On Thu, Apr 05, 2018 at 06:04:12PM +0300, Nikolay Borisov wrote:
>
>
> On 5.04.2018 16:55, David Sterba wrote:
> > On Thu, Apr 05, 2018 at 10:40:15AM +0300, Nikolay Borisov wrote:
> >> do_chunk_alloc implements a loop checking whether there is a pending
> >> chunk allocation and if so causes the caller do loop. Generally this
> >> loop is executed only once, however testing with btrfs/072 on a
> >> single core vm machines uncovered an extreme case where the system
> >> could loop indefinitely. This is due to a missing cond_resched when
> >> loop which doesn't give a chance to the previous chunk allocator finish
> >> its job.
> >>
> >> The fix is to simply add the missing cond_resched.
> >>
> >> Fixes: 6d74119f1a3e ("Btrfs: avoid taking the chunk_mutex in
> >> do_chunk_alloc")
> >
> > Does this commit really lead to the endless loop on UP? I don't see any
> > obvious connection.
>
> This is the commit that introduced the loop there without adding
> cond_resched, hence the fixes tag.
Makes sense, thanks.
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