bisecting fixing commit since b09c34517e1ac4018e3bb75ed5c8610a8a1f486b
building syzkaller on 9602ddf403bdf3cfd87efef14becc76f9a38b81d
testing commit b09c34517e1ac4018e3bb75ed5c8610a8a1f486b with gcc (GCC) 8.1.0
kernel signature: 6a8aee043b7b3c59131fb21a98c4ef46bc47b4eb77b9e6a7db3ab13977516629
all runs: crashed: WARNING in __writeback_inodes_sb_nr
testing current HEAD 0c88e405c97ed1828443b67891e6d4bb6e56cd4e
testing commit 0c88e405c97ed1828443b67891e6d4bb6e56cd4e with gcc (GCC) 8.1.0
kernel signature: ad1cb6684f60d3b5abfb31adf325e31ad55552513a4dffbfe5e8a4dc4074ec2c
all runs: crashed: WARNING in __writeback_inodes_sb_nr
revisions tested: 2, total time: 25m44.502404298s (build: 19m33.221786781s, test: 5m32.432423928s)
the crash still happens on HEAD
commit msg: Linux 4.19.160
crash: WARNING in __writeback_inodes_sb_nr
BTRFS info (device loop1): turning on flush-on-commit
BTRFS info (device loop1): disk space caching is enabled
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): checking UUID tree
------------[ cut here ]------------
WARNING: CPU: 0 PID: 7674 at fs/fs-writeback.c:2394 __writeback_inodes_sb_nr.cold.14+0xc/0x13 fs/fs-writeback.c:2394
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 7674 Comm: btrfs-transacti Not tainted 4.19.160-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+0x17c/0x22a lib/dump_stack.c:118
 panic+0x1cd/0x375 kernel/panic.c:186
 __warn.cold.7+0x1b/0x3e kernel/panic.c:541
 report_bug+0x1a4/0x200 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x200/0x350 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1038
RIP: 0010:__writeback_inodes_sb_nr.cold.14+0xc/0x13 fs/fs-writeback.c:2394
Code: 09 ff ff ff e8 c4 66 ec ff eb bb 48 c7 c7 e0 f9 53 87 e8 16 f8 a8 ff 0f 0b e9 0f 7f ff ff 48 c7 c7 e0 f9 53 87 e8 03 f8 a8 ff <0f> 0b e9 02 a7 ff ff 48 c7 c7 e0 f9 53 87 e8 f0 f7 a8 ff 0f 0b e9
RSP: 0018:ffff8881d9327c38 EFLAGS: 00010282
RAX: 0000000000000024 RBX: 1ffff1103b264f89 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff878b5960 RDI: ffffffff8a3e1a60
RBP: ffff8881d9327d30 R08: ffffed103ecc5081 R09: ffffed103ecc5080
R10: ffffed103ecc5080 R11: ffff8881f6628407 R12: ffff8881e93734c0
R13: ffff8881e8ede270 R14: ffff8881d9327c68 R15: ffff8881e8ede140
 writeback_inodes_sb_nr fs/fs-writeback.c:2414 [inline]
 writeback_inodes_sb+0x22/0x30 fs/fs-writeback.c:2429
 btrfs_start_delalloc_flush fs/btrfs/transaction.c:1924 [inline]
 btrfs_commit_transaction+0x1974/0x2330 fs/btrfs/transaction.c:2075
 transaction_kthread+0x2a2/0x380 fs/btrfs/disk-io.c:1794
 kthread+0x347/0x410 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Kernel Offset: disabled
Rebooting in 86400 seconds..