Re: [syzbot] [virt?] [dri?] WARNING in virtio_gpu_alloc_vbufs

syzbot has found a reproducer for the following issue on:

HEAD commit:    2d2338c93da7 Merge tag 'i2c-fixes-7.2-rc6' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15f3edb9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=145fa60d73086782
dashboard link: https://syzkaller.appspot.com/bug?extid=1b129b44597a126d2d79
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=173115b9580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1782f4c6580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-2d2338c9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/89fdd9cdbdc2/vmlinux-2d2338c9.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a7930b1db6cb/bzImage-2d2338c9.xz

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

[drm] features: -virgl +edid -resource_blob -host_visible
[drm] features: -context_init -blob_alignment
------------[ cut here ]------------
kmem_cache of name 'virtio-gpu-vbufs' already exists
WARNING: mm/slab_common.c:111 at kmem_cache_sanity_check mm/slab_common.c:111 [inline], CPU#0: syz.0.17/5926
WARNING: mm/slab_common.c:111 at __kmem_cache_create_args+0xa6/0x420 mm/slab_common.c:352, CPU#0: syz.0.17/5926
Modules linked in:
CPU: 0 UID: 0 PID: 5926 Comm: syz.0.17 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:kmem_cache_sanity_check mm/slab_common.c:111 [inline]
RIP: 0010:__kmem_cache_create_args+0xa9/0x420 mm/slab_common.c:352
Code: 48 8b 43 60 48 8d 58 a0 48 3d b0 82 d8 8e 74 1f 48 8b 7b 58 48 89 ee e8 c5 50 5e 09 85 c0 75 e0 48 8d 3d 1a 39 ce 0e 48 89 ee <67> 48 0f b9 3a be 20 00 00 00 48 89 ef e8 45 52 5e 09 48 85 c0 0f
RSP: 0018:ffffc9000388ef58 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8881012c77c0 RCX: fffff52000711dc6
RDX: 0000000000000000 RSI: ffffffff8c6f8d40 RDI: ffffffff91275ec0
RBP: ffffffff8c6f8d40 R08: 0000000000000000 R09: fffffbfff22450fa
R10: ffffc9000388ef58 R11: 0000000000000000 R12: 0000000000000000
R13: ffffc9000388efc8 R14: 00000000000000d8 R15: 0000000000000000
FS:  000055557ecab500(0000) GS:ffff8880d5dd8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33324008 CR3: 000000002ad27000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __kmem_cache_create include/linux/slab.h:399 [inline]
 virtio_gpu_alloc_vbufs+0xc2/0x150 drivers/gpu/drm/virtio/virtgpu_vq.c:75
 virtio_gpu_init.cold+0x51c/0x126e drivers/gpu/drm/virtio/virtgpu_kms.c:228
 virtio_gpu_probe+0x21c/0x360 drivers/gpu/drm/virtio/virtgpu_drv.c:103
 virtio_dev_probe+0x6a2/0xbe0 drivers/virtio/virtio.c:347
 call_driver_probe drivers/base/dd.c:628 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:706
 __driver_probe_device+0x20e/0x450 drivers/base/dd.c:868
 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
 __device_attach_driver+0x1df/0x320 drivers/base/dd.c:1026
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:500
 __device_attach+0x1e4/0x4d0 drivers/base/dd.c:1098
 device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1153
 bus_probe_device+0x64/0x160 drivers/base/bus.c:620
 device_add+0x121d/0x1970 drivers/base/core.c:3772
 register_virtio_device+0x4f0/0x5d0 drivers/virtio/virtio.c:568
 virtio_pci_probe+0x255/0x410 drivers/virtio/virtio_pci_common.c:722
 local_pci_probe+0xdd/0x1b0 drivers/pci/pci-driver.c:332
 pci_call_probe+0x176/0x800 drivers/pci/pci-driver.c:394
 __pci_device_probe drivers/pci/pci-driver.c:455 [inline]
 pci_device_probe+0x1cd/0x370 drivers/pci/pci-driver.c:489
 call_driver_probe drivers/base/dd.c:628 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:706
 __driver_probe_device+0x20e/0x450 drivers/base/dd.c:868
 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
 __device_attach_driver+0x1df/0x320 drivers/base/dd.c:1026
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:500
 __device_attach+0x1e4/0x4d0 drivers/base/dd.c:1098
 device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1153
 pci_bus_add_device+0xc5/0x100 drivers/pci/bus.c:373
 pci_bus_add_devices+0x9a/0x1f0 drivers/pci/bus.c:394
 pci_rescan_bus+0x2a/0x40 drivers/pci/probe.c:3500
 rescan_store+0xfb/0x130 drivers/pci/pci-sysfs.c:473
 bus_attr_store+0x74/0xb0 drivers/base/bus.c:172
 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1050 fs/read_write.c:687
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fba4739e019
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:00007ffeb190b8e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fba47625fa0 RCX: 00007fba4739e019
RDX: 0000000000000001 RSI: 0000200000000a00 RDI: 0000000000000005
RBP: 00007fba4743500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fba47625fac R14: 00007fba47625fa0 R15: 00007fba47625fa0
 </TASK>
----------------
Code disassembly (best guess):
   0:	48 8b 43 60          	mov    0x60(%rbx),%rax
   4:	48 8d 58 a0          	lea    -0x60(%rax),%rbx
   8:	48 3d b0 82 d8 8e    	cmp    $0xffffffff8ed882b0,%rax
   e:	74 1f                	je     0x2f
  10:	48 8b 7b 58          	mov    0x58(%rbx),%rdi
  14:	48 89 ee             	mov    %rbp,%rsi
  17:	e8 c5 50 5e 09       	call   0x95e50e1
  1c:	85 c0                	test   %eax,%eax
  1e:	75 e0                	jne    0x0
  20:	48 8d 3d 1a 39 ce 0e 	lea    0xece391a(%rip),%rdi        # 0xece3941
  27:	48 89 ee             	mov    %rbp,%rsi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	be 20 00 00 00       	mov    $0x20,%esi
  34:	48 89 ef             	mov    %rbp,%rdi
  37:	e8 45 52 5e 09       	call   0x95e5281
  3c:	48 85 c0             	test   %rax,%rax
  3f:	0f                   	.byte 0xf


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