linux-kernel - Re: [PATCH] vdpa/mlx5: Fix error path during device add

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Message-ID: <CACGkMEswM_3uhOHnzGwOMjfiPqpMgTnjVRhgpWquzTwVpwNr6g@mail.gmail.com>
Date: Wed, 6 Nov 2024 11:30:14 +0800
From: Jason Wang <jasowang@...hat.com>
To: Dragos Tatulea <dtatulea@...dia.com>
Cc: "Michael S . Tsirkin" <mst@...hat.com>, Eugenio Perez Martin <eperezma@...hat.com>, 
	Si-Wei Liu <si-wei.liu@...cle.com>, virtualization@...ts.linux.dev, 
	Gal Pressman <gal@...dia.com>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Parav Pandit <parav@...dia.com>, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Subject: Re: [PATCH] vdpa/mlx5: Fix error path during device add

On Wed, Nov 6, 2024 at 2:52 AM Dragos Tatulea <dtatulea@...dia.com> wrote:
>
> In the error recovery path of mlx5_vdpa_dev_add(), the cleanup is
> executed and at the end put_device() is called which ends up calling
> mlx5_vdpa_free(). This function will execute the same cleanup all over
> again. Most resources support being cleaned up twice, but the recent
> mlx5_vdpa_destroy_mr_resources() doesn't.
>
> This change drops the explicit cleanup from within the
> mlx5_vdpa_dev_add() and lets mlx5_vdpa_free() do its work.
>
> This issue was discovered while trying to add 2 vdpa devices with the
> same name:
> $> vdpa dev add name vdpa-0 mgmtdev auxiliary/mlx5_core.sf.2
> $> vdpa dev add name vdpa-0 mgmtdev auxiliary/mlx5_core.sf.3
>
> ... yields the following dump:
>
>   BUG: kernel NULL pointer dereference, address: 00000000000000b8
>   #PF: supervisor read access in kernel mode
>   #PF: error_code(0x0000) - not-present page
>   PGD 0 P4D 0
>   Oops: Oops: 0000 [#1] SMP
>   CPU: 4 UID: 0 PID: 2811 Comm: vdpa Not tainted 6.12.0-rc6 #1
>   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
>   RIP: 0010:destroy_workqueue+0xe/0x2a0
>   Code: ...
>   RSP: 0018:ffff88814920b9a8 EFLAGS: 00010282
>   RAX: 0000000000000000 RBX: ffff888105c10000 RCX: 0000000000000000
>   RDX: 0000000000000001 RSI: ffff888100400168 RDI: 0000000000000000
>   RBP: 0000000000000000 R08: ffff888100120c00 R09: ffffffff828578c0
>   R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
>   R13: ffff888131fd99a0 R14: 0000000000000000 R15: ffff888105c10580
>   FS:  00007fdfa6b4f740(0000) GS:ffff88852ca00000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 00000000000000b8 CR3: 000000018db09006 CR4: 0000000000372eb0
>   DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>   DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>   Call Trace:
>    <TASK>
>    ? __die+0x20/0x60
>    ? page_fault_oops+0x150/0x3e0
>    ? exc_page_fault+0x74/0x130
>    ? asm_exc_page_fault+0x22/0x30
>    ? destroy_workqueue+0xe/0x2a0
>    mlx5_vdpa_destroy_mr_resources+0x2b/0x40 [mlx5_vdpa]
>    mlx5_vdpa_free+0x45/0x150 [mlx5_vdpa]
>    vdpa_release_dev+0x1e/0x50 [vdpa]
>    device_release+0x31/0x90
>    kobject_put+0x8d/0x230
>    mlx5_vdpa_dev_add+0x328/0x8b0 [mlx5_vdpa]
>    vdpa_nl_cmd_dev_add_set_doit+0x2b8/0x4c0 [vdpa]
>    genl_family_rcv_msg_doit+0xd0/0x120
>    genl_rcv_msg+0x180/0x2b0
>    ? __vdpa_alloc_device+0x1b0/0x1b0 [vdpa]
>    ? genl_family_rcv_msg_dumpit+0xf0/0xf0
>    netlink_rcv_skb+0x54/0x100
>    genl_rcv+0x24/0x40
>    netlink_unicast+0x1fc/0x2d0
>    netlink_sendmsg+0x1e4/0x410
>    __sock_sendmsg+0x38/0x60
>    ? sockfd_lookup_light+0x12/0x60
>    __sys_sendto+0x105/0x160
>    ? __count_memcg_events+0x53/0xe0
>    ? handle_mm_fault+0x100/0x220
>    ? do_user_addr_fault+0x40d/0x620
>    __x64_sys_sendto+0x20/0x30
>    do_syscall_64+0x4c/0x100
>    entry_SYSCALL_64_after_hwframe+0x4b/0x53
>   RIP: 0033:0x7fdfa6c66b57
>   Code: ...
>   RSP: 002b:00007ffeace22998 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
>   RAX: ffffffffffffffda RBX: 000055a498608350 RCX: 00007fdfa6c66b57
>   RDX: 000000000000006c RSI: 000055a498608350 RDI: 0000000000000003
>   RBP: 00007ffeace229c0 R08: 00007fdfa6d35200 R09: 000000000000000c
>   R10: 0000000000000000 R11: 0000000000000202 R12: 000055a4986082a0
>   R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffeace233f3
>    </TASK>
>   Modules linked in: ...
>   CR2: 00000000000000b8
>
> Fixes: 62111654481d ("vdpa/mlx5: Postpone MR deletion")
> Signed-off-by: Dragos Tatulea <dtatulea@...dia.com>

Acked-by: Jason Wang <jasowang@...hat.com>

Thanks