bisecting fixing commit since 3c8c23092588a23bf1856a64f58c37f477a413be
building syzkaller on 8bdd5343e64460868dd1318257a39f1e7fd89471
testing commit 3c8c23092588a23bf1856a64f58c37f477a413be
compiler: gcc version 8.4.1 20210217 (GCC)
kernel signature: 2403759721cc3b81b5e48e591cf690c051c38cae5eab0e14cbc68567f2958dc5
all runs: crashed: WARNING in __writeback_inodes_sb_nr
testing current HEAD 4938296e03bd227e5020d63d418956fe52baf97c
testing commit 4938296e03bd227e5020d63d418956fe52baf97c
compiler: gcc version 8.4.1 20210217 (GCC)
kernel signature: 74acf568350c69c0f2fd7ddc31d0f9d76d8954a533ae3472f30f8a00cc9ca00a
all runs: crashed: WARNING in __writeback_inodes_sb_nr
revisions tested: 2, total time: 28m2.905500416s (build: 20m49.162316969s, test: 6m38.206700799s)
the crash still happens on HEAD
commit msg: Linux 4.19.198
crash: WARNING in __writeback_inodes_sb_nr
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
------------[ cut here ]------------
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready
WARNING: CPU: 0 PID: 9858 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: 9858 Comm: btrfs-transacti Not tainted 4.19.198-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 96 3e 08 fa eb e2 48 c7 c7 c0 d9 13 88 e8 c1 00 ff ff 0f 0b e9 f1 9b 1b fa 48 c7 c7 c0 d9 13 88 e8 ae 00 ff ff <0f> 0b e9 c4 c2 1b fa 48 c7 c7 c0 d9 13 88 e8 9b 00 ff ff 0f 0b e9
RSP: 0018:ffff88809c1efc38 EFLAGS: 00010282
RAX: 0000000000000024 RBX: 1ffff1101383df89 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff88502140 RDI: ffffffff8bada720
RBP: ffff88809c1efd30 R08: ffffed1017444e99 R09: ffffed1017444e98
R10: ffffed1017444e98 R11: ffff8880ba2274c7 R12: ffff888098027240
R13: ffff88809e9c4b30 R14: ffff88809c1efc68 R15: ffff88809e9c4a00
 writeback_inodes_sb_nr fs/fs-writeback.c:2390 [inline]
 writeback_inodes_sb+0x22/0x30 fs/fs-writeback.c:2405
batman_adv: batadv0: Interface activated: batadv_slave_1
 btrfs_start_delalloc_flush fs/btrfs/transaction.c:1927 [inline]
 btrfs_commit_transaction+0x1974/0x2330 fs/btrfs/transaction.c:2078
IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
ieee80211 phy7: Selected rate control algorithm 'minstrel_ht'
 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..