linux-kernel - Re: [PATCH 2/2 v6] loop: Limit the number of requests in the bio list

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <x49txs7p518.fsf@segfault.boston.devel.redhat.com>
Date:	Fri, 30 Nov 2012 08:57:23 -0500
From:	Jeff Moyer <jmoyer@...hat.com>
To:	Lukas Czerner <lczerner@...hat.com>
Cc:	linux-kernel@...r.kernel.org, linux-raid@...r.kernel.org,
	axboe@...nel.dk, akpm@...ux-foundation.org
Subject: Re: [PATCH 2/2 v6] loop: Limit the number of requests in the bio list

Lukas Czerner <lczerner@...hat.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@...hat.com>
> Reported-by: Dave Chinner <dchinner@...hat.com>

Lukas, please carry forward acked-by tags when there is no change so I
don't have to keep acking.

Thanks,
Jeff

Acked-by: Jeff Moyer <jmoyer@...hat.com>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/