WARNING in __writeback_inodes_sb

WARNING in __writeback_inodes_sb_nr
Status: upstream: reported C repro on 2020/09/20 14:27
Reported-by: syzbot+5c2dc141988585eb49ce@syzkaller.appspotmail.com
First crash: 66d, last: 26d

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	WARNING in __writeback_inodes_sb_nr	syz	done		2	19d	42d	0/17	upstream: reported syz repro on 2020/10/14 12:01

Sample crash report:

BTRFS info (device loop0): turning on flush-on-commit
BTRFS info (device loop0): disk space caching is enabled
BTRFS info (device loop0): has skinny extents
BTRFS info (device loop0): checking UUID tree
------------[ cut here ]------------
WARNING: CPU: 1 PID: 6514 at fs/fs-writeback.c:2394 __writeback_inodes_sb_nr.cold+0x11/0x18 fs/fs-writeback.c:2394
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 6514 Comm: btrfs-transacti Not tainted 4.19.149-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x22c/0x33e lib/dump_stack.c:118
 panic+0x2ac/0x565 kernel/panic.c:186
 __warn.cold+0x20/0x5a kernel/panic.c:541
 report_bug+0x262/0x2b0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 fixup_bug arch/x86/kernel/traps.c:173 [inline]
 do_error_trap+0x1e1/0x330 arch/x86/kernel/traps.c:296
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1038
RIP: 0010:__writeback_inodes_sb_nr.cold+0x11/0x18 fs/fs-writeback.c:2394
Code: 09 c1 af ff 41 0f b6 f5 48 c7 c7 00 f9 94 89 e8 89 11 f4 01 e9 e3 7b ff ff e8 ef c0 af ff 48 c7 c7 e0 5d 16 88 e8 92 3c 99 ff <0f> 0b e9 9a 80 ff ff e8 d7 c0 af ff 0f b6 f3 48 c7 c7 80 f9 94 89
RSP: 0018:ffff8880a49ffc48 EFLAGS: 00010286
RAX: 0000000000000024 RBX: 1ffff1101493ff8b RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815b623f RDI: ffffed101493ff7b
RBP: ffff8880a4d10880 R08: 0000000000000024 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: 0000000000006400
R13: ffff8880a3f18240 R14: ffff8880a4d109b0 R15: ffff8880a49ffc88
 btrfs_start_delalloc_flush fs/btrfs/transaction.c:1924 [inline]
 btrfs_commit_transaction+0x1bb1/0x24a0 fs/btrfs/transaction.c:2075
 transaction_kthread+0x385/0x483 fs/btrfs/disk-io.c:1794
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (8):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Maintainers
ci2-linux-4-19	2020/10/02 11:10	linux-4.19.y	b09c3451	9602ddf4	.config	log	report	syz	C		linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-19	2020/09/20 17:13	linux-4.19.y	015e94d0	9564d2e9	.config	log	report	syz	C		linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-19	2020/10/30 12:48	linux-4.19.y	f5d8eef0	a6e3ac3b	.config	log	report			info	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-19	2020/10/01 05:34	linux-4.19.y	10ad6cfd	a9767fb2	.config	log	report			info	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-19	2020/09/30 11:11	linux-4.19.y	10ad6cfd	8516f6d3	.config	log	report			info	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-19	2020/09/30 09:50	linux-4.19.y	10ad6cfd	8516f6d3	.config	log	report			info	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-19	2020/09/20 20:02	linux-4.19.y	015e94d0	9564d2e9	.config	log	report			info	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-19	2020/09/20 14:26	linux-4.19.y	015e94d0	9564d2e9	.config	log	report			info	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk