Subject: [syzbot] [fuse?] linux-next test error: WARNING in fuse_dev_install_with_pq

From: syzbot <[email-masked]>
Date: Wed, 15 Apr 2026 08:49:33 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    936c21068d7a Add linux-next specific files for 20260415
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14940702580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=20564048a4030a77
dashboard link: https://syzkaller.appspot.com/bug?extid=a761f017e231803b82cd
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/65e69b0763ee/disk-936c2106.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/eec951f96cd3/vmlinux-936c2106.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d1e1822e93a4/bzImage-936c2106.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

------------[ cut here ]------------
fud->pq.processing
WARNING: fs/fuse/dev.c:482 at fuse_dev_install_with_pq+0x23b/0x270 fs/fuse/dev.c:482, CPU#1: syz.4.290/6132
Modules linked in:
CPU: 1 UID: 0 PID: 6132 Comm: syz.4.290 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:fuse_dev_install_with_pq+0x23b/0x270 fs/fuse/dev.c:482
Code: 85 6d fe ff ff e8 55 84 84 fe 4d 85 ed 0f 94 c0 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 36 84 84 fe 90 <0f> 0b 90 41 80 3c 2e 00 0f 85 8a fe ff ff e9 8d fe ff ff 44 89 f1
RSP: 0018:ffffc90005357660 EFLAGS: 00010293
RAX: ffffffff83401a0a RBX: ffff88802cb4b000 RCX: ffff88802d041ec0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: ffff88802804d50f R09: 1ffff11005009aa1
R10: dffffc0000000000 R11: ffffed1005009aa2 R12: ffff88802d2a2000
R13: ffff88802804d598 R14: 1ffff11005009ab3 R15: ffff88802804d500
FS:  0000555556ded500(0000) GS:ffff888125fbc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f58e1e0ba40 CR3: 000000003e02c000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 fuse_dev_install fs/fuse/dev.c:496 [inline]
 fuse_dev_alloc_install+0x61/0x80 fs/fuse/dev.c:508
 cuse_channel_open+0x124/0x7b0 fs/fuse/cuse.c:524
 misc_open+0x2de/0x350 drivers/char/misc.c:163
 chrdev_open+0x4d0/0x5f0 fs/char_dev.c:411
 do_dentry_open+0x83d/0x13e0 fs/open.c:947
 vfs_open+0x3b/0x350 fs/open.c:1079
 do_open fs/namei.c:4699 [inline]
 path_openat+0x2e43/0x38a0 fs/namei.c:4858
 do_file_open+0x23e/0x4a0 fs/namei.c:4887
 do_sys_openat2+0x113/0x200 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1381
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f58e1e7c819
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:00007ffdb95bfa38 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f58e20f5fa0 RCX: 00007f58e1e7c819
RDX: 0000000000000002 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007f58e1f12c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f58e20f5fac R14: 00007f58e20f5fa0 R15: 00007f58e20f5fa0
 </TASK>

---
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