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| author | David Gow <davidgow@google.com> | 2023-03-29 08:55:32 +0200 |
|---|---|---|
| committer | Christian König <christian.koenig@amd.com> | 2023-03-29 17:14:07 +0200 |
| commit | 4453545b5b4c3eff941f69a5530f916d899db025 (patch) | |
| tree | c058f4aff2e8be8e3f0ab7a28055814fc21bd841 /drivers/gpu/drm/drm_buddy.c | |
| parent | drm/nouveau/kms: Fix backlight registration (diff) | |
| download | linux-4453545b5b4c3eff941f69a5530f916d899db025.tar.xz linux-4453545b5b4c3eff941f69a5530f916d899db025.zip | |
drm: buddy_allocator: Fix buddy allocator init on 32-bit systems
The drm buddy allocator tests were broken on 32-bit systems, as
rounddown_pow_of_two() takes a long, and the buddy allocator handles
64-bit sizes even on 32-bit systems.
This can be reproduced with the drm_buddy_allocator KUnit tests on i386:
./tools/testing/kunit/kunit.py run --arch i386 \
--kunitconfig ./drivers/gpu/drm/tests drm_buddy
(It results in kernel BUG_ON() when too many blocks are created, due to
the block size being too small.)
This was independently uncovered (and fixed) by Luís Mendes, whose patch
added a new u64 variant of rounddown_pow_of_two(). This version instead
recalculates the size based on the order.
Reported-by: Luís Mendes <luis.p.mendes@gmail.com>
Link: https://lore.kernel.org/lkml/CAEzXK1oghXAB_KpKpm=-CviDQbNaH0qfgYTSSjZgvvyj4U78AA@mail.gmail.com/T/
Signed-off-by: David Gow <davidgow@google.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Arunpravin Paneer Selvam <arunpravin.paneerselvam@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230329065532.2122295-1-davidgow@google.com
Signed-off-by: Christian König <christian.koenig@amd.com>
Diffstat (limited to 'drivers/gpu/drm/drm_buddy.c')
| -rw-r--r-- | drivers/gpu/drm/drm_buddy.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c index 3d1f50f481cf..7098f125b54a 100644 --- a/drivers/gpu/drm/drm_buddy.c +++ b/drivers/gpu/drm/drm_buddy.c @@ -146,8 +146,8 @@ int drm_buddy_init(struct drm_buddy *mm, u64 size, u64 chunk_size) unsigned int order; u64 root_size; - root_size = rounddown_pow_of_two(size); - order = ilog2(root_size) - ilog2(chunk_size); + order = ilog2(size) - ilog2(chunk_size); + root_size = chunk_size << order; root = drm_block_alloc(mm, NULL, order, offset); if (!root) |