Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug()

From: Linus Torvalds
Date: Thu Sep 17 2015 - 19:14:04 EST


On Thu, Sep 17, 2015 at 4:03 PM, Dave Chinner <david@xxxxxxxxxxxxx> wrote:
>
> Ok, I'm happy to report there is actually nothing wrong with the
> plugging code that is your tree. I finally tracked the problem I
> was seeing down to a misbehaving RAID controller.[*]

Hey, that's great.

Just out of interest, try the patch that Chris just sent that turns
the unplugging synchronous for the special "cond_resched()" case.

If that helps your case too, let's just do it, even while we wonder
why kblockd_workqueue messes up so noticeable.

Because regardless of the kblockd_workqueue questions, I think it's
nicer to avoid the cond_resched_lock(), and do the rescheduling while
we're not holding any locks.

Linus
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