[PATCH] drm/amdgpu: Fix incorrect return value

[Chai, Thomas]

[AMD Official Use Only - General]

-----------------
Best Regards,
Thomas

-----Original Message-----
From: Zhou1, Tao <Tao.Zhou1 at amd.com>
Sent: Wednesday, April 3, 2024 6:36 PM
To: Chai, Thomas <YiPeng.Chai at amd.com>; amd-gfx at lists.freedesktop.org
Cc: Zhang, Hawking <Hawking.Zhang at amd.com>; Li, Candice <Candice.Li at amd.com>; Wang, Yang(Kevin) <KevinYang.Wang at amd.com>; Yang, Stanley <Stanley.Yang at amd.com>
Subject: RE: [PATCH] drm/amdgpu: Fix incorrect return value

[AMD Official Use Only - General]

> -----Original Message-----
> From: Chai, Thomas <YiPeng.Chai at amd.com>
> Sent: Wednesday, April 3, 2024 3:07 PM
> To: amd-gfx at lists.freedesktop.org
> Cc: Chai, Thomas <YiPeng.Chai at amd.com>; Zhang, Hawking
> <Hawking.Zhang at amd.com>; Zhou1, Tao <Tao.Zhou1 at amd.com>; Li, Candice
> <Candice.Li at amd.com>; Wang, Yang(Kevin) <KevinYang.Wang at amd.com>;
> Yang, Stanley <Stanley.Yang at amd.com>; Chai, Thomas
> <YiPeng.Chai at amd.com>
> Subject: [PATCH] drm/amdgpu: Fix incorrect return value
>
> [Why]
>   After calling amdgpu_vram_mgr_reserve_range multiple times with the
> same address, calling amdgpu_vram_mgr_query_page_status will always
> return - EBUSY.

>[Tao] could you explain why we call amdgpu_vram_mgr_reserve_range multiple times with the same  address? IIRC, we skip duplicate address before reserve memory.

[Thomas]
   When poison creation interrupt is received, since some poisoning addresses may have been allocated by some processes, reserving these memories will fail.
These memory will be tried to reserve again after killing the poisoned process in the subsequent poisoning consumption interrupt handler.
so amdgpu_vram_mgr_reserve_range needs to be called multiple times with the same address.

>   From the second call to amdgpu_vram_mgr_reserve_range, the same
> address will be added to the reservations_pending list again and is
> never moved to the reserved_pages list because the address had been reserved.
>
> [How]
>   First add the address status check before calling
> amdgpu_vram_mgr_do_reserve, if the address is already reserved, do
> nothing; If the address is already in the reservations_pending list,
> directly reserve memory; only add new nodes for the addresses that are
> not in the reserved_pages list and reservations_pending list.
>
> Signed-off-by: YiPeng Chai <YiPeng.Chai at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 28
> +++++++++++++-------
>  1 file changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index 1e36c428d254..0bf3f4092900 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -317,7 +317,6 @@ static void amdgpu_vram_mgr_do_reserve(struct
> ttm_resource_manager *man)
>
>               dev_dbg(adev->dev, "Reservation 0x%llx - %lld, Succeeded\n",
>                       rsv->start, rsv->size);
> -
>               vis_usage = amdgpu_vram_mgr_vis_size(adev, block);
>               atomic64_add(vis_usage, &mgr->vis_usage);
>               spin_lock(&man->bdev->lru_lock); @@ -340,19 +339,30 @@
> int amdgpu_vram_mgr_reserve_range(struct
> amdgpu_vram_mgr *mgr,
>                                 uint64_t start, uint64_t size)  {
>       struct amdgpu_vram_reservation *rsv;
> +     int ret = 0;
>
> -     rsv = kzalloc(sizeof(*rsv), GFP_KERNEL);
> -     if (!rsv)
> -             return -ENOMEM;
> +     ret = amdgpu_vram_mgr_query_page_status(mgr, start);
> +     if (!ret)
> +             return 0;
> +
> +     if (ret == -ENOENT) {
> +             rsv = kzalloc(sizeof(*rsv), GFP_KERNEL);
> +             if (!rsv)
> +                     return -ENOMEM;
>
> -     INIT_LIST_HEAD(&rsv->allocated);
> -     INIT_LIST_HEAD(&rsv->blocks);
> +             INIT_LIST_HEAD(&rsv->allocated);
> +             INIT_LIST_HEAD(&rsv->blocks);
>
> -     rsv->start = start;
> -     rsv->size = size;
> +             rsv->start = start;
> +             rsv->size = size;
> +
> +             mutex_lock(&mgr->lock);
> +             list_add_tail(&rsv->blocks, &mgr->reservations_pending);
> +             mutex_unlock(&mgr->lock);
> +
> +     }
>
>       mutex_lock(&mgr->lock);
> -     list_add_tail(&rsv->blocks, &mgr->reservations_pending);
>       amdgpu_vram_mgr_do_reserve(&mgr->manager);
>       mutex_unlock(&mgr->lock);
>
> --
> 2.34.1