Re: calling flush_scheduled_work()

From: Andrew Morton
Date: Fri Mar 12 2004 - 18:28:27 EST


Tim Hockin <thockin@xxxxxxx> wrote:
>
> We've recently bumped into an issue, and I'm not sure which is the real bug.
>
> In short we have a case where mntput() is called from the kevetd workqueue.
> When that mntput() hit an NFS mount, we got a deadlock. It turns out that
> deep in the RPC code, someone calls flush_scheduled_work(). Deadlock.

Seems simple enough to fix the workqueue code to handle this situation.

Wanna test this for me?

---

25-akpm/kernel/workqueue.c | 8 ++++++++
1 files changed, 8 insertions(+)

diff -puN kernel/workqueue.c~flush_scheduled_work-deadlock-fix kernel/workqueue.c
--- 25/kernel/workqueue.c~flush_scheduled_work-deadlock-fix Fri Mar 12 15:24:29 2004
+++ 25-akpm/kernel/workqueue.c Fri Mar 12 15:25:46 2004
@@ -229,6 +229,14 @@ void fastcall flush_workqueue(struct wor
continue;
cwq = wq->cpu_wq + cpu;

+ if (cwq->thread == current) {
+ /*
+ * Probably keventd trying to flush its own queue.
+ * So just run it by hand rather than deadlocking
+ */
+ run_workqueue(cwq);
+ continue;
+ }
spin_lock_irq(&cwq->lock);
sequence_needed = cwq->insert_sequence;


_

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