Re: [PATCH] kasan: resched in quarantine_remove_cache()

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On Wed,  8 Mar 2017 16:42:39 +0100 Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:

> We see reported stalls/lockups in quarantine_remove_cache() on machines
> with large amounts of RAM. quarantine_remove_cache() needs to scan whole
> quarantine in order to take out all objects belonging to the cache.
> Quarantine is currently 1/32-th of RAM, e.g. on a machine with 256GB
> of memory that will be 8GB. Moreover quarantine scanning is a walk
> over uncached linked list, which is slow.
> 
> Add cond_resched() after scanning of each non-empty batch of objects.
> Batches are specifically kept of reasonable size for quarantine_put().
> On a machine with 256GB of RAM we should have ~512 non-empty batches,
> each with 16MB of objects.

I'll add cc:stable to this one - softlockup reports on large machines
is a pretty significant issue.

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