Re: 回复: [PATCH] drm/ttm: Put BO in its memory manager's lru list

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Yeah, that should probably be the right one.

Christian.

Am 12.01.22 um 03:19 schrieb Chen, Guchun:
[Public]

Hi Christian,

My BAD, I checked that discussion history of this just now. So If I read it correctly, the double check at a different place to skip evict is: " drm/ttm: Double check mem_type of BO while eviction"? It is in 5.16 kernel.

Regards,
Guchun

-----Original Message-----
From: Christian König <ckoenig.leichtzumerken@xxxxxxxxx>
Sent: Tuesday, January 11, 2022 7:27 PM
To: Chen, Guchun <Guchun.Chen@xxxxxxx>; Pan, Xinhui <Xinhui.Pan@xxxxxxx>; Koenig, Christian <Christian.Koenig@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Subject: Re: 回复: [PATCH] drm/ttm: Put BO in its memory manager's lru list

IIRC we have completely dropped this patch in favor of a check at a different place.

Regards,
Christian.

Am 11.01.22 um 09:47 schrieb Chen, Guchun:
[Public]

Hi Christian,

Looks this patch still missed in 5.16 kernel. Is it intentional?
https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.
kernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Ftorvalds%2Flinux.git%2
Ftree%2Fdrivers%2Fgpu%2Fdrm%2Fttm%2Fttm_bo.c%3Fh%3Dv5.16&amp;data=04%7
C01%7CGuchun.Chen%40amd.com%7Cf3b7f4971dc8405b0c2908d9d4f55547%7C3dd89
61fe4884e608e11a82d994e183d%7C0%7C0%7C637774972434004088%7CUnknown%7CT
WFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI
6Mn0%3D%7C3000&amp;sdata=vbuBPHO40J2HGt7abzfzC0nC1DQa62qal5S6TXBRj4w%3
D&amp;reserved=0

Regards,
Guchun

-----Original Message-----
From: amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of
Pan, Xinhui
Sent: Tuesday, November 9, 2021 9:16 PM
To: Koenig, Christian <Christian.Koenig@xxxxxxx>;
amd-gfx@xxxxxxxxxxxxxxxxxxxxx
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Subject: 回复: 回复: [PATCH] drm/ttm: Put BO in its memory manager's lru
list

[AMD Official Use Only]

[AMD Official Use Only]

Actually this patch does not totally fix the mismatch of lru list with mem_type as mem_type is changed in ->move() and lru list is changed after that.

During this small period, another eviction could still happed and evict this mismatched BO from sMam(say, its lru list is on vram domain) to sMem.
________________________________________
发件人: Pan, Xinhui <Xinhui.Pan@xxxxxxx>
发送时间: 2021年11月9日 21:05
收件人: Koenig, Christian; amd-gfx@xxxxxxxxxxxxxxxxxxxxx
抄送: dri-devel@xxxxxxxxxxxxxxxxxxxxx
主题: 回复: 回复: [PATCH] drm/ttm: Put BO in its memory manager's lru list

Yes, a stable tag is needed. vulkan guys say 5.14 hit this issue too.

I think that amdgpu_bo_move() does support copy from sysMem to sysMem correctly.
maybe something below is needed.
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index c83ef42ca702..aa63ae7ddf1e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -485,7 +485,8 @@ static int amdgpu_bo_move(struct ttm_buffer_object *bo, bool evict,
          }
          if (old_mem->mem_type == TTM_PL_SYSTEM &&
              (new_mem->mem_type == TTM_PL_TT ||
-            new_mem->mem_type == AMDGPU_PL_PREEMPT)) {
+            new_mem->mem_type == AMDGPU_PL_PREEMPT ||
+            new_mem->mem_type == TTM_PL_SYSTEM)) {
                  ttm_bo_move_null(bo, new_mem);
                  goto out;
          }

otherwise, amdgpu_move_blit() is called to do the system memory copy which use a wrong address.
   206         /* Map only what can't be accessed directly */
   207         if (!tmz && mem->start != AMDGPU_BO_INVALID_OFFSET) {
   208                 *addr = amdgpu_ttm_domain_start(adev, mem->mem_type) +
   209                         mm_cur->start;
   210                 return 0;
   211         }

line 208, *addr is zero. So when amdgpu_copy_buffer submit job with such addr, page fault happens.


________________________________________
发件人: Koenig, Christian <Christian.Koenig@xxxxxxx>
发送时间: 2021年11月9日 20:35
收件人: Pan, Xinhui; amd-gfx@xxxxxxxxxxxxxxxxxxxxx
抄送: dri-devel@xxxxxxxxxxxxxxxxxxxxx
主题: Re: 回复: [PATCH] drm/ttm: Put BO in its memory manager's lru list

Mhm, I'm not sure what the rational behind that is.

Not moving the BO would make things less efficient, but should never cause a crash.

Maybe we should add a CC: stable tag and push it to -fixes instead?

Christian.

Am 09.11.21 um 13:28 schrieb Pan, Xinhui:
[AMD Official Use Only]

I hit vulkan cts test hang with navi23.

dmesg says gmc page fault with address 0x0, 0x1000, 0x2000....
And some debug log also says amdgu copy one BO from system Domain to system Domain which is really weird.
________________________________________
发件人: Koenig, Christian <Christian.Koenig@xxxxxxx>
发送时间: 2021年11月9日 20:20
收件人: Pan, Xinhui; amd-gfx@xxxxxxxxxxxxxxxxxxxxx
抄送: dri-devel@xxxxxxxxxxxxxxxxxxxxx
主题: Re: [PATCH] drm/ttm: Put BO in its memory manager's lru list

Am 09.11.21 um 12:19 schrieb xinhui pan:
After we move BO to a new memory region, we should put it to the new
memory manager's lru list regardless we unlock the resv or not.

Signed-off-by: xinhui pan <xinhui.pan@xxxxxxx>
Interesting find, did you trigger that somehow or did you just
stumbled over it by reading the code?

Patch is Reviewed-by: Christian König <christian.koenig@xxxxxxx>, I
will pick that up for drm-misc-next.

Thanks,
Christian.

---
     drivers/gpu/drm/ttm/ttm_bo.c | 2 ++
     1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c
b/drivers/gpu/drm/ttm/ttm_bo.c index f1367107925b..e307004f0b28
100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -701,6 +701,8 @@ int ttm_mem_evict_first(struct ttm_device *bdev,
         ret = ttm_bo_evict(bo, ctx);
         if (locked)
                 ttm_bo_unreserve(bo);
+     else
+             ttm_bo_move_to_lru_tail_unlocked(bo);

         ttm_bo_put(bo);
         return ret;




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