WARNING in __btrfs_alloc_chunk (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e853993d29aa Linux 4.14.269
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12dd6559700000
kernel config: https://syzkaller.appspot.com/x/.config?x=cf48ea908f16e1e3
dashboard link: https://syzkaller.appspot.com/bug?extid=1bc032a1cfc410708b73
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1bc032...@syzkaller.appspotmail.com

BTRFS info (device loop4): disk space caching is enabled
BTRFS info (device loop4): has skinny extents
BTRFS info (device loop4): checking UUID tree
__btrfs_alloc_chunk: found more than 0 devices
------------[ cut here ]------------
WARNING: CPU: 1 PID: 22 at fs/btrfs/volumes.c:4726 __btrfs_alloc_chunk.cold+0x23/0x50 fs/btrfs/volumes.c:4726
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 22 Comm: kworker/u4:1 Not tainted 4.14.269-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound btrfs_async_reclaim_metadata_space
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x281 lib/dump_stack.c:58
panic+0x1f9/0x42d kernel/panic.c:183
__warn.cold+0x20/0x44 kernel/panic.c:547
report_bug+0x208/0x250 lib/bug.c:183
fixup_bug arch/x86/kernel/traps.c:177 [inline]
fixup_bug arch/x86/kernel/traps.c:172 [inline]
do_error_trap+0x195/0x2d0 arch/x86/kernel/traps.c:295
invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:964
RIP: 0010:__btrfs_alloc_chunk.cold+0x23/0x50 fs/btrfs/volumes.c:4726
RSP: 0018:ffff8880b560f9c0 EFLAGS: 00010286
RAX: 000000000000002e RBX: ffff8880a1f71240 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff878bbcc0 RDI: ffffed1016ac1f2e
RBP: dffffc0000000000 R08: 000000000000002e R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a2bbbae8
R13: 0000000001000000 R14: 00000000007e0000 R15: 0000000000720000
do_chunk_alloc+0x2fa/0x800 fs/btrfs/extent-tree.c:4707
flush_space+0x8d4/0xde0 fs/btrfs/extent-tree.c:5043
btrfs_async_reclaim_metadata_space+0x414/0xc20 fs/btrfs/extent-tree.c:5162
process_one_work+0x793/0x14a0 kernel/workqueue.c:2117
worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: e853993d29aa Linux 4.14.269
git tree: linux-4.14.y

console output: https://syzkaller.appspot.com/x/log.txt?x=165543f1700000

kernel config: https://syzkaller.appspot.com/x/.config?x=cf48ea908f16e1e3
dashboard link: https://syzkaller.appspot.com/bug?extid=1bc032a1cfc410708b73
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11354d21700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1bc032...@syzkaller.appspotmail.com

BTRFS info (device loop2): disk space caching is enabled
BTRFS info (device loop2): has skinny extents
BTRFS info (device loop2): checking UUID tree

__btrfs_alloc_chunk: found more than 0 devices
------------[ cut here ]------------
WARNING: CPU: 1 PID: 22 at fs/btrfs/volumes.c:4726 __btrfs_alloc_chunk.cold+0x23/0x50 fs/btrfs/volumes.c:4726
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 22 Comm: kworker/u4:1 Not tainted 4.14.269-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound btrfs_async_reclaim_metadata_space
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x281 lib/dump_stack.c:58
panic+0x1f9/0x42d kernel/panic.c:183
__warn.cold+0x20/0x44 kernel/panic.c:547
report_bug+0x208/0x250 lib/bug.c:183
fixup_bug arch/x86/kernel/traps.c:177 [inline]
fixup_bug arch/x86/kernel/traps.c:172 [inline]
do_error_trap+0x195/0x2d0 arch/x86/kernel/traps.c:295
invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:964
RIP: 0010:__btrfs_alloc_chunk.cold+0x23/0x50 fs/btrfs/volumes.c:4726
RSP: 0018:ffff8880b560f9c0 EFLAGS: 00010286

RAX: 000000000000002e RBX: ffff88809fd0a940 RCX: 0000000000000000

RDX: 0000000000000000 RSI: ffffffff878bbcc0 RDI: ffffed1016ac1f2e
RBP: dffffc0000000000 R08: 000000000000002e R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a19fd3a8