Re: [PATCH 5.5 072/176] bcache: ignore pending signals when creating gc and allocator thread

Jens Axboe
2020-03-03T18:05:17Z

On 3/3/20 10:42 AM, Greg Kroah-Hartman wrote:
> From: Coly Li <colyli@suse.de>
>
> [ Upstream commit 0b96da639a4874311e9b5156405f69ef9fc3bef8 ]
>
> When run a cache set, all the bcache btree node of this cache set will
> be checked by bch_btree_check(). If the bcache btree is very large,
> iterating all the btree nodes will occupy too much system memory and
> the bcache registering process might be selected and killed by system
> OOM killer. kthread_run() will fail if current process has pending
> signal, therefore the kthread creating in run_cache_set() for gc and
> allocator kernel threads are very probably failed for a very large
> bcache btree.
>
> Indeed such OOM is safe and the registering process will exit after
> the registration done. Therefore this patch flushes pending signals
> during the cache set start up, specificly in bch_cache_allocator_start()
> and bch_gc_thread_start(), to make sure run_cache_set() won't fail for
> large cahced data set.

Ditto this one, of course.

Did someone send this in for stable? It's not marked stable in the
original commit.

--
Jens Axboe