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

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Date:   Tue, 3 Mar 2020 10:58:29 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Cc:     stable@...r.kernel.org, Coly Li <colyli@...e.de>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 5.5 072/176] bcache: ignore pending signals when creating
 gc and allocator thread

On 3/3/20 10:42 AM, Greg Kroah-Hartman wrote:
> From: Coly Li <colyli@...e.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