diff options
author | Tejun Heo <tj@kernel.org> | 2015-12-07 10:58:57 -0500 |
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committer | Tejun Heo <tj@kernel.org> | 2015-12-08 11:29:36 -0500 |
commit | fca839c00a12d682cb59b3b620d109a1d850b262 (patch) | |
tree | 5e7930d002412222645eca18e77343969262f75c /kernel/workqueue.c | |
parent | 527e9316f8ec44bd53d90fb9f611fa7ffff52bb9 (diff) | |
download | linux-fca839c00a12d682cb59b3b620d109a1d850b262.tar.bz2 |
workqueue: warn if memory reclaim tries to flush !WQ_MEM_RECLAIM workqueue
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>
Diffstat (limited to 'kernel/workqueue.c')
-rw-r--r-- | kernel/workqueue.c | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index c579dbab2e36..c7769c507bf5 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -2316,6 +2316,37 @@ repeat: goto repeat; } +/** + * check_flush_dependency - check for flush dependency sanity + * @target_wq: workqueue being flushed + * @target_work: work item being flushed (NULL for workqueue flushes) + * + * %current is trying to flush the whole @target_wq or @target_work on it. + * If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not + * reclaiming memory or running on a workqueue which doesn't have + * %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to + * a deadlock. + */ +static void check_flush_dependency(struct workqueue_struct *target_wq, + struct work_struct *target_work) +{ + work_func_t target_func = target_work ? target_work->func : NULL; + struct worker *worker; + + if (target_wq->flags & WQ_MEM_RECLAIM) + return; + + worker = current_wq_worker(); + + WARN_ONCE(current->flags & PF_MEMALLOC, + "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%pf", + current->pid, current->comm, target_wq->name, target_func); + WARN_ONCE(worker && (worker->current_pwq->wq->flags & WQ_MEM_RECLAIM), + "workqueue: WQ_MEM_RECLAIM %s:%pf is flushing !WQ_MEM_RECLAIM %s:%pf", + worker->current_pwq->wq->name, worker->current_func, + target_wq->name, target_func); +} + struct wq_barrier { struct work_struct work; struct completion done; @@ -2525,6 +2556,8 @@ void flush_workqueue(struct workqueue_struct *wq) list_add_tail(&this_flusher.list, &wq->flusher_overflow); } + check_flush_dependency(wq, NULL); + mutex_unlock(&wq->mutex); wait_for_completion(&this_flusher.done); @@ -2697,6 +2730,8 @@ static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) pwq = worker->current_pwq; } + check_flush_dependency(pwq->wq, work); + insert_wq_barrier(pwq, barr, work, worker); spin_unlock_irq(&pool->lock); |