From 0c3a350d13ce8bb7c3427597819b0dfbc19ba242 Mon Sep 17 00:00:00 2001 From: Hao Ge Date: Thu, 4 Jun 2026 10:40:08 +0800 Subject: mm/alloc_tag: replace fixed-size early PFN array with dynamic linked list Pages allocated before page_ext is available have their codetag left uninitialized. Track these early PFNs and clear their codetag in clear_early_alloc_pfn_tag_refs() to avoid "alloc_tag was not set" warnings when they are freed later. Currently a fixed-size array of 8192 entries is used, with a warning if the limit is exceeded. However, the number of early allocations depends on the number of CPUs and can be larger than 8192. Replace the fixed-size array with a dynamically allocated linked list of pfn_pool structs. Each node is allocated via alloc_page() and mapped to a pfn_pool containing a next pointer, an atomic slot counter, and a PFN array that fills the remainder of the page. The tracking pages themselves are allocated via alloc_page(), which would trigger __pgalloc_tag_add() -> alloc_tag_add_early_pfn() and recurse indefinitely. Introduce __GFP_NO_CODETAG (reuses the %__GFP_NO_OBJ_EXT bit) and pass gfp_flags through pgalloc_tag_add() so that the early path can skip recording allocations that carry this flag. Link: https://lore.kernel.org/20260604024008.46592-1-hao.ge@linux.dev Signed-off-by: Hao Ge Suggested-by: Suren Baghdasaryan Acked-by: Suren Baghdasaryan Cc: Kent Overstreet Signed-off-by: Andrew Morton --- include/linux/alloc_tag.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/alloc_tag.h') diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h index 02de2ede560f..068ba2e77c5d 100644 --- a/include/linux/alloc_tag.h +++ b/include/linux/alloc_tag.h @@ -163,11 +163,11 @@ static inline void alloc_tag_sub_check(union codetag_ref *ref) { WARN_ONCE(ref && !ref->ct, "alloc_tag was not set\n"); } -void alloc_tag_add_early_pfn(unsigned long pfn); +void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t gfp_flags); #else static inline void alloc_tag_add_check(union codetag_ref *ref, struct alloc_tag *tag) {} static inline void alloc_tag_sub_check(union codetag_ref *ref) {} -static inline void alloc_tag_add_early_pfn(unsigned long pfn) {} +static inline void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t gfp_flags) {} #endif /* Caller should verify both ref and tag to be valid */ -- cgit v1.2.3