Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937880AbdCJO1A (ORCPT ); Fri, 10 Mar 2017 09:27:00 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:42645 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933707AbdCJLvJ (ORCPT ); Fri, 10 Mar 2017 06:51:09 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Konstantin Khlebnikov" , "Shaohua Li" , "Neil Brown" , "Shaohua Li" Date: Fri, 10 Mar 2017 11:46:22 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 058/370] md/raid5: limit request size according to implementation limits In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1829 Lines: 49 3.16.42-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Konstantin Khlebnikov commit e8d7c33232e5fdfa761c3416539bc5b4acd12db5 upstream. Current implementation employ 16bit counter of active stripes in lower bits of bio->bi_phys_segments. If request is big enough to overflow this counter bio will be completed and freed too early. Fortunately this not happens in default configuration because several other limits prevent that: stripe_cache_size * nr_disks effectively limits count of active stripes. And small max_sectors_kb at lower disks prevent that during normal read/write operations. Overflow easily happens in discard if it's enabled by module parameter "devices_handle_discard_safely" and stripe_cache_size is set big enough. This patch limits requests size with 256Mb - 8Kb to prevent overflows. Signed-off-by: Konstantin Khlebnikov Cc: Shaohua Li Cc: Neil Brown Signed-off-by: Shaohua Li Signed-off-by: Ben Hutchings --- drivers/md/raid5.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -6222,6 +6222,15 @@ static int run(struct mddev *mddev) stripe = (stripe | (stripe-1)) + 1; mddev->queue->limits.discard_alignment = stripe; mddev->queue->limits.discard_granularity = stripe; + + /* + * We use 16-bit counter of active stripes in bi_phys_segments + * (minus one for over-loaded initialization) + */ + blk_queue_max_hw_sectors(mddev->queue, 0xfffe * STRIPE_SECTORS); + blk_queue_max_discard_sectors(mddev->queue, + 0xfffe * STRIPE_SECTORS); + /* * unaligned part of discard request will be ignored, so can't * guarantee discard_zeroes_data