bisecting fixing commit since ae83d0b416db002fe95601e7f97f64b59514d936 building syzkaller on 347a5dc3c7886bfe3ce784eabc5ee30100f13e0a testing commit ae83d0b416db002fe95601e7f97f64b59514d936 with gcc (GCC) 8.4.1 20210217 kernel signature: c422004db97986cd892a5574b1ab2296f3b21f278e120b8217303abcae7b9e7a run #0: crashed: WARNING in kcm_write_msgs run #1: crashed: WARNING in kcm_write_msgs 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: boot failed: can't ssh into the instance testing current HEAD f09eacca59d27efc15001795c33dbc78ca070732 testing commit f09eacca59d27efc15001795c33dbc78ca070732 with gcc (GCC) 10.2.1 20210217 kernel signature: baa39d643e86cbfc2df806c49b09166b35266a0effc6c452136e6ba0d50d243d all runs: crashed: WARNING in kcm_write_msgs revisions tested: 2, total time: 29m5.024230426s (build: 14m22.112719077s, test: 13m47.056549015s) the crash still happens on HEAD commit msg: Merge branch 'for-5.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup crash: WARNING in kcm_write_msgs ------------[ cut here ]------------ WARNING: CPU: 1 PID: 7502 at net/kcm/kcmsock.c:628 kcm_write_msgs+0xeb2/0x1730 net/kcm/kcmsock.c:661 Modules linked in: CPU: 1 PID: 7502 Comm: syz-executor.1 Not tainted 5.13.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:kcm_write_msgs+0xeb2/0x1730 net/kcm/kcmsock.c:628 Code: 04 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 6a 07 00 00 48 8b 44 24 58 45 31 c0 4c 89 70 10 e9 4c f5 ff ff <0f> 0b 41 b8 ea ff ff ff e9 3f f5 ff ff 0f 0b e9 e9 f6 ff ff 8b 44 RSP: 0018:ffffc900008e79c0 EFLAGS: 00010246 RAX: ffff888104beb800 RBX: ffff888104beb8c0 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffed1021d871f7 RDI: ffff888104beb8c2 RBP: 00000000000000c0 R08: 0000000000008000 R09: 0000000000000000 R10: fffffbfff17fdb90 R11: 0000000000000000 R12: ffff88810ec38e00 R13: ffff88810a1bef00 R14: ffff8881047096c0 R15: 0000000000008000 FS: 00007f033a8be700(0000) GS:ffff8881f6500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020002940 CR3: 000000011ab36001 CR4: 00000000001706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kcm_sendmsg+0x135e/0x24e0 net/kcm/kcmsock.c:1034 sock_sendmsg_nosec net/socket.c:654 [inline] sock_sendmsg+0xab/0xe0 net/socket.c:674 sock_write_iter+0x211/0x370 net/socket.c:1001 call_write_iter include/linux/fs.h:2114 [inline] new_sync_write+0x4ad/0x5f0 fs/read_write.c:518 vfs_write+0x5c3/0x870 fs/read_write.c:605 ksys_write+0x171/0x1d0 fs/read_write.c:658 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x464149 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:00007f033a8be198 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000464149 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 0000000000522da0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00 R13: 00007f033a8be6bc R14: 00000000ffffffff R15: 0000000000000003 irq event stamp: 7537 hardirqs last enabled at (7545): [] console_unlock+0x72b/0x9c0 kernel/printk/printk.c:2668 hardirqs last disabled at (7580): [] __schedule+0x13e1/0x23d0 kernel/sched/core.c:5043 softirqs last enabled at (7626): [] invoke_softirq kernel/softirq.c:433 [inline] softirqs last enabled at (7626): [] __irq_exit_rcu kernel/softirq.c:637 [inline] softirqs last enabled at (7626): [] irq_exit_rcu+0x250/0x2a0 kernel/softirq.c:649 softirqs last disabled at (7639): [] invoke_softirq kernel/softirq.c:433 [inline] softirqs last disabled at (7639): [] __irq_exit_rcu kernel/softirq.c:637 [inline] softirqs last disabled at (7639): [] irq_exit_rcu+0x250/0x2a0 kernel/softirq.c:649 ---[ end trace f5dcc64d1c9d77bd ]--- KCM: Hard failure on kcm_write_msgs