WARNING: lock held when returning to user space in ovl_write

WARNING: lock held when returning to user space in ovl_write_iter

Status: fixed on 2020/04/15 17:19
Subsystems: overlayfs
[Documentation on labels]
Reported-by: syzbot+9331a354f4f624a52a55@syzkaller.appspotmail.com
Fix commit: c853680453ac ovl: fix lockdep warning for async write
First crash: 1796d, last: 1779d

Cause bisection: introduced by (bisect log) :
commit 2406a307ac7ddfd7effeeaff6947149ec6a95b4e
Author: Jiufei Xue <jiufei.xue@linux.alibaba.com>
Date: Wed Nov 20 09:45:26 2019 +0000

ovl: implement async IO routines

Crash: WARNING: lock held when returning to user space in ovl_write_iter (log)
Repro: C syz .config

▶ ▼ Discussions (1)

Title	Replies (including bot)	Last reply
WARNING: lock held when returning to user space in ovl_write_iter	2 (4)	2020/03/13 08:53

▶ ▼ Last patch testing requests (2)


Created	Duration	User	Patch	Repo	Result
2020/03/13 08:53	18m	miklos@szeredi.hu	patch	git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 63623fd4	OK
2020/03/12 15:30	19m	miklos@szeredi.hu	patch	git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 63623fd4	OK

Sample crash report:

================================================
WARNING: lock held when returning to user space!
5.6.0-rc3-syzkaller #0 Not tainted
------------------------------------------------
syz-executor005/10349 is leaving the kernel with locks still held!
1 lock held by syz-executor005/10349:
 #0: ffff888214fd6428 (sb_writers#4){.+.+}, at: file_start_write include/linux/fs.h:2903 [inline]
 #0: ffff888214fd6428 (sb_writers#4){.+.+}, at: ovl_write_iter+0xcc1/0x1090 fs/overlayfs/file.c:348

Crashes (6):
Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Manager
2020/03/05 06:14	upstream	63623fd44972	c88c7b75	.config	console log	report	syz	C	ci-upstream-kasan-gce-selinux-root
2020/03/03 18:19	upstream	63623fd44972	c88c7b75	.config	console log	report	syz	C	ci-upstream-kasan-gce-root
2020/03/01 09:35	upstream	63623fd44972	c88c7b75	.config	console log	report	syz	C	ci-upstream-kasan-gce-smack-root
2020/03/16 18:14	linux-next	770fbb32d34e	749688d2	.config	console log	report	syz	C	ci-upstream-linux-next-kasan-gce-root
2020/02/28 07:17	linux-next	bdc5461b23ca	59b57593	.config	console log	report	syz	C	ci-upstream-linux-next-kasan-gce-root
2020/02/28 06:30	linux-next	bdc5461b23ca	59b57593	.config	console log	report			ci-upstream-linux-next-kasan-gce-root

* ~~Struck through~~ repros no longer work on HEAD.