[syzbot ci] Re: multiple-filesystems: prepare for changes to VFS locking
From: syzbot ci
Date: Wed Sep 30 2026 - 06:31:42 EST
syzbot ci has tested the following series
[v1] multiple-filesystems: prepare for changes to VFS locking
https://lore.kernel.org/all/20260929034158.1455429-1-neilb@xxxxxxxxxxx
* [PATCH 1/7] VFS/xfs/ntfs: drop parent lock across d_alloc_parallel() in d_add_ci()
* [PATCH 2/7] shmem: use d_duplicate()
* [PATCH 3/7] coda: don't d_drop() early.
* [PATCH 4/7] configfs: remove d_add() calls before configfs_attach_group()
* [PATCH 5/7] hostfs: don't d_drop() before d_splice_alias() in hostfs_mkdir()
* [PATCH 6/7] procfs: drop parent lock for d_alloc_parallel() in iterate_shared()
* [PATCH 7/7] ovl: stop using lookup_one() in ovl_iterate().
and found the following issue:
WARNING in __d_instantiate
Full report is available here:
https://ci.syzbot.org/series/b87296ff-c49f-416e-834c-a886ea8bd6c3
***
WARNING in __d_instantiate
tree: linux-next
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next
base: 3879f51857325da9bf3cfb073280257cd16ae067
arch: amd64
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
config: https://ci.syzbot.org/builds/dd8fcfa5-13f0-458f-bd3b-9c06d4d67a78/config
syz repro: https://ci.syzbot.org/findings/fdffe42d-ac1a-40d9-b05c-014808f5b0ec/syz_repro
------------[ cut here ]------------
d_in_lookup(dentry)
WARNING: fs/dcache.c:2197 at __d_instantiate+0x3f4/0x700 fs/dcache.c:2197, CPU#1: syz.0.17/5823
Modules linked in:
CPU: 1 UID: 0 PID: 5823 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:__d_instantiate+0x3f4/0x700 fs/dcache.c:2197
Code: 03 41 80 f6 01 41 0f b6 ce c1 e1 0d 09 c1 89 0b 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 03 26 96 09 cc e8 0d 84 75 ff 90 <0f> 0b 90 e9 7f fd ff ff e8 ff 83 75 ff 41 81 cc 00 00 01 00 e9 34
RSP: 0018:ffffc900038d73a0 EFLAGS: 00010293
RAX: ffffffff825242a3 RBX: ffff8881b4eef380 RCX: ffff888169801e00
RDX: 0000000000000000 RSI: 0000000001000000 RDI: 0000000000000000
RBP: 0000000001000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200071ae6c R12: 0000000000280000
R13: dffffc0000000000 R14: ffff8881bc29f3e0 R15: ffff8881bc29f3e4
FS: 00007f15d1af96c0(0000) GS:ffff8882a8cc9000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 00000001bd5c4000 CR4: 00000000000006f0
Call Trace:
<TASK>
d_make_persistent+0x8e/0x180 fs/dcache.c:3139
shmem_mknod+0x2d4/0x340 mm/shmem.c:3851
shmem_whiteout mm/shmem.c:3982 [inline]
shmem_rename2+0x267/0x430 mm/shmem.c:4022
vfs_rename+0xbd9/0xef0 fs/namei.c:6219
ovl_do_rename_rd fs/overlayfs/overlayfs.h:371 [inline]
ovl_check_rename_whiteout fs/overlayfs/super.c:593 [inline]
ovl_make_workdir fs/overlayfs/super.c:713 [inline]
ovl_get_workdir+0x93d/0x1980 fs/overlayfs/super.c:836
ovl_fill_super_creds fs/overlayfs/super.c:1449 [inline]
ovl_fill_super+0x1702/0x4360 fs/overlayfs/super.c:1561
vfs_get_super fs/super.c:1405 [inline]
get_tree_nodev+0xbb/0x150 fs/super.c:1424
vfs_get_tree+0x92/0x2a0 fs/super.c:1947
fc_mount fs/namespace.c:1198 [inline]
do_new_mount_fc fs/namespace.c:3772 [inline]
do_new_mount+0x319/0xdc0 fs/namespace.c:3848
do_mount fs/namespace.c:4181 [inline]
__do_sys_mount fs/namespace.c:4397 [inline]
__se_sys_mount+0x31d/0x420 fs/namespace.c:4374
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f15d0b9e159
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:00007f15d1af9028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f15d0e25fa0 RCX: 00007f15d0b9e159
RDX: 0000200000000440 RSI: 0000200000000100 RDI: 0000000000000000
RBP: 00007f15d0c3506b R08: 0000200000000080 R09: 0000000000000000
R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f15d0e26038 R14: 00007f15d0e25fa0 R15: 00007ffe9e1b3308
</TASK>
***
If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
Tested-by: syzbot@xxxxxxxxxxxxxxxxxxxxxxxxx
---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
To test a fix for this bug, please reply with `#syz test`
(on a separate line) and attach the patch to the email.
Notes:
- The patch will be applied on top of the tested series (as an
incremental fix).
- To test a new version of the whole series, please send it directly
to syzbot@xxxxxxxxxxxxxxx.
- Arguments like custom git repos and branches are not supported.