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| author | Hao Ge <hao.ge@linux.dev> | 2026-05-06 10:22:56 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-05-28 21:31:59 -0700 |
| commit | 29cdf3bb9cd165136fd0c3a06d901a4c8d80b6b3 (patch) | |
| tree | 196e6d17f0f0821388ba9366087bbbeced048e65 /mm | |
| parent | 546ba99e104c91abcd47a18253176937d51420c5 (diff) | |
| download | linux-next-history-29cdf3bb9cd165136fd0c3a06d901a4c8d80b6b3.tar.gz | |
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/20260506022256.32664-1-hao.ge@linux.dev
Signed-off-by: Hao Ge <hao.ge@linux.dev>
Suggested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/page_alloc.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 97cb958205923..e47679e7a9dbc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1246,7 +1246,7 @@ void __clear_page_tag_ref(struct page *page) /* Should be called only if mem_alloc_profiling_enabled() */ static noinline void __pgalloc_tag_add(struct page *page, struct task_struct *task, - unsigned int nr) + unsigned int nr, gfp_t gfp_flags) { union pgtag_ref_handle handle; union codetag_ref ref; @@ -1260,17 +1260,17 @@ void __pgalloc_tag_add(struct page *page, struct task_struct *task, * page_ext is not available yet, record the pfn so we can * clear the tag ref later when page_ext is initialized. */ - alloc_tag_add_early_pfn(page_to_pfn(page)); + alloc_tag_add_early_pfn(page_to_pfn(page), gfp_flags); if (task->alloc_tag) alloc_tag_set_inaccurate(task->alloc_tag); } } static inline void pgalloc_tag_add(struct page *page, struct task_struct *task, - unsigned int nr) + unsigned int nr, gfp_t gfp_flags) { if (mem_alloc_profiling_enabled()) - __pgalloc_tag_add(page, task, nr); + __pgalloc_tag_add(page, task, nr, gfp_flags); } /* Should be called only if mem_alloc_profiling_enabled() */ @@ -1303,7 +1303,7 @@ static inline void pgalloc_tag_sub_pages(struct alloc_tag *tag, unsigned int nr) #else /* CONFIG_MEM_ALLOC_PROFILING */ static inline void pgalloc_tag_add(struct page *page, struct task_struct *task, - unsigned int nr) {} + unsigned int nr, gfp_t gfp_flags) {} static inline void pgalloc_tag_sub(struct page *page, unsigned int nr) {} static inline void pgalloc_tag_sub_pages(struct alloc_tag *tag, unsigned int nr) {} @@ -1858,7 +1858,7 @@ inline void post_alloc_hook(struct page *page, unsigned int order, set_page_owner(page, order, gfp_flags); page_table_check_alloc(page, order); - pgalloc_tag_add(page, current, 1 << order); + pgalloc_tag_add(page, current, 1 << order, gfp_flags); } static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags, |