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Subject: Re: WARNING: AMDGPU DRM warning in 5.11.9
To:     linux-kernel@vger.kernel.org
References: <CAK2bqVJ+=nHTK-hnUC=qL1mcOvHWTCwDMYPBKJp77QCbBvBGGw@mail.gmail.com>
From:   Ilkka Prusi <ilkka.prusi@pp.inet.fi>
Message-ID: <a38a3c04-4ac8-01a6-da69-a2bdaa54f61d@pp.inet.fi>
Date:   Thu, 25 Mar 2021 07:57:33 +0200
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On 24.3.2021 16.16, Chris Rankin wrote:
> Hi,
> 
> Theee warnings ares not present in my dmesg log from 5.11.8:
> 
> [   43.390159] ------------[ cut here ]------------
> [   43.393574] WARNING: CPU: 2 PID: 1268 at
> drivers/gpu/drm/ttm/ttm_bo.c:517 ttm_bo_release+0x172/0x282 [ttm]
> [   43.401940] Modules linked in: nf_nat_ftp nf_conntrack_ftp cfg80211

Changing WARN_ON to WARN_ON_ONCE in drivers/gpu/drm/ttm/ttm_bo.c 
ttm_bo_release() reduces the flood of messages into single splat.

This warning appears to come from 57fcd550eb15bce ("drm/ttm: Warn on 
pinning without holding a reference)" and reverting it might be one choice.


> 
> There are others, but I am assuming there is a common cause here.
> 
> Cheers,
> Chris
> 

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index a76eb2c14e8c..50b53355b265 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -514,7 +514,7 @@ static void ttm_bo_release(struct kref *kref)
                  * shrinkers, now that they are queued for
                  * destruction.
                  */
-               if (WARN_ON(bo->pin_count)) {
+               if (WARN_ON_ONCE(bo->pin_count)) {
                         bo->pin_count = 0;
                         ttm_bo_del_from_lru(bo);
                         ttm_bo_add_mem_to_lru(bo, &bo->mem);


--
  - Ilkka