bisecting fixing commit since 54b4fa6d39551639cb10664f6ac78b01993a1d7e building syzkaller on c8d1cc20df5ca5d9ea437054720fa3cfdfa1f578 testing commit 54b4fa6d39551639cb10664f6ac78b01993a1d7e with gcc (GCC) 8.4.1 20210217 kernel signature: 9b00cfc994d63555a298f6052b8030de4bf1a5210510628f565a10efb7087e6d run #0: crashed: WARNING in kcm_write_msgs run #1: crashed: WARNING in corrupted run #2: crashed: WARNING in kcm_write_msgs run #3: crashed: WARNING in kcm_write_msgs run #4: crashed: WARNING in kcm_write_msgs run #5: crashed: WARNING in kcm_write_msgs run #6: crashed: WARNING in kcm_write_msgs run #7: crashed: WARNING in kcm_write_msgs run #8: crashed: WARNING in kcm_write_msgs run #9: crashed: WARNING in kcm_write_msgs run #10: crashed: WARNING in kcm_write_msgs run #11: crashed: WARNING in kcm_write_msgs run #12: crashed: WARNING in kcm_write_msgs run #13: crashed: WARNING in kcm_write_msgs run #14: crashed: WARNING in kcm_write_msgs run #15: crashed: WARNING in kcm_write_msgs run #16: crashed: WARNING in kcm_write_msgs run #17: crashed: WARNING in kcm_write_msgs run #18: crashed: WARNING in kcm_write_msgs run #19: crashed: WARNING in kcm_write_msgs testing current HEAD 2d19be4653f5e74ed95560b69f94eb6791d49af3 testing commit 2d19be4653f5e74ed95560b69f94eb6791d49af3 with gcc (GCC) 8.4.1 20210217 kernel signature: 710d167e46c3b63847c4ae6e5e8cc21e8a4cd2be760fb96c573e2b558d7cf2a1 run #0: crashed: possible deadlock in __sock_release run #1: crashed: possible deadlock in __sock_release run #2: crashed: possible deadlock in __sock_release run #3: crashed: possible deadlock in __sock_release run #4: crashed: possible deadlock in __sock_release run #5: crashed: WARNING in kcm_write_msgs run #6: crashed: possible deadlock in __sock_release run #7: crashed: possible deadlock in __sock_release run #8: crashed: WARNING in kcm_write_msgs run #9: crashed: WARNING in kcm_write_msgs revisions tested: 2, total time: 23m34.328673918s (build: 16m3.588839586s, test: 6m32.406322493s) the crash still happens on HEAD commit msg: Linux 4.19.177 crash: WARNING in kcm_write_msgs ------------[ cut here ]------------ WARNING: CPU: 1 PID: 8568 at net/kcm/kcmsock.c:629 kcm_write_msgs.cold.34+0x5f/0x13e net/kcm/kcmsock.c:629 Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 8568 Comm: syz-executor.1 Not tainted 4.19.177-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+0x123/0x171 lib/dump_stack.c:118 panic+0x1cd/0x375 kernel/panic.c:186 __warn.cold.8+0x1b/0x36 kernel/panic.c:541 report_bug+0x1a1/0x200 lib/bug.c:186 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:kcm_write_msgs.cold.34+0x5f/0x13e net/kcm/kcmsock.c:629 Code: c7 c7 c0 6d d0 87 4c 89 5d d0 e8 7a 34 ec ff 0f 0b 4c 8b 5d d0 e9 ae d5 5f ff 48 c7 c7 c0 6d d0 87 4c 89 5d d0 e8 5f 34 ec ff <0f> 0b 8b 85 7c ff ff ff ba ea ff ff ff 4c 8b 5d d0 89 45 c4 e9 08 RSP: 0018:ffff8881dda878f8 EFLAGS: 00010282 RAX: 0000000000000024 RBX: ffff8881e7ce6680 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff876797e0 RDI: ffffffff8a1859a0 RBP: ffff8881dda879b8 R08: ffffed103ed25079 R09: ffffed103ed25078 R10: ffffed103ed25078 R11: ffff8881f69283c7 R12: 00000000000000c0 R13: ffff8881da9e21c0 R14: ffff8881dfd37380 R15: ffff8881e7ce65c0 kcm_sendmsg+0x1897/0x25b0 net/kcm/kcmsock.c:1035 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xb5/0xf0 net/socket.c:632 sock_write_iter+0x215/0x420 net/socket.c:901 call_write_iter include/linux/fs.h:1821 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x443/0x890 fs/read_write.c:487 vfs_write+0x150/0x4d0 fs/read_write.c:549 ksys_write+0x103/0x260 fs/read_write.c:599 __do_sys_write fs/read_write.c:611 [inline] __se_sys_write fs/read_write.c:608 [inline] __x64_sys_write+0x6e/0xb0 fs/read_write.c:608 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4641a9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f5009adf198 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000c4c RCX: 00000000004641a9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000053bf00 R13: 00007f5009adf6bc R14: 00000000ffffffff R15: 0000000000000003 Kernel Offset: disabled Rebooting in 86400 seconds..