Re: [PATCH 5.4 062/152] bcache: ignore pending signals when creating gc and allocator thread

Jens Axboe
2020-03-03T18:19:33Z

On 3/3/20 11:12 AM, Greg Kroah-Hartman wrote:
> On Tue, Mar 03, 2020 at 10:55:04AM -0700, Jens Axboe wrote:
>> 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.
>>
>> Please drop this one, it's being reverted in mainline.
>
> Dropped from all trees now, thanks.

Thanks!

--
Jens Axboe