Subject: Re: [syzbot] [rdma?] WARNING in ib_uverbs_release_dev

From: Leon Romanovsky <[email-masked]>
Date: Wed, 19 Jun 2024 12:15:57 +0300

On Tue, Jun 18, 2024 at 11:37:18PM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    2ccbdf43d5e7 Merge tag 'for-linus' of git://git.kernel.org..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=179e93fe980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=fa0ce06dcc735711
> dashboard link: https://syzkaller.appspot.com/bug?extid=19ec7595e3aa1a45f623
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/27e64d7472ce/disk-2ccbdf43.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/e1c494bb5c9c/vmlinux-2ccbdf43.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/752498985a5e/bzImage-2ccbdf43.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: [email-masked]
> 
> smc: removing ib device syz0
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 51 at kernel/rcu/srcutree.c:653 cleanup_srcu_struct+0x404/0x4d0 kernel/rcu/srcutree.c:653
> Modules linked in:
> CPU: 0 PID: 51 Comm: kworker/u8:3 Not tainted 6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
> Workqueue: ib-unreg-wq ib_unregister_work
> RIP: 0010:cleanup_srcu_struct+0x404/0x4d0 kernel/rcu/srcutree.c:653
> Code: 12 80 00 48 c7 03 00 00 00 00 48 83 c4 48 5b 41 5c 41 5d 41 5e 41 5f 5d e9 14 67 34 0a 90 0f 0b 90 eb e7 90 0f 0b 90 eb e1 90 <0f> 0b 90 eb db 90 0f 0b 90 eb 0a 90 0f 0b 90 eb 04 90 0f 0b 90 48
> RSP: 0018:ffffc90000bb7970 EFLAGS: 00010202
> RAX: 0000000000000001 RBX: ffff88802a1bc980 RCX: 0000000000000002
> RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffe8ffffd74c58
> RBP: 0000000000000001 R08: ffffe8ffffd74c5f R09: 1ffffd1ffffae98b
> R10: dffffc0000000000 R11: fffff91ffffae98c R12: dffffc0000000000
> R13: ffff88802285b5f0 R14: ffff88802285b000 R15: ffff88802a1bc800
> FS:  0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fa3852cae10 CR3: 000000000e132000 CR4: 0000000000350ef0
> Call Trace:
>  <TASK>
>  ib_uverbs_release_dev+0x4e/0x80 drivers/infiniband/core/uverbs_main.c:136
>  device_release+0x9b/0x1c0
>  kobject_cleanup lib/kobject.c:689 [inline]
>  kobject_release lib/kobject.c:720 [inline]
>  kref_put include/linux/kref.h:65 [inline]
>  kobject_put+0x231/0x480 lib/kobject.c:737
>  remove_client_context+0xb9/0x1e0 drivers/infiniband/core/device.c:776
>  disable_device+0x13b/0x360 drivers/infiniband/core/device.c:1282
>  __ib_unregister_device+0x6d/0x170 drivers/infiniband/core/device.c:1475
>  ib_unregister_work+0x19/0x30 drivers/infiniband/core/device.c:1586
>  process_one_work kernel/workqueue.c:3231 [inline]
>  process_scheduled_works+0xa2e/0x1830 kernel/workqueue.c:3312
>  worker_thread+0x86d/0xd70 kernel/workqueue.c:3393
>  kthread+0x2f2/0x390 kernel/kthread.c:389
>  ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
>  </TASK>

I see that this is caused by call to ib_unregister_device_queued() as a
response to NETDEV_UNREGISTER event, but we don't flush anything before.
How can we be sure that ib_device is not used anymore?

Thanks