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Subject: Re: [PATCH 5.4 062/152] bcache: ignore pending signals when creating
 gc and allocator thread
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Coly Li <colyli@suse.de>, Sasha Levin <sashal@kernel.org>
References: <20200303174302.523080016@linuxfoundation.org>
 <20200303174309.501274295@linuxfoundation.org>
 <db776832-64ff-6757-de09-ced1ea8b368f@kernel.dk>
 <20200303181228.GA1014382@kroah.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <950f1d0a-6b01-6c80-8627-b1a9b2d2c89b@kernel.dk>
Date:   Tue, 3 Mar 2020 11:19:28 -0700
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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