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([2405:4802:1d4a:e90:3a0c:2ea9:4ab7:bd1b]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2df91460aaasm26296305ad.73.2026.09.26.22.15.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 26 Sep 2026 22:15:34 -0700 (PDT) From: Nguyen Ngoc Thang To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, "Darrick J . Wong" , Bart Van Assche , Hannes Reinecke , Nguyen Ngoc Thang , syzbot+afa7aef0c237038586e7@syzkaller.appspotmail.com, stable@vger.kernel.org Subject: [PATCH] block: make blkdev_fallocate() zeroout killable Date: Sun, 27 Sep 2026 12:15:28 +0700 Message-ID: <20260927051528.34698-1-ngocthang2710.1999@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit blkdev_fallocate() zeroes the requested range while holding i_rwsem and invalidate_lock exclusively, but does not pass BLKDEV_ZERO_KILLABLE to blkdev_issue_zeroout(). On a large device that falls back to writing zero pages (e.g. null_blk), the loop keeps going after the caller received SIGKILL, and every buffered reader of the device blocks behind it: rwsem_down_read_slowpath+0x61e/0x920 kernel/locking/rwsem.c:1086 down_read+0x99/0x2e0 kernel/locking/rwsem.c:1539 blkdev_read_iter+0x2f8/0x440 block/fops.c:854 syzbot reports this as a hung task. BLKZEROOUT already sets the flag for the same reason; do the same for fallocate. Reported-by: syzbot+afa7aef0c237038586e7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=afa7aef0c237038586e7 Fixes: 25f4c41415e5 ("block: implement (some of) fallocate for block devices") Cc: stable@vger.kernel.org Signed-off-by: Nguyen Ngoc Thang --- block/fops.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/block/fops.c b/block/fops.c index 2ce7c6c4714e..a2fe27d8ceff 100644 --- a/block/fops.c +++ b/block/fops.c @@ -909,7 +909,8 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start, goto fail; error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT, - len >> SECTOR_SHIFT, GFP_KERNEL, flags); + len >> SECTOR_SHIFT, GFP_KERNEL, + flags | BLKDEV_ZERO_KILLABLE); fail: filemap_invalidate_unlock(inode->i_mapping); inode_unlock(inode); -- 2.43.0