On 2/21/24 20:40, Suren Baghdasaryan wrote: > When a high-order page is split into smaller ones, each newly split > page should get its codetag. The original codetag is reused for these > pages but it's recorded as 0-byte allocation because original codetag > already accounts for the original high-order allocated page.
This was v3 but then you refactored (for the better) so the commit log could reflect it? > Signed-off-by: Suren Baghdasaryan <[email protected]> I was going to R-b, but now I recalled the trickiness of __free_pages() for non-compound pages if it loses the race to a speculative reference. Will the codetag handling work fine there? > --- > include/linux/pgalloc_tag.h | 30 ++++++++++++++++++++++++++++++ > mm/huge_memory.c | 2 ++ > mm/page_alloc.c | 2 ++ > 3 files changed, 34 insertions(+) > > diff --git a/include/linux/pgalloc_tag.h b/include/linux/pgalloc_tag.h > index b49ab955300f..9e6ad8e0e4aa 100644 > --- a/include/linux/pgalloc_tag.h > +++ b/include/linux/pgalloc_tag.h > @@ -67,11 +67,41 @@ static inline void pgalloc_tag_sub(struct page *page, > unsigned int order) > } > } > > +static inline void pgalloc_tag_split(struct page *page, unsigned int nr) > +{ > + int i; > + struct page_ext *page_ext; > + union codetag_ref *ref; > + struct alloc_tag *tag; > + > + if (!mem_alloc_profiling_enabled()) > + return; > + > + page_ext = page_ext_get(page); > + if (unlikely(!page_ext)) > + return; > + > + ref = codetag_ref_from_page_ext(page_ext); > + if (!ref->ct) > + goto out; > + > + tag = ct_to_alloc_tag(ref->ct); > + page_ext = page_ext_next(page_ext); > + for (i = 1; i < nr; i++) { > + /* Set new reference to point to the original tag */ > + alloc_tag_ref_set(codetag_ref_from_page_ext(page_ext), tag); > + page_ext = page_ext_next(page_ext); > + } > +out: > + page_ext_put(page_ext); > +} > + > #else /* CONFIG_MEM_ALLOC_PROFILING */ > > static inline void pgalloc_tag_add(struct page *page, struct task_struct > *task, > unsigned int order) {} > static inline void pgalloc_tag_sub(struct page *page, unsigned int order) {} > +static inline void pgalloc_tag_split(struct page *page, unsigned int nr) {} > > #endif /* CONFIG_MEM_ALLOC_PROFILING */ > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 94c958f7ebb5..86daae671319 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -38,6 +38,7 @@ > #include <linux/sched/sysctl.h> > #include <linux/memory-tiers.h> > #include <linux/compat.h> > +#include <linux/pgalloc_tag.h> > > #include <asm/tlb.h> > #include <asm/pgalloc.h> > @@ -2899,6 +2900,7 @@ static void __split_huge_page(struct page *page, struct > list_head *list, > /* Caller disabled irqs, so they are still disabled here */ > > split_page_owner(head, nr); > + pgalloc_tag_split(head, nr); > > /* See comment in __split_huge_page_tail() */ > if (PageAnon(head)) { > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 58c0e8b948a4..4bc5b4720fee 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2621,6 +2621,7 @@ void split_page(struct page *page, unsigned int order) > for (i = 1; i < (1 << order); i++) > set_page_refcounted(page + i); > split_page_owner(page, 1 << order); > + pgalloc_tag_split(page, 1 << order); > split_page_memcg(page, 1 << order); > } > EXPORT_SYMBOL_GPL(split_page); > @@ -4806,6 +4807,7 @@ static void *make_alloc_exact(unsigned long addr, > unsigned int order, > struct page *last = page + nr; > > split_page_owner(page, 1 << order); > + pgalloc_tag_split(page, 1 << order); > split_page_memcg(page, 1 << order); > while (page < --last) > set_page_refcounted(last);
