From patchwork Fri May 6 20:45:12 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Valente X-Patchwork-Id: 67307 Delivered-To: patch@linaro.org Received: by 10.140.92.199 with SMTP id b65csp523799qge; Fri, 6 May 2016 14:21:15 -0700 (PDT) X-Received: by 10.98.34.72 with SMTP id i69mr31680133pfi.153.1462569675623; Fri, 06 May 2016 14:21:15 -0700 (PDT) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id fn8si20400042pab.197.2016.05.06.14.21.15; Fri, 06 May 2016 14:21:15 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758719AbcEFVVN (ORCPT + 29 others); Fri, 6 May 2016 17:21:13 -0400 Received: from spostino.sms.unimo.it ([155.185.44.3]:60636 "EHLO spostino.sms.unimo.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756722AbcEFVVL (ORCPT ); Fri, 6 May 2016 17:21:11 -0400 X-Greylist: delayed 2125 seconds by postgrey-1.27 at vger.kernel.org; Fri, 06 May 2016 17:21:10 EDT Received: from [185.14.9.51] (port=50957 helo=localhost.localdomain) by spostino.sms.unimo.it with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA256:128) (Exim 4.80) (envelope-from ) id 1aymd1-0004cx-Pn; Fri, 06 May 2016 22:45:40 +0200 From: Paolo Valente To: Jens Axboe , Tejun Heo Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ulf.hansson@linaro.org, linus.walleij@linaro.org, broonie@kernel.org, stable@vger.kernel.org, Paolo Valente Subject: [PATCH BUGFIX] block: add missing group association in bio_split Date: Fri, 6 May 2016 22:45:12 +0200 Message-Id: <1462567512-3007-1-git-send-email-paolo.valente@linaro.org> X-Mailer: git-send-email 1.9.1 UNIMORE-X-SA-Score: -2.9 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When a bio is split, the newly created bio must be associated with the same blkcg as the original bio (if BLK_CGROUP is enabled). If this operation is not performed, then the new bio is not associated with any group, and the group of the current task is returned when the group of the bio is requested. Depending on the frequency of splits, this may cause a large percentage of the bios belonging to a given group to be treated as if belonging to other groups (in most cases as if belonging to the root group). The expected group isolation may thereby be then broken. This commit adds the missing association in bio_split. Signed-off-by: Paolo Valente --- block/bio.c | 5 +++++ 1 file changed, 5 insertions(+) -- 1.9.1 diff --git a/block/bio.c b/block/bio.c index 807d25e..c4a3834 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1811,6 +1811,11 @@ struct bio *bio_split(struct bio *bio, int sectors, bio_advance(bio, split->bi_iter.bi_size); +#ifdef CONFIG_BLK_CGROUP + if (bio->bi_css) + bio_associate_blkcg(split, bio->bi_css); +#endif + return split; } EXPORT_SYMBOL(bio_split);