Re: [syzbot] [iommu?] WARNING in iommufd_device_unbind

[syzbot <syzbot+c92878e123785b1fa2db@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in iommufd_device_unbind

iommufd: Time out waiting for iommufd object to become free
------------[ cut here ]------------
WARNING: CPU: 1 PID: 7718 at drivers/iommu/iommufd/iommufd_private.h:190 iommufd_object_destroy_user drivers/iommu/iommufd/iommufd_private.h:190 [inline]
WARNING: CPU: 1 PID: 7718 at drivers/iommu/iommufd/iommufd_private.h:190 iommufd_device_unbind+0x81/0xa0 drivers/iommu/iommufd/device.c:280
Modules linked in:
CPU: 1 UID: 0 PID: 7718 Comm: syz.2.28 Not tainted 6.12.0-syzkaller-08446-g228a1157fb9f-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:iommufd_object_destroy_user drivers/iommu/iommufd/iommufd_private.h:190 [inline]
RIP: 0010:iommufd_device_unbind+0x81/0xa0 drivers/iommu/iommufd/device.c:280
Code: 00 e8 13 a6 01 00 89 c3 31 ff 89 c6 e8 78 61 4c fc 85 db 75 0f e8 2f 5d 4c fc 5b 41 5e 41 5f c3 cc cc cc cc e8 20 5d 4c fc 90 <0f> 0b 90 eb eb 89 f9 80 e1 07 80 c1 03 38 c1 7c b8 e8 a9 f1 b3 fc
RSP: 0000:ffffc9000558fc38 EFLAGS: 00010293
RAX: ffffffff8548efc0 RBX: 00000000fffffff0 RCX: ffff88802b943c00
RDX: 0000000000000000 RSI: 00000000fffffff0 RDI: 0000000000000000
RBP: ffffc9000558fd70 R08: ffffffff8548efa8 R09: 1ffff11004af9f00
R10: dffffc0000000000 R11: ffffed1004af9f01 R12: ffff88803200d698
R13: ffff88803200d680 R14: ffff88807d293c00 R15: dffffc0000000000
FS:  00007f8c8c5a06c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020b04000 CR3: 000000006c9d0000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 iommufd_selftest_destroy+0x95/0xe0 drivers/iommu/iommufd/selftest.c:1621
 iommufd_object_remove+0x3b6/0x530 drivers/iommu/iommufd/main.c:185
 iommufd_fops_ioctl+0x4d6/0x5a0 drivers/iommu/iommufd/main.c:409
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8c8b77e759
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8c8c5a0038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f8c8b936058 RCX: 00007f8c8b77e759
RDX: 0000000020000400 RSI: 0000000000003b80 RDI: 0000000000000003
RBP: 00007f8c8b7f175e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f8c8b936058 R15: 00007fffb80aeab8
 </TASK>


Tested on:

commit:         228a1157 Merge tag '6.13-rc-part1-SMB3-client-fixes' o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=178f975f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=402159daa216c89d
dashboard link: https://syzkaller.appspot.com/bug?extid=c92878e123785b1fa2db
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1585a9c0580000