From 7cf6d940f4032d87d9cfe6b27c0e49e309818e5d Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Tue, 31 Mar 2026 19:37:24 +0800 Subject: [PATCH] mm/sparse: fix preinited section_mem_map clobbering on failure path sparse_init_nid() is careful to leave alone every section whose vmemmap has already been set up by sparse_vmemmap_init_nid_early(); it only clears section_mem_map for the rest: if (!preinited_vmemmap_section(ms)) ms->section_mem_map = 0; A leftover line after that conditional block ms->section_mem_map = 0; was supposed to be deleted but was missed in the failure path, causing the field to be overwritten for all sections when memory allocation fails, effectively destroying the pre-initialization check. Drop the stray assignment so that preinited sections retain their already valid state. Those pre-inited sections (HugeTLB pages) are not activated. However, such failures are extremely rare, so I don't see any major userspace issues. Link: https://lore.kernel.org/20260331113724.2080833-1-songmuchun@bytedance.com Fixes: d65917c42373 ("mm/sparse: allow for alternate vmemmap section init at boot") Signed-off-by: Muchun Song Acked-by: David Hildenbrand (Arm) Reviewed by: Donet Tom Cc: David Hildenbrand Cc: Frank van der Linden Cc: Liam Howlett Cc: Lorenzo Stoakes (Oracle) Cc: Michal Hocko Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/sparse.c | 1 - 1 file changed, 1 deletion(-) diff --git a/mm/sparse.c b/mm/sparse.c index 007fd52c621e..effdac6b0ab1 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -403,7 +403,6 @@ static void __init sparse_init_nid(int nid, unsigned long pnum_begin, ms = __nr_to_section(pnum); if (!preinited_vmemmap_section(ms)) ms->section_mem_map = 0; - ms->section_mem_map = 0; } }