bisecting fixing commit since 3c8c23092588a23bf1856a64f58c37f477a413be
building syzkaller on 8bdd5343e64460868dd1318257a39f1e7fd89471
testing commit 3c8c23092588a23bf1856a64f58c37f477a413be with gcc (GCC) 8.4.1 20210217
kernel signature: 7ee9be4859f6550aafe80f79a94d553be7107665a225b7f461f3bc8ab6d92302
all runs: crashed: WARNING in __writeback_inodes_sb_nr
testing current HEAD 9a2dc0e6c531d595bcdf2c66d0be131679bd02df
testing commit 9a2dc0e6c531d595bcdf2c66d0be131679bd02df with gcc (GCC) 8.4.1 20210217
kernel signature: 351a807d42e63a5da357a4cc2c261e26a50ee1fc7a0e07e87578e5c3ad218a88
all runs: crashed: WARNING in __writeback_inodes_sb_nr
revisions tested: 2, total time: 23m50.918351224s (build: 16m40.328009267s, test: 6m47.392239096s)
the crash still happens on HEAD
commit msg: Linux 4.19.194
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/loop2 devid 1 generation 7 scanned by systemd-udevd (9887)
------------[ cut here ]------------
IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
WARNING: CPU: 0 PID: 9976 at fs/fs-writeback.c:2390 __writeback_inodes_sb_nr.cold.14+0xc/0x13 fs/fs-writeback.c:2390
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 9976 Comm: btrfs-transacti Not tainted 4.19.194-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
ieee80211 phy14: Selected rate control algorithm 'minstrel_ht'
 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.14+0xc/0x13 fs/fs-writeback.c:2390
Code: 09 ff ff ff e8 9f 7f 08 fa eb bb 48 c7 c7 60 d9 13 88 e8 23 ff fe ff 0f 0b e9 ca da 1b fa 48 c7 c7 60 d9 13 88 e8 10 ff fe ff <0f> 0b e9 9d 01 1c fa 48 c7 c7 60 d9 13 88 e8 fd fe fe ff 0f 0b e9
RSP: 0018:ffff888091da7c38 EFLAGS: 00010282
RAX: 0000000000000024 RBX: 1ffff110123b4f89 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff88502040 RDI: ffffffff8bad8720
RBP: ffff888091da7d30 R08: ffffed1017444e99 R09: ffffed1017444e98
R10: ffffed1017444e98 R11: ffff8880ba2274c7 R12: ffff8880ac2ce400
R13: ffff888099a36330 R14: ffff888091da7c68 R15: ffff888099a36200
 writeback_inodes_sb_nr fs/fs-writeback.c:2410 [inline]
 writeback_inodes_sb+0x22/0x30 fs/fs-writeback.c:2425
 btrfs_start_delalloc_flush fs/btrfs/transaction.c:1925 [inline]
 btrfs_commit_transaction+0x1974/0x2330 fs/btrfs/transaction.c:2076
IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
 transaction_kthread+0x2a2/0x380 fs/btrfs/disk-io.c:1794
 kthread+0x347/0x410 kernel/kthread.c:259
wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Kernel Offset: disabled
Rebooting in 86400 seconds..