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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>,
        linux-kernel@vger.kernel.org
Cc:     stable@vger.kernel.org, Coly Li <colyli@suse.de>,
        Sasha Levin <sashal@kernel.org>
References: <20200303174302.523080016@linuxfoundation.org>
 <20200303174309.501274295@linuxfoundation.org>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <db776832-64ff-6757-de09-ced1ea8b368f@kernel.dk>
Date:   Tue, 3 Mar 2020 10:55:04 -0700
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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.

-- 
Jens Axboe