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From:   Alex Deucher <alexdeucher@gmail.com>
Date:   Tue, 23 Mar 2021 10:56:21 -0400
Message-ID: <CADnq5_OLBjUbwxUptPk17XMHarThXj7GDYkgYZOPcd_GOJH1XQ@mail.gmail.com>
Subject: Re: [PATCH] drm/amdkfd: Fix cat debugfs hang_hws file causes system
 crash bug
To:     Qu Huang <jinsdb@126.com>
Cc:     "Kuehling, Felix" <Felix.Kuehling@amd.com>,
        "Deucher, Alexander" <alexander.deucher@amd.com>,
        Christian Koenig <christian.koenig@amd.com>,
        Dave Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Maling list - DRI developers 
        <dri-devel@lists.freedesktop.org>,
        amd-gfx list <amd-gfx@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>
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Precedence: bulk

Applied.  Thanks!

Alex

On Sun, Mar 21, 2021 at 5:33 AM Qu Huang <jinsdb@126.com> wrote:
>
> Here is the system crash log:
> [ 1272.884438] BUG: unable to handle kernel NULL pointer dereference at
> (null)
> [ 1272.884444] IP: [<          (null)>]           (null)
> [ 1272.884447] PGD 825b09067 PUD 8267c8067 PMD 0
> [ 1272.884452] Oops: 0010 [#1] SMP
> [ 1272.884509] CPU: 13 PID: 3485 Comm: cat Kdump: loaded Tainted: G
> [ 1272.884515] task: ffff9a38dbd4d140 ti: ffff9a37cd3b8000 task.ti:
> ffff9a37cd3b8000
> [ 1272.884517] RIP: 0010:[<0000000000000000>]  [<          (null)>]
> (null)
> [ 1272.884520] RSP: 0018:ffff9a37cd3bbe68  EFLAGS: 00010203
> [ 1272.884522] RAX: 0000000000000000 RBX: 0000000000000000 RCX:
> 0000000000014d5f
> [ 1272.884524] RDX: fffffffffffffff4 RSI: 0000000000000001 RDI:
> ffff9a38aca4d200
> [ 1272.884526] RBP: ffff9a37cd3bbed0 R08: ffff9a38dcd5f1a0 R09:
> ffff9a31ffc07300
> [ 1272.884527] R10: ffff9a31ffc07300 R11: ffffffffaddd5e9d R12:
> ffff9a38b4e0fb00
> [ 1272.884529] R13: 0000000000000001 R14: ffff9a37cd3bbf18 R15:
> ffff9a38aca4d200
> [ 1272.884532] FS:  00007feccaa67740(0000) GS:ffff9a38dcd40000(0000)
> knlGS:0000000000000000
> [ 1272.884534] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 1272.884536] CR2: 0000000000000000 CR3: 00000008267c0000 CR4:
> 00000000003407e0
> [ 1272.884537] Call Trace:
> [ 1272.884544]  [<ffffffffade68940>] ? seq_read+0x130/0x440
> [ 1272.884548]  [<ffffffffade40f8f>] vfs_read+0x9f/0x170
> [ 1272.884552]  [<ffffffffade41e4f>] SyS_read+0x7f/0xf0
> [ 1272.884557]  [<ffffffffae374ddb>] system_call_fastpath+0x22/0x27
> [ 1272.884558] Code:  Bad RIP value.
> [ 1272.884562] RIP  [<          (null)>]           (null)
> [ 1272.884564]  RSP <ffff9a37cd3bbe68>
> [ 1272.884566] CR2: 0000000000000000
>
> Signed-off-by: Qu Huang <jinsdb@126.com>
> ---
>  drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c b/drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c
> index 511712c..673d5e3 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c
> @@ -33,6 +33,11 @@ static int kfd_debugfs_open(struct inode *inode, struct file *file)
>
>         return single_open(file, show, NULL);
>  }
> +static int kfd_debugfs_hang_hws_read(struct seq_file *m, void *data)
> +{
> +       seq_printf(m, "echo gpu_id > hang_hws\n");
> +       return 0;
> +}
>
>  static ssize_t kfd_debugfs_hang_hws_write(struct file *file,
>         const char __user *user_buf, size_t size, loff_t *ppos)
> @@ -94,7 +99,7 @@ void kfd_debugfs_init(void)
>         debugfs_create_file("rls", S_IFREG | 0444, debugfs_root,
>                             kfd_debugfs_rls_by_device, &kfd_debugfs_fops);
>         debugfs_create_file("hang_hws", S_IFREG | 0200, debugfs_root,
> -                           NULL, &kfd_debugfs_hang_hws_fops);
> +                           kfd_debugfs_hang_hws_read, &kfd_debugfs_hang_hws_fops);
>  }
>
>  void kfd_debugfs_fini(void)
> --
> 1.8.3.1
>
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