-----Original Message-----
From: dri-devel <[email protected]> On Behalf
Of Matthew Auld
Sent: Tuesday, October 6, 2026 4:37 PM
To: [email protected]
Cc: [email protected]; Shashiko
<[email protected]>; Paneer Selvam, Arunpravin
<[email protected]>; Joel Fernandes
<[email protected]>; [email protected]
Subject: [PATCH] gpu/buddy: do not pass caller list to
__alloc_contig_try_harder()
If the caller passes a non-empty blocks list,
__alloc_contig_try_harder() unconditionally frees it on failure or
during retry.
Pass the local allocated list instead and only splice it onto the
caller's list upon success.
Assisted-by: LLM
Reported-by: Shashiko <[email protected]>
Closes:
https://sashiko.dev/#/bug/linux-fa721daf-7333-48b5-a26b-624c7f5791d7
Fixes: 0a1844bf0b53 ("drm/buddy: Improve contiguous memory allocation")
Signed-off-by: Matthew Auld <[email protected]>
Cc: Arunpravin Paneer Selvam <[email protected]>
Cc: Joel Fernandes <[email protected]>
Cc: <[email protected]>
---
drivers/gpu/buddy.c | 20 ++++++++++++++------
drivers/gpu/tests/gpu_buddy_test.c | 9 +++++++++
2 files changed, 23 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/buddy.c b/drivers/gpu/buddy.c index
2f2aaadafe35..a86f454fbb40 100644
--- a/drivers/gpu/buddy.c
+++ b/drivers/gpu/buddy.c
@@ -2022,10 +2022,16 @@ int gpu_buddy_alloc_blocks(struct gpu_buddy *mm,
if (order > mm->max_order || size > mm->size) {
if ((flags & GPU_BUDDY_CONTIGUOUS_ALLOCATION) &&
- !(flags & GPU_BUDDY_RANGE_ALLOCATION))
- return __alloc_contig_try_harder(mm,
original_size,
- original_min_size,
- flags, blocks);
+ !(flags & GPU_BUDDY_RANGE_ALLOCATION)) {
+ err = __alloc_contig_try_harder(mm,
original_size,
+ original_min_size,
+ flags,
&allocated);
+ if (err)
+ return err;
+
+ list_splice_tail(&allocated, blocks);
+ return 0;
+ }
return -EINVAL;
}
@@ -2064,9 +2070,11 @@ int gpu_buddy_alloc_blocks(struct gpu_buddy *mm,
original_size,
original_min_size,
flags,
- blocks);
- if (!err)
+ &allocated);
+ if (!err) {
+ list_splice_tail(&allocated, blocks);
return 0;
+ }
if (err != -ENOSPC)
return err;
goto err_free;
diff --git a/drivers/gpu/tests/gpu_buddy_test.c
b/drivers/gpu/tests/gpu_buddy_test.c
index b75d32ca6ca0..2c6f1da1a6d1 100644
--- a/drivers/gpu/tests/gpu_buddy_test.c
+++ b/drivers/gpu/tests/gpu_buddy_test.c
@@ -1235,6 +1235,15 @@ static void
gpu_test_buddy_alloc_contiguous(struct kunit *test)
GPU_BUDDY_CONTIGUOUS_ALLOCATION),
"buddy_alloc hit an error
size=%lu\n", 2 * ps);
+ /*
+ * A failed contiguous allocation with a non-empty blocks list
+ * must NOT corrupt or free pre-existing blocks.
+ */
+ KUNIT_EXPECT_TRUE(test, gpu_buddy_alloc_blocks(&mm, 0, mm_size,
+ 3 * ps, ps,
&allocated,
+ GPU_BUDDY_CONTIGUOUS_ALLOCATION));
+ KUNIT_EXPECT_FALSE(test, list_empty(&allocated));
+
gpu_buddy_free_list(&mm, &left, 0);
KUNIT_ASSERT_FALSE_MSG(test, gpu_buddy_alloc_blocks(&mm, 0,
mm_size,
3 * ps,
ps, &allocated,
--
2.55.0
