Re: [RFC PATCH 4/4] mm/percpu: stop unmapping the CPU that failed to map
flat view
From: Suren Baghdasaryan <surenb@google.com>
Date: 2026-10-13 11:47:00
Also in:
linux-mm, lkml
On Fri, Oct 9, 2026 at 10:36 AM Hao Ge [off-list ref] wrote:
__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>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
quoted hunk ↗ jump to hunk
--- 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