syzbot


WARNING in filename_mknodat

Status: moderation: reported on 2026/02/17 13:36
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+9760e4d233c54d8a2151@syzkaller.appspotmail.com
First crash: 10d, last: 20h40m

Sample crash report:
loop0: detected capacity change from 0 to 32768
gfs2: fsid=syz:syz: Trying to join cluster "lock_nolock", "syz:syz"
gfs2: fsid=syz:syz: Now mounting FS (format 1801)...
gfs2: fsid=syz:syz.0: journal 0 mapped with 1 extents in 0ms
gfs2: fsid=syz:syz.0: first mount done, others may mount
------------[ cut here ]------------
DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)): count = 0x0, magic = 0xffff88804777c9b8, owner = 0x0, curr 0xffff88803045c900, list empty
WARNING: kernel/locking/rwsem.c:1381 at __up_write kernel/locking/rwsem.c:1380 [inline], CPU#0: syz.0.0/5326
WARNING: kernel/locking/rwsem.c:1381 at up_write+0x2d6/0x410 kernel/locking/rwsem.c:1643, CPU#0: syz.0.0/5326
Modules linked in:
CPU: 0 UID: 0 PID: 5326 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__up_write kernel/locking/rwsem.c:1380 [inline]
RIP: 0010:up_write+0x388/0x410 kernel/locking/rwsem.c:1643
Code: cc 8b 49 c7 c2 80 eb cc 8b 4c 0f 44 d0 48 8b 7c 24 08 48 c7 c6 e0 ed cc 8b 48 8b 14 24 4c 89 f1 4d 89 e0 4c 8b 4c 24 10 41 52 <67> 48 0f b9 3a 48 83 c4 08 e8 2a 3d 0b 03 e9 67 fd ff ff 48 c7 c1
RSP: 0018:ffffc9000edf7d80 EFLAGS: 00010246
RAX: ffffffff8bcceb60 RBX: ffff88804777c9b8 RCX: ffff88804777c9b8
RDX: 0000000000000000 RSI: ffffffff8bccede0 RDI: ffffffff9014f010
RBP: ffff88804777ca10 R08: 0000000000000000 R09: ffff88803045c900
R10: ffffffff8bcceb60 R11: ffffed1008eef939 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff88804777c9b8 R15: 1ffff11008eef938
FS:  00007fbc55b296c0(0000) GS:ffff88808ca5b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001600 CR3: 000000000bbd7000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 inode_unlock include/linux/fs.h:1038 [inline]
 end_dirop fs/namei.c:2947 [inline]
 end_creating include/linux/namei.h:126 [inline]
 end_creating_path fs/namei.c:4962 [inline]
 filename_mknodat+0x458/0x660 fs/namei.c:5156
 __do_sys_mknodat fs/namei.c:5173 [inline]
 __se_sys_mknodat+0x3b/0x150 fs/namei.c:5169
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbc54b9c629
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fbc55b29028 EFLAGS: 00000246 ORIG_RAX: 0000000000000103
RAX: ffffffffffffffda RBX: 00007fbc54e15fa0 RCX: 00007fbc54b9c629
RDX: 0000000000006000 RSI: 0000200000001600 RDI: 0000000000000006
RBP: 00007fbc54c32b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000700 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbc54e16038 R14: 00007fbc54e15fa0 R15: 00007ffd7dd556d8
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	49 c7 c2 80 eb cc 8b 	mov    $0xffffffff8bcceb80,%r10
   7:	4c 0f 44 d0          	cmove  %rax,%r10
   b:	48 8b 7c 24 08       	mov    0x8(%rsp),%rdi
  10:	48 c7 c6 e0 ed cc 8b 	mov    $0xffffffff8bccede0,%rsi
  17:	48 8b 14 24          	mov    (%rsp),%rdx
  1b:	4c 89 f1             	mov    %r14,%rcx
  1e:	4d 89 e0             	mov    %r12,%r8
  21:	4c 8b 4c 24 10       	mov    0x10(%rsp),%r9
  26:	41 52                	push   %r10
* 28:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2d:	48 83 c4 08          	add    $0x8,%rsp
  31:	e8 2a 3d 0b 03       	call   0x30b3d60
  36:	e9 67 fd ff ff       	jmp    0xfffffda2
  3b:	48                   	rex.W
  3c:	c7                   	.byte 0xc7
  3d:	c1                   	.byte 0xc1

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/23 12:47 upstream 6de23f81a5e0 7c9658af .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in filename_mknodat
2026/02/14 13:08 upstream 770aaedb461a 1e62d198 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in filename_mknodat
2026/02/13 13:32 upstream 7449f86bafcd 6a673c50 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in filename_mknodat
2026/02/20 04:12 linux-next 44982d352c33 17d780d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in filename_mknodat
2026/02/19 15:30 linux-next 44982d352c33 73a252ac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in filename_mknodat
2026/02/16 16:12 linux-next 635c467cc14e 5d52cba5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in filename_mknodat
* Struck through repros no longer work on HEAD.