(struct_size(VAR, ELEMENT, COUNT), GFP) // mr = kzalloc(sizeof(*mr) + m * sizeof(mr->map[0]), GFP_KERNEL); @@ identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc"; expression GFP; identifier VAR, ELEMENT; expression COUNT; @@ - alloc(sizeof(*VAR) + COUNT * sizeof(VAR->ELEMENT[0]), GFP) + alloc(struct_size(VAR, ELEMENT, COUNT), GFP) // Same pattern, but can't trivially locate the trailing element name, // or variable name. @@ identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc"; expression GFP; expression SOMETHING, COUNT, ELEMENT; @@ - alloc(sizeof(SOMETHING) + COUNT * sizeof(ELEMENT), GFP) + alloc(CHECKME_struct_size(&SOMETHING, ELEMENT, COUNT), GFP) Signed-off-by: Kees Cook <keescook@chromium.org>
2018-05-23workqueue: move function definitions within CONFIG_SMP blockMathieu Malaterre
In commit 7ee681b25284 ("workqueue: Convert to state machine callbacks"), three new function definitions were added: ‘workqueue_prepare_cpu’, ‘workqueue_online_cpu’ and ‘workqueue_offline_cpu’. Move these function definitions within a CONFIG_SMP block since they are not used outside of it. This will match function declarations in header <include/linux/workqueue.h>, and silence the following gcc warning (W=1): kernel/workqueue.c:4743:5: warning: no previous prototype for ‘workqueue_prepare_cpu’ [-Wmissing-prototypes] kernel/workqueue.c:4756:5: warning: no previous prototype for ‘workqueue_online_cpu’ [-Wmissing-prototypes] kernel/workqueue.c:4783:5: warning: no previous prototype for ‘workqueue_offline_cpu’ [-Wmissing-prototypes] Signed-off-by: Mathieu Malaterre <malat@debian.org> Signed-off-by: Tejun Heo <tj@kernel.org>