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89b1b79c30
In pcpu_create_chunk(), nr_pages is the total contiguous backing allocation, i.e., nr_units * pcpu_unit_pages, but pcpu_chunk_populated() uses it to set chunk->populated, whose size is pcpu_unit_pages, bitmap. Since bit N in chunk->populated means page offset N inside every unit is backed. When nr_units > 1, the function writes beyond chunk->populated. Fix it by using chunk->nr_pages. It also fixes the global pcpu_nr_empty_pop_pages accounting, since pcpu_balance_free() only iterates up to chunk->nr_pages. Commita63d4ac4ab("percpu: make percpu-km set chunk->populated bitmap properly") introduced the bitmap overflow issue. Later, commitb539b87fed("percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated") added pcpu_nr_empty_pop_pages and caused the accounting issue. Link: https://lore.kernel.org/20260709-fix-pcpu_create_chunk-in-percpu-km-v1-1-1f64745a84cc@nvidia.com Fixes:a63d4ac4ab("percpu: make percpu-km set chunk->populated bitmap properly") Reported-by: Sashiko <sashiko-bot@kernel.org> Closes: https://sashiko.dev/#/patchset/20260703-keep-subpage-private-zero-at-free-v2-0-2970fe777dd6%40nvidia.com?part=1 Assisted-by: Codex:GPT-5 Signed-off-by: Zi Yan <ziy@nvidia.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Tejun Heo <tj@kernel.org> Cc: Zi Yan <ziy@nvidia.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
130 lines
3.2 KiB
130 lines
3.2 KiB