From: Jeff Moyer <jmoyer@redhat.com>
To: Lukas Czerner <lczerner@redhat.com>
Cc: linux-kernel@vger.kernel.org, axboe@kernel.dk,
linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org
Subject: Re: [PATCH v3] loop: Limit the number of requests in the bio list
Date: Tue, 13 Nov 2012 11:35:07 -0500 [thread overview]
Message-ID: <x49y5i5cvgk.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <1352824065-6734-1-git-send-email-lczerner@redhat.com> (Lukas Czerner's message of "Tue, 13 Nov 2012 17:27:45 +0100")
Lukas Czerner <lczerner@redhat.com> writes:
> Currently there is not limitation of number of requests in the loop bio
> list. This can lead into some nasty situations when the caller spawns
> tons of bio requests taking huge amount of memory. This is even more
> obvious with discard where blkdev_issue_discard() will submit all bios
> for the range and wait for them to finish afterwards. On really big loop
> devices and slow backing file system this can lead to OOM situation as
> reported by Dave Chinner.
>
> With this patch we will wait in loop_make_request() if the number of
> bios in the loop bio list would exceed 'nr_congestion_on'.
> We'll wake up the process as we process the bios form the list. Some
> threshold hysteresis is in place to avoid high frequency oscillation.
>
> Signed-off-by: Lukas Czerner <lczerner@redhat.com>
> Reported-by: Dave Chinner <dchinner@redhat.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
next prev parent reply other threads:[~2012-11-13 16:35 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-13 16:27 [PATCH v3] loop: Limit the number of requests in the bio list Lukas Czerner
2012-11-13 16:35 ` Jeff Moyer [this message]
2012-11-13 16:42 ` Jens Axboe
2012-11-14 9:02 ` Lukáš Czerner
2012-11-14 15:21 ` Jens Axboe
2012-11-15 8:20 ` Lukáš Czerner
2012-11-15 14:05 ` Jens Axboe
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