On 2021-12-26 16:20:30 [-0800], Andrew Morton wrote: > On Thu, 23 Dec 2021 19:15:09 +0100 Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> 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
