lkml.org 
[lkml]   [2022]   [Jan]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH REPOST REPOST v2] fscache: Use only one fscache_object_cong_wait.
On 2021-12-26 16:20:30 [-0800], Andrew Morton wrote:
> On Thu, 23 Dec 2021 19:15:09 +0100 Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote:
>
> > On 2021-12-23 17:17:09 [+0000], David Howells wrote:
> > > Thanks, but this is gone in the upcoming fscache rewrite. I'm hoping that
> > > will get in the next merge window.
> >
> > Yes, I noticed that. What about current tree, v5.16-rc6 and less?
> > Shouldn't this be addressed?
>
> If the bug is serious enough to justify a -stable backport then yes, we
> should merge a fix such as this ahead of the fscache rewrite, so we
> have something suitable for backporting.
>
> Is the bug serious enough?
>
> Or is the bug in a not-yet-noticed state? In other words, is it
> possible that four years from now, someone will hit this bug in a
> 5.15-based kernel and will then wish we'd backported a fix?

I can't answer how serious it is but:
- with CONFIG_DEBUG_PREEMPT enabled there has to be a visible backtrace
due this_cpu_ptr() usage.
- because of schedule_timeout(60 * HZ) there is no visible hang. It
should be either woken up properly (via the waitqueue) or after a
minute due to the timeout.

both things don't look good in general.

Sebastian

\
 
 \ /
  Last update: 2022-01-03 14:55    [W:0.043 / U:0.252 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site