From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2A1FFFA372C for ; Fri, 8 Nov 2019 11:53:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0ABA621D6C for ; Fri, 8 Nov 2019 11:53:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389905AbfKHLxg (ORCPT ); Fri, 8 Nov 2019 06:53:36 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:56883 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391394AbfKHLqj (ORCPT ); Fri, 8 Nov 2019 06:46:39 -0500 Received: from fsav110.sakura.ne.jp (fsav110.sakura.ne.jp [27.133.134.237]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id xA8BfQTc062503; Fri, 8 Nov 2019 20:41:26 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav110.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav110.sakura.ne.jp); Fri, 08 Nov 2019 20:41:26 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav110.sakura.ne.jp) Received: from [192.168.1.9] (softbank126227191088.bbtec.net [126.227.191.88]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id xA8BfKEh062452 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NO); Fri, 8 Nov 2019 20:41:26 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: [PATCH] block: Bail out iteration functions upon SIGKILL. To: Bob Liu , axboe@kernel.dk Cc: linux-block@vger.kernel.org References: <000000000000c52dbf05958f3f3a@google.com> <3fbc4bb2-a03b-fbfa-4803-47a6d0075ff2@I-love.SAKURA.ne.jp> <24296ff7-4a5f-2bd9-63c7-07831f7b4d8d@oracle.com> From: Tetsuo Handa Message-ID: <8fde32da-d5e5-11b7-9ed7-e3aa5b003647@i-love.sakura.ne.jp> Date: Fri, 8 Nov 2019 20:41:22 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <24296ff7-4a5f-2bd9-63c7-07831f7b4d8d@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org syzbot found that a thread can stall for minutes inside fallocate() after that thread was killed by SIGKILL [1]. While trying to allocate 64TB of disk space using fallocate() is legal, delaying termination of killed thread for minutes is bad. Thus, allow iteration functions in block/blk-lib.c to be killable. [1] https://syzkaller.appspot.com/bug?id=9386d051e11e09973d5a4cf79af5e8cedf79386d Signed-off-by: Tetsuo Handa Reported-by: syzbot --- block/blk-lib.c | 44 ++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 40 insertions(+), 4 deletions(-) diff --git a/block/blk-lib.c b/block/blk-lib.c index 5f2c429..6ca7cae 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -7,9 +7,22 @@ #include #include #include +#include #include "blk.h" +static int blk_should_abort(struct bio *bio) +{ + int ret; + + cond_resched(); + if (!fatal_signal_pending(current)) + return 0; + ret = submit_bio_wait(bio); + bio_put(bio); + return ret ? ret : -EINTR; +} + struct bio *blk_next_bio(struct bio *bio, unsigned int nr_pages, gfp_t gfp) { struct bio *new = bio_alloc(gfp, nr_pages); @@ -55,6 +68,7 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, return -EINVAL; while (nr_sects) { + int ret; sector_t req_sects = min_t(sector_t, nr_sects, bio_allowed_max_sectors(q)); @@ -75,7 +89,11 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, * us to schedule out to avoid softlocking if preempt * is disabled. */ - cond_resched(); + ret = blk_should_abort(bio); + if (ret) { + *biop = NULL; + return ret; + } } *biop = bio; @@ -154,6 +172,8 @@ static int __blkdev_issue_write_same(struct block_device *bdev, sector_t sector, max_write_same_sectors = bio_allowed_max_sectors(q); while (nr_sects) { + int ret; + bio = blk_next_bio(bio, 1, gfp_mask); bio->bi_iter.bi_sector = sector; bio_set_dev(bio, bdev); @@ -171,7 +191,11 @@ static int __blkdev_issue_write_same(struct block_device *bdev, sector_t sector, bio->bi_iter.bi_size = nr_sects << 9; nr_sects = 0; } - cond_resched(); + ret = blk_should_abort(bio); + if (ret) { + *biop = NULL; + return ret; + } } *biop = bio; @@ -230,6 +254,8 @@ static int __blkdev_issue_write_zeroes(struct block_device *bdev, return -EOPNOTSUPP; while (nr_sects) { + int ret; + bio = blk_next_bio(bio, 0, gfp_mask); bio->bi_iter.bi_sector = sector; bio_set_dev(bio, bdev); @@ -245,7 +271,11 @@ static int __blkdev_issue_write_zeroes(struct block_device *bdev, bio->bi_iter.bi_size = nr_sects << 9; nr_sects = 0; } - cond_resched(); + ret = blk_should_abort(bio); + if (ret) { + *biop = NULL; + return ret; + } } *biop = bio; @@ -281,6 +311,8 @@ static int __blkdev_issue_zero_pages(struct block_device *bdev, return -EPERM; while (nr_sects != 0) { + int ret; + bio = blk_next_bio(bio, __blkdev_sectors_to_bio_pages(nr_sects), gfp_mask); bio->bi_iter.bi_sector = sector; @@ -295,7 +327,11 @@ static int __blkdev_issue_zero_pages(struct block_device *bdev, if (bi_size < sz) break; } - cond_resched(); + ret = blk_should_abort(bio); + if (ret) { + *biop = NULL; + return ret; + } } *biop = bio; -- 1.8.3.1