bisecting fixing commit since 0c88e405c97ed1828443b67891e6d4bb6e56cd4e
building syzkaller on 1a1f4bd8c48f86af4bc94a2e3a86fc0de9c52c93
testing commit 0c88e405c97ed1828443b67891e6d4bb6e56cd4e with gcc (GCC) 8.4.1 20210217
kernel signature: 68ae5c9f36c5c496e7f48c94e00fb64293126ddf34226e5ab0477e3838e08336
run #0: crashed: kernel BUG in submit_bh_wbc
run #1: crashed: general protection fault in bdevname
run #2: crashed: kernel BUG in submit_bh_wbc
run #3: crashed: kernel BUG in submit_bh_wbc
run #4: crashed: kernel BUG in submit_bh_wbc
run #5: crashed: kernel BUG in submit_bh_wbc
run #6: crashed: general protection fault in bdevname
run #7: crashed: kernel BUG in submit_bh_wbc
run #8: crashed: kernel BUG in submit_bh_wbc
run #9: crashed: kernel BUG in submit_bh_wbc
run #10: crashed: general protection fault in bdevname
run #11: crashed: kernel BUG in submit_bh_wbc
run #12: crashed: kernel BUG in submit_bh_wbc
run #13: crashed: kernel BUG in submit_bh_wbc
run #14: crashed: general protection fault in bdevname
run #15: crashed: general protection fault in bdevname
run #16: crashed: kernel BUG in submit_bh_wbc
run #17: crashed: general protection fault in bdevname
run #18: crashed: kernel BUG in submit_bh_wbc
run #19: crashed: general protection fault in bdevname
testing current HEAD 78fec1611cbf7b0bdaddfdbf174a3a2463663bff
testing commit 78fec1611cbf7b0bdaddfdbf174a3a2463663bff with gcc (GCC) 8.4.1 20210217
kernel signature: 5292509479cb28a8b6ef097bde1b78ab517ca1116b2d3517019188162f3d9771
run #0: crashed: kernel BUG in submit_bh_wbc
run #1: crashed: kernel BUG in submit_bh_wbc
run #2: crashed: kernel BUG in submit_bh_wbc
run #3: crashed: kernel BUG in submit_bh_wbc
run #4: crashed: kernel BUG in submit_bh_wbc
run #5: crashed: kernel BUG in submit_bh_wbc
run #6: crashed: general protection fault in bdevname
run #7: crashed: kernel BUG in submit_bh_wbc
run #8: crashed: kernel BUG in submit_bh_wbc
run #9: crashed: general protection fault in bdevname
revisions tested: 2, total time: 22m45.06493948s (build: 14m57.850273232s, test: 7m25.490538496s)
the crash still happens on HEAD
commit msg: Linux 4.19.183
crash: general protection fault in bdevname
EXT4-fs (loop5): mount failed
kasan: CONFIG_KASAN_INLINE enabled
EXT4-fs error (device loop4): ext4_fill_super:4446: inode #2: comm syz-executor.4: iget: root inode unallocated
kasan: GPF could be caused by NULL-ptr deref or user memory access
EXT4-fs (loop4): get root inode failed
general protection fault: 0000 [#1] PREEMPT SMP KASAN
EXT4-fs (loop4): mount failed
CPU: 1 PID: 9453 Comm: kmmpd-loop4 Not tainted 4.19.183-syzkaller #0
EXT4-fs error (device loop1): ext4_fill_super:4446: inode #2: comm syz-executor.1: iget: root inode unallocated
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
EXT4-fs (loop1): get root inode failed
RIP: 0010:bdevname+0x29/0xe0 block/partition-generic.c:49
Code: ff 48 b8 00 00 00 00 00 fc ff df 55 48 89 f2 48 89 e5 41 54 53 48 89 fb 48 81 c7 d0 00 00 00 48 89 f9 48 83 ec 10 48 c1 e9 03 <80> 3c 01 00 75 7f 4c 8b a3 d0 00 00 00 48 b8 00 00 00 00 00 fc ff
RSP: 0018:ffff8881c9eefdd0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 000000000000001a
RDX: ffff8881c8a3d050 RSI: ffff8881c8a3d050 RDI: 00000000000000d0
RBP: ffff8881c9eefdf0 R08: ffffed103c5ded8a R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff8881c8a3d000 R14: ffff8881e0738140 R15: ffff8881d0fd7708
FS:  0000000000000000(0000) GS:ffff8881f6500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2388f7e000 CR3: 000000000986d001 CR4: 00000000001606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 kmmpd+0x284/0x9e0 fs/ext4/mmp.c:158
 kthread+0x347/0x410 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Modules linked in:
---[ end trace eda014194a0deb75 ]---
EXT4-fs (loop1): mount failed
RIP: 0010:bdevname+0x29/0xe0 block/partition-generic.c:49
EXT4-fs warning (device loop5): ext4_multi_mount_protect:387: Unable to create kmmpd thread for loop5.
Code: ff 48 b8 00 00 00 00 00 fc ff df 55 48 89 f2 48 89 e5 41 54 53 48 89 fb 48 81 c7 d0 00 00 00 48 89 f9 48 83 ec 10 48 c1 e9 03 <80> 3c 01 00 75 7f 4c 8b a3 d0 00 00 00 48 b8 00 00 00 00 00 fc ff
RSP: 0018:ffff8881c9eefdd0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 000000000000001a
RDX: ffff8881c8a3d050 RSI: ffff8881c8a3d050 RDI: 00000000000000d0
RBP: ffff8881c9eefdf0 R08: ffffed103c5ded8a R09: 0000000000000000
EXT4-fs error (device loop2): ext4_fill_super:4446: inode #2: comm syz-executor.2: iget: root inode unallocated
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff8881c8a3d000 R14: ffff8881e0738140 R15: ffff8881d0fd7708
FS:  0000000000000000(0000) GS:ffff8881f6500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000538978 CR3: 000000000986d004 CR4: 00000000001606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400