From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161840AbcA0Vpx (ORCPT ); Wed, 27 Jan 2016 16:45:53 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:42820 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965358AbcA0Uh1 (ORCPT ); Wed, 27 Jan 2016 15:37:27 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Stefan Bader , Kent Overstreet , Jens Axboe , Kamal Mostafa Subject: [PATCH 4.2.y-ckt 075/268] bcache: prevent crash on changing writeback_running Date: Wed, 27 Jan 2016 12:32:16 -0800 Message-Id: <1453926929-17663-76-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1453926929-17663-1-git-send-email-kamal@canonical.com> References: <1453926929-17663-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 4.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.2.8-ckt3 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Stefan Bader commit 8d16ce540c94c9d366eb36fc91b7154d92d6397b upstream. Added a safeguard in the shutdown case. At least while not being attached it is also possible to trigger a kernel bug by writing into writeback_running. This change adds the same check before trying to wake up the thread for that case. Signed-off-by: Stefan Bader Cc: Kent Overstreet Signed-off-by: Jens Axboe Signed-off-by: Kamal Mostafa --- drivers/md/bcache/writeback.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h index 0a9dab1..073a042 100644 --- a/drivers/md/bcache/writeback.h +++ b/drivers/md/bcache/writeback.h @@ -63,7 +63,8 @@ static inline bool should_writeback(struct cached_dev *dc, struct bio *bio, static inline void bch_writeback_queue(struct cached_dev *dc) { - wake_up_process(dc->writeback_thread); + if (!IS_ERR_OR_NULL(dc->writeback_thread)) + wake_up_process(dc->writeback_thread); } static inline void bch_writeback_add(struct cached_dev *dc) -- 1.9.1