bisecting fixing commit since 3c8c23092588a23bf1856a64f58c37f477a413be
building syzkaller on 8bdd5343e64460868dd1318257a39f1e7fd89471
testing commit 3c8c23092588a23bf1856a64f58c37f477a413be
compiler: gcc version 8.4.1 20210217 (GCC)
kernel signature: 18b38a682ed8febac03d4e864285038ef7bd2c941efdde06eecc9124e346b714
all runs: crashed: WARNING in __writeback_inodes_sb_nr
testing current HEAD 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1
testing commit 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1
compiler: gcc version 8.4.1 20210217 (GCC)
kernel signature: 8ea1fe104979038c44d9ab1de55f9bc26facd0cd12bdf76cc3102fb27e439db7
all runs: crashed: WARNING in __writeback_inodes_sb_nr
revisions tested: 2, total time: 26m13.472263419s (build: 19m10.44136434s, test: 6m35.545290914s)
the crash still happens on HEAD
commit msg: Linux 4.19.204
crash: WARNING in __writeback_inodes_sb_nr
wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
BTRFS warning (device <unknown>): duplicate device /dev/loop4 devid 1 generation 7 scanned by systemd-udevd (9911)
------------[ cut here ]------------
IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
WARNING: CPU: 0 PID: 9958 at fs/fs-writeback.c:2370 __writeback_inodes_sb_nr.cold.13+0xc/0x13 fs/fs-writeback.c:2370
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 9958 Comm: btrfs-transacti Not tainted 4.19.204-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/0x226 lib/dump_stack.c:118
 panic+0x1cd/0x375 kernel/panic.c:186
 __warn.cold.7+0x1b/0x36 kernel/panic.c:541
 report_bug+0x1a1/0x200 lib/bug.c:183
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 fixup_bug arch/x86/kernel/traps.c:173 [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.13+0xc/0x13 fs/fs-writeback.c:2370
Code: ae 48 89 df e8 02 20 08 fa eb e2 48 c7 c7 c0 da 13 88 e8 c1 00 ff ff 0f 0b e9 6d 60 1b fa 48 c7 c7 c0 da 13 88 e8 ae 00 ff ff <0f> 0b e9 40 87 1b fa 48 c7 c7 c0 da 13 88 e8 9b 00 ff ff 0f 0b e9
RSP: 0018:ffff888091da7c38 EFLAGS: 00010282
RAX: 0000000000000024 RBX: 1ffff110123b4f89 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff88502360 RDI: ffffffff8bada720
RBP: ffff888091da7d30 R08: ffffed1017444e99 R09: ffffed1017444e98
R10: ffffed1017444e98 R11: ffff8880ba2274c7 R12: ffff8880b4d99500
R13: ffff8880b52d86f0 R14: ffff888091da7c68 R15: ffff8880b52d85c0
 writeback_inodes_sb_nr fs/fs-writeback.c:2390 [inline]
 writeback_inodes_sb+0x22/0x30 fs/fs-writeback.c:2405
 btrfs_start_delalloc_flush fs/btrfs/transaction.c:1927 [inline]
 btrfs_commit_transaction+0x1974/0x2330 fs/btrfs/transaction.c:2078
 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..