From: Donald Buczek <email@example.com>
To: Brian Foster <firstname.lastname@example.org>
Cc: Dave Chinner <email@example.com>,
Linux Kernel Mailing List <firstname.lastname@example.org>,
Subject: Re: [PATCH] xfs: Wake CIL push waiters more reliably
Date: Tue, 16 Feb 2021 13:40:35 +0100 [thread overview]
Message-ID: <email@example.com> (raw)
On 16.02.21 12:18, Brian Foster wrote:
> On Mon, Feb 15, 2021 at 02:36:38PM +0100, Donald Buczek wrote:
>> On 13.01.21 22:53, Dave Chinner wrote:
>>> I agree that a throttling fix is needed, but I'm trying to
>>> understand the scope and breadth of the problem first instead of
>>> jumping the gun and making the wrong fix for the wrong reasons that
>>> just papers over the underlying problems that the throttling bug has
>>> made us aware of...
>> Are you still working on this?
>> If it takes more time to understand the potential underlying problem, the fix for the problem at hand should be applied.
>> This is a real world problem, accidentally found in the wild. It appears very rarely, but it freezes a filesystem or the whole system. It exists in 5.7 , 5.8 , 5.9 , 5.10 and 5.11 and is caused by c7f87f3984cf ("xfs: fix use-after-free on CIL context on shutdown") which silently added a condition to the wakeup. The condition is based on a wrong assumption.
>> Why is this "papering over"? If a reminder was needed, there were better ways than randomly hanging the system.
>> Why is
>> if (ctx->space_used >= XLOG_CIL_BLOCKING_SPACE_LIMIT(log))
>> , which doesn't work reliably, preferable to
>> if (waitqueue_active(&cil->xc_push_wait))
>> which does?
> JFYI, Dave followed up with a patch a couple weeks or so ago:
Oh, great. I apologize for the unneeded reminder.
next prev parent reply other threads:[~2021-02-16 12:41 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-17 17:44 v5.10.1 xfs deadlock Donald Buczek
2020-12-17 19:43 ` Brian Foster
2020-12-17 21:30 ` Donald Buczek
2020-12-18 15:35 ` Brian Foster
2020-12-18 18:35 ` Donald Buczek
2020-12-27 17:34 ` Donald Buczek
2020-12-28 23:13 ` Donald Buczek
2020-12-29 23:56 ` [PATCH] xfs: Wake CIL push waiters more reliably Donald Buczek
2020-12-30 22:16 ` Dave Chinner
2020-12-31 11:48 ` Donald Buczek
2020-12-31 21:59 ` Dave Chinner
2021-01-02 19:12 ` Donald Buczek
2021-01-02 22:44 ` Dave Chinner
2021-01-03 16:03 ` Donald Buczek
2021-01-07 22:19 ` Dave Chinner
2021-01-09 14:39 ` Donald Buczek
2021-01-04 16:23 ` Brian Foster
2021-01-07 21:54 ` Dave Chinner
2021-01-08 16:56 ` Brian Foster
2021-01-11 16:38 ` Brian Foster
2021-01-13 21:53 ` Dave Chinner
2021-02-15 13:36 ` Donald Buczek
2021-02-16 11:18 ` Brian Foster
2021-02-16 12:40 ` Donald Buczek [this message]
2021-01-13 21:44 ` Dave Chinner
[not found] ` <firstname.lastname@example.org>
2020-12-30 16:54 ` Donald Buczek
2020-12-18 21:49 ` v5.10.1 xfs deadlock Dave Chinner
2020-12-21 12:22 ` Donald Buczek
2020-12-27 17:22 ` Donald Buczek
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