linux-kernel - Re: [PATCH] drm/radeon: don't evict if not initialized

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Message-ID: <CAA5qM4DCN1PQqyWxH3o27ixAkbWHf3so12Ba7=9gxUpdk2wkGA@mail.gmail.com>
Date:   Sun, 21 Mar 2021 11:20:38 -0400
From:   Tong Zhang <ztong0001@...il.com>
To:     Christian König <christian.koenig@....com>
Cc:     Alex Deucher <alexander.deucher@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, amd-gfx@...ts.freedesktop.org,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/radeon: don't evict if not initialized

Thanks,
Fixed as suggested and sent as v2.
- Tong

On Sun, Mar 21, 2021 at 9:26 AM Christian König
<christian.koenig@....com> wrote:
>
>
>
> Am 20.03.21 um 21:10 schrieb Tong Zhang:
> > TTM_PL_VRAM may not initialized at all when calling
> > radeon_bo_evict_vram(). We need to check before doing eviction.
> >
> > [    2.160837] BUG: kernel NULL pointer dereference, address: 0000000000000020
> > [    2.161212] #PF: supervisor read access in kernel mode
> > [    2.161490] #PF: error_code(0x0000) - not-present page
> > [    2.161767] PGD 0 P4D 0
> > [    2.163088] RIP: 0010:ttm_resource_manager_evict_all+0x70/0x1c0 [ttm]
> > [    2.168506] Call Trace:
> > [    2.168641]  radeon_bo_evict_vram+0x1c/0x20 [radeon]
> > [    2.168936]  radeon_device_fini+0x28/0xf9 [radeon]
> > [    2.169224]  radeon_driver_unload_kms+0x44/0xa0 [radeon]
> > [    2.169534]  radeon_driver_load_kms+0x174/0x210 [radeon]
> > [    2.169843]  drm_dev_register+0xd9/0x1c0 [drm]
> > [    2.170104]  radeon_pci_probe+0x117/0x1a0 [radeon]
> >
> > Signed-off-by: Tong Zhang <ztong0001@...il.com>
> > ---
> >   drivers/gpu/drm/radeon/radeon_object.c | 4 +++-
> >   1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c
> > index 9b81786782de..04e9a8118b0e 100644
> > --- a/drivers/gpu/drm/radeon/radeon_object.c
> > +++ b/drivers/gpu/drm/radeon/radeon_object.c
> > @@ -384,7 +384,9 @@ int radeon_bo_evict_vram(struct radeon_device *rdev)
> >       }
> >   #endif
> >       man = ttm_manager_type(bdev, TTM_PL_VRAM);
> > -     return ttm_resource_manager_evict_all(bdev, man);
> > +     if (man)
> > +             return ttm_resource_manager_evict_all(bdev, man);
> > +     return 0;
>
> You should probably code this the other way around, e.g.
>
> If (!man)
>      return 0;
> ...
>
> Apart from that looks good to me.
>
> Christian.
>
> >   }
> >
> >   void radeon_bo_force_delete(struct radeon_device *rdev)
>