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<p>Hi Rodrigo,<br>
</p>
<div class="moz-cite-prefix">On 6/26/2024 5:24 PM, Rodrigo Vivi
wrote:<br>
</div>
<blockquote type="cite" cite="mid:ZnwylM64-5HqQr4R@intel.com">
<pre class="moz-quote-pre" wrap="">On Wed, Jun 26, 2024 at 04:33:18PM +0200, Nirmoy Das wrote:
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">We report object allocation failures to userspace with ENOMEM
so add __GFP_NOWARN to remove superfluous oom warnings.
Closes: <a class="moz-txt-link-freetext" href="https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/4936">https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/4936</a>
Cc: Andi Shyti <a class="moz-txt-link-rfc2396E" href="mailto:andi.shyti@linux.intel.com"><andi.shyti@linux.intel.com></a>
Signed-off-by: Nirmoy Das <a class="moz-txt-link-rfc2396E" href="mailto:nirmoy.das@intel.com"><nirmoy.das@intel.com></a>
---
drivers/gpu/drm/i915/i915_scatterlist.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_scatterlist.c b/drivers/gpu/drm/i915/i915_scatterlist.c
index e93d2538f298..4d830740946d 100644
--- a/drivers/gpu/drm/i915/i915_scatterlist.c
+++ b/drivers/gpu/drm/i915/i915_scatterlist.c
@@ -90,7 +90,7 @@ struct i915_refct_sgt *i915_rsgt_from_mm_node(const struct drm_mm_node *node,
GEM_BUG_ON(!max_segment);
- rsgt = kmalloc(sizeof(*rsgt), GFP_KERNEL);
+ rsgt = kmalloc(sizeof(*rsgt), GFP_KERNEL | __GFP_NOWARN);
if (!rsgt)
return ERR_PTR(-ENOMEM);
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">
is it really safe?
I don't believe we can guarantee a good fallback plan here if allocation fails.
__i915_refct_sgt_init
might end up in a null dereference, no?!</pre>
</blockquote>
<p>Kernel is now returning <span style="white-space: pre-wrap">ENOMEM and also throwing a oom warning stack. With </span><span style="white-space: pre-wrap">__GFP_NOWARN</span></p>
<p><span style="white-space: pre-wrap">the oom warning stack won't be there in the dmesg but userspace will still get </span><span style="white-space: pre-wrap">ENOMEM as expected.</span></p>
<p><span style="white-space: pre-wrap">Let me know if got your question correctly.</span></p>
<p><span style="white-space: pre-wrap">
</span></p>
<p><span style="white-space: pre-wrap">Regards,</span></p>
<p><span style="white-space: pre-wrap">Nirmoy
</span></p>
<p><span style="white-space: pre-wrap">
</span></p>
<blockquote type="cite" cite="mid:ZnwylM64-5HqQr4R@intel.com">
<pre class="moz-quote-pre" wrap="">
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">
@@ -104,7 +104,7 @@ struct i915_refct_sgt *i915_rsgt_from_mm_node(const struct drm_mm_node *node,
}
if (sg_alloc_table(st, DIV_ROUND_UP_ULL(node->size, segment_pages),
- GFP_KERNEL)) {
+ GFP_KERNEL | __GFP_NOWARN)) {
i915_refct_sgt_put(rsgt);
return ERR_PTR(-ENOMEM);
}
@@ -178,7 +178,7 @@ struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res,
GEM_BUG_ON(list_empty(blocks));
GEM_BUG_ON(!max_segment);
- rsgt = kmalloc(sizeof(*rsgt), GFP_KERNEL);
+ rsgt = kmalloc(sizeof(*rsgt), GFP_KERNEL | __GFP_NOWARN);
if (!rsgt)
return ERR_PTR(-ENOMEM);
@@ -190,7 +190,7 @@ struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res,
return ERR_PTR(-E2BIG);
}
- if (sg_alloc_table(st, PFN_UP(res->size), GFP_KERNEL)) {
+ if (sg_alloc_table(st, PFN_UP(res->size), GFP_KERNEL | __GFP_NOWARN)) {
i915_refct_sgt_put(rsgt);
return ERR_PTR(-ENOMEM);
}
--
2.42.0
</pre>
</blockquote>
</blockquote>
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