[RFC PATCH 4/4] mm/percpu: stop unmapping the CPU that failed to map
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From: Hao Ge <hao.ge@linux.dev>
Date: 2026-10-09 06:36:28
Also in:
linux-mm, lkml
Subsystem:
memory management, per-cpu memory allocator, the rest · Maintainers:
Andrew Morton, Dennis Zhou, Tejun Heo, Christoph Lameter, Linus Torvalds
__pcpu_map_pages() clears the PTEs it installed when it fails, so pcpu_map_pages() only has to tear down the CPUs it mapped before the failing one. Signed-off-by: Hao Ge <hao.ge@linux.dev> --- mm/percpu-vm.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c
index 509d8901835c..59d3a336a6bd 100644
--- a/mm/percpu-vm.c
+++ b/mm/percpu-vm.c@@ -252,10 +252,11 @@ static int pcpu_map_pages(struct pcpu_chunk *chunk, struct page **pages, return 0; err: for_each_possible_cpu(tcpu) { - __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start), - page_end - page_start); + /* The failing CPU's partial mapping undoes itself */ if (tcpu == cpu) break; + __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start), + page_end - page_start); } pcpu_post_unmap_tlb_flush(chunk, page_start, page_end); return err;
--
2.25.1