From: David Gow <davidgow@xxxxxxxxxx> [ Upstream commit 4453545b5b4c3eff941f69a5530f916d899db025 ] 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@xxxxxxxxx> Link: https://lore.kernel.org/lkml/CAEzXK1oghXAB_KpKpm=-CviDQbNaH0qfgYTSSjZgvvyj4U78AA@xxxxxxxxxxxxxx/T/ Signed-off-by: David Gow <davidgow@xxxxxxxxxx> Acked-by: Christian König <christian.koenig@xxxxxxx> Reviewed-by: Arunpravin Paneer Selvam <arunpravin.paneerselvam@xxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20230329065532.2122295-1-davidgow@xxxxxxxxxx Signed-off-by: Christian König <christian.koenig@xxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/gpu/drm/drm_buddy.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c index 3d1f50f481cfd..7098f125b54a9 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) -- 2.39.2
