From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZpA7hkVgcPMpnLCZrXLNXN/uXLFPnjrG+efO586phkJLwKppRBgBUa4TlgSXhYwfyiwU4HH ARC-Seal: i=1; a=rsa-sha256; t=1525270336; cv=none; d=google.com; s=arc-20160816; b=r+APWaEriqagsQyDFikVLUrCk34zpPlxwuOYzVx2PZ96Pyui/uMmT8bMRG+fLYXR2z sXyuUajyqRvWGL51/3hT7LIiojp3vz1REAjZ2saM6Bnuo6OS4uq1BQhlLu48V5fOq+u8 8GecN3SPH9zhbllpNrIE7BfHLMpWOk+MSQsBz6M9/6IvsptJ/y8sxpvY5WCIfog5L+hy zBxCWxB8ujWFxJVgtMEQM3K3QNeWuoJtlEGZ/8Mat0DbT7FsEWLE6K8MO8Nctr/e3vLj 9UJwhTmIuvX+hfZY4wCkGbklX096CCMdxMAGZsbsJ5W0NWGcoyKfYdw/Z4z2LFqbltL+ L5Fw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:content-language:in-reply-to:mime-version :user-agent:date:message-id:from:cc:references:to:subject :arc-authentication-results; bh=IO2Jnn2nDhprExMD7knXrduEpTBW1m0kn78EWbqn06c=; b=xD9pjqNO1HaXe0k6i18WJsqQ/iCgcxrO+XLUrVUUpavoEN+/eh71Lc1XXLQbRz9BqC Qoh1KGOqDC7GUvC1Uh9K6UxTYlmNVhWLvgcBQlCATYDWKbvNI5M5WBDTP8gNBlj6SOgk nlozvdLjU3SnSkJNr/C06Nctbr37foCE86Xi+RlSdYdXAlUHd87NaD0hbXzvbz3mvMkE /PbjsQgaF8cTTqbK8uBNWsxZpkNryle+QouE32KcrFiybt1qOtA9IqOneRtqwgl1EjjM lkviwDNx9oudnZjQuh3Spm+AMkl34mqVKkrskqZ+k1ZPZ7mvV4UyxJPp09zgf01EG33X lBcQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of penguin-kernel@i-love.sakura.ne.jp designates 202.181.97.72 as permitted sender) smtp.mailfrom=penguin-kernel@i-love.sakura.ne.jp Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of penguin-kernel@i-love.sakura.ne.jp designates 202.181.97.72 as permitted sender) smtp.mailfrom=penguin-kernel@i-love.sakura.ne.jp Subject: Re: WARNING in sysfs_remove_group To: syzbot , linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, Jens Axboe References: <001a113ed2fa7bedfe055c8316a5@google.com> <94eb2c030882b2b1b505610813df@google.com> Cc: dvyukov@google.com, gregkh@linuxfoundation.org From: Tetsuo Handa Message-ID: <55ff5960-eaab-5a36-5605-4e2230b77607@I-love.SAKURA.ne.jp> Date: Wed, 2 May 2018 23:11:59 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <94eb2c030882b2b1b505610813df@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1582398672104881968?= X-GMAIL-MSGID: =?utf-8?q?1599361868320682332?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: syzbot has hit this bug for nearly 6000 times. Why not to fix this trivial one? ;-) >>From 626d33de1b70b11ecaf95a9f83f7644998e54cbb Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Wed, 2 May 2018 23:03:48 +0900 Subject: [PATCH] loop: remember whether sysfs_create_group() succeeded syzbot is hitting WARN() triggered by memory allocation fault injection [1] because loop module is calling sysfs_remove_group() when sysfs_create_group() failed. Fix this by remembering whether sysfs_create_group() succeeded. [1] https://syzkaller.appspot.com/bug?id=3f86c0edf75c86d2633aeb9dd69eccc70bc7e90b Signed-off-by: Tetsuo Handa Reported-by: syzbot Cc: Jens Axboe --- drivers/block/loop.c | 11 ++++++----- drivers/block/loop.h | 1 + 2 files changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 5d4e316..1d758d8 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -809,16 +809,17 @@ static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf) .attrs= loop_attrs, }; -static int loop_sysfs_init(struct loop_device *lo) +static void loop_sysfs_init(struct loop_device *lo) { - return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj, - &loop_attribute_group); + lo->sysfs_ready = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj, + &loop_attribute_group); } static void loop_sysfs_exit(struct loop_device *lo) { - sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj, - &loop_attribute_group); + if (lo->sysfs_ready) + sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj, + &loop_attribute_group); } static void loop_config_discard(struct loop_device *lo) diff --git a/drivers/block/loop.h b/drivers/block/loop.h index b78de98..73c801f 100644 --- a/drivers/block/loop.h +++ b/drivers/block/loop.h @@ -58,6 +58,7 @@ struct loop_device { struct kthread_worker worker; struct task_struct *worker_task; bool use_dio; + bool sysfs_ready; struct request_queue *lo_queue; struct blk_mq_tag_set tag_set; -- 1.8.3.1