bisecting fixing commit since 88b06399c9c766c283e070b022b5ceafa4f63f19 building syzkaller on b3c3bb8e115e28ac78d37da1ee8931351d6cb113 testing commit 88b06399c9c766c283e070b022b5ceafa4f63f19 with gcc (GCC) 10.2.1 20210217 kernel signature: 6512804c55f2e3e68ebf099b572c030ca24a7c2b037191e210a922412fb14f76 run #0: crashed: WARNING in inc_nlink run #1: crashed: WARNING in inc_nlink run #2: crashed: WARNING in inc_nlink run #3: crashed: WARNING in inc_nlink run #4: crashed: WARNING in inc_nlink run #5: crashed: WARNING in inc_nlink run #6: crashed: WARNING in inc_nlink run #7: crashed: WARNING in inc_nlink run #8: crashed: WARNING in inc_nlink run #9: crashed: WARNING in inc_nlink run #10: crashed: WARNING in inc_nlink run #11: crashed: WARNING in inc_nlink run #12: crashed: WARNING in inc_nlink run #13: crashed: WARNING in inc_nlink run #14: crashed: WARNING in inc_nlink run #15: crashed: WARNING in inc_nlink run #16: crashed: WARNING in inc_nlink run #17: crashed: WARNING in inc_nlink run #18: crashed: WARNING in inc_nlink run #19: crashed: WARNING in corrupted testing current HEAD 8096acd7442e613fad0354fc8dfdb2003cceea0b testing commit 8096acd7442e613fad0354fc8dfdb2003cceea0b with gcc (GCC) 10.2.1 20210217 kernel signature: 8ffe630e41f85900b1d8dfa7ead9df134594f8b38def5221c3c6a06b2d45d3b8 all runs: crashed: WARNING in inc_nlink revisions tested: 2, total time: 21m34.428196426s (build: 13m39.961068716s, test: 7m19.493547145s) the crash still happens on HEAD commit msg: Merge tag 'net-5.14-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net crash: WARNING in inc_nlink VFS: Found a V7 FS (block size = 512) on device loop1 ------------[ cut here ]------------ WARNING: CPU: 0 PID: 10163 at fs/inode.c:361 inc_nlink+0x126/0x150 fs/inode.c:365 Modules linked in: CPU: 0 PID: 10163 Comm: syz-executor.1 Not tainted 5.14.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:inc_nlink+0x126/0x150 fs/inode.c:361 Code: ef 89 44 24 04 e8 ca 8a f0 ff 8b 44 24 04 e9 4d ff ff ff 48 89 ef e8 49 8a f0 ff e9 14 ff ff ff 48 89 ef e8 3c 8a f0 ff eb cc <0f> 0b e9 6a ff ff ff e8 3e 8a f0 ff e9 53 ff ff ff e8 34 8a f0 ff RSP: 0018:ffffc9000b557df0 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffff88804a6899d8 RCX: 00000000000000a8 RDX: 1ffff110094d1356 RSI: ffff88804a6899d8 RDI: ffff88804a689ab0 RBP: ffff88804a689a20 R08: ffff88804a6899f8 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffff88804a6899d8 R13: ffff88803ba37040 R14: 0000000000000000 R15: ffff88804a6899d8 FS: 00007fdd7eed2700(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffeffeb5960 CR3: 0000000013fc2000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: inode_inc_link_count include/linux/fs.h:2433 [inline] sysv_mkdir+0x17/0xf0 fs/sysv/namei.c:119 vfs_mkdir+0x43d/0x6a0 fs/namei.c:3823 do_mkdirat+0x20c/0x280 fs/namei.c:3848 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665f9 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:00007fdd7eed2188 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 00000000004665f9 RDX: 00000000000000b8 RSI: 0000000020000040 RDI: 0000000000000005 RBP: 00000000004bfce1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60 R13: 00007ffc45ecd3cf R14: 00007fdd7eed2300 R15: 0000000000022000