From a0319334a9cc22d408007b444305394d20a553de Mon Sep 17 00:00:00 2001 From: Zi Yan Date: Sun, 20 Sep 2026 22:27:58 -0400 Subject: [PATCH] perf/ring_buffer: stop using PG_private as AUX page high-order marker A high-order AUX page sets PG_private on its first page and stores the order in first_page->private. Stop using PG_private and check first_page->private for AUX page order only in the ring buffer and its users. This is fine because page->private is 0 for order-0 AUX pages, matching the page order. It prepares for a future commit that remove PG_private. No functional change intended. Link: https://lore.kernel.org/20260920-remove-pg_private-v5-2-bb68b6a21869@nvidia.com Signed-off-by: Zi Yan Signed-off-by: Andrew Morton Acked-by: Usama Arif Acked-by: David Hildenbrand (Arm) Assisted-by: LLM Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Namhyung Kim Cc: Thomas Gleixner Cc: Borislav Petkov Cc: Dave Hansen Cc: Mark Rutland Cc: Alexander Shishkin Cc: Jiri Olsa Cc: Ian Rogers Cc: Adrian Hunter Cc: James Clark Cc: "H. Peter Anvin" --- arch/x86/events/intel/bts.c | 3 --- arch/x86/events/intel/pt.c | 6 ++---- kernel/events/ring_buffer.c | 7 +++---- 3 files changed, 5 insertions(+), 11 deletions(-) diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c index cbac54cb3a9e..5849392cf26d 100644 --- a/arch/x86/events/intel/bts.c +++ b/arch/x86/events/intel/bts.c @@ -66,9 +66,6 @@ static struct pmu bts_pmu; static int buf_nr_pages(struct page *page) { - if (!PagePrivate(page)) - return 1; - return 1 << page_private(page); } diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c index 5754cd405562..49349afee611 100644 --- a/arch/x86/events/intel/pt.c +++ b/arch/x86/events/intel/pt.c @@ -781,8 +781,7 @@ static int topa_insert_pages(struct pt_buffer *buf, int cpu, gfp_t gfp) struct page *p; p = virt_to_page(buf->data_pages[buf->nr_pages]); - if (PagePrivate(p)) - order = page_private(p); + order = page_private(p); if (topa_table_full(topa)) { topa = topa_alloc(cpu, gfp); @@ -1296,8 +1295,7 @@ static int pt_buffer_try_single(struct pt_buffer *buf, int nr_pages) if (!intel_pt_validate_hw_cap(PT_CAP_single_range_output)) goto out; - if (PagePrivate(p)) - order = page_private(p); + order = page_private(p); if (1 << order != nr_pages) goto out; diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 1b1ffe0533e5..9d3d324f5127 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -635,11 +635,10 @@ static struct page *rb_alloc_aux_page(int node, int order) /* * Communicate the allocation size to the driver: * if we managed to secure a high-order allocation, - * set its first page's private to this order; - * !PagePrivate(page) means it's just a normal page. + * set its first page's private to this order, otherwise page's + * private remains zero. */ split_page(page, order); - SetPagePrivate(page); set_page_private(page, order); } @@ -650,7 +649,7 @@ static void rb_free_aux_page(struct perf_buffer *rb, int idx) { struct page *page = virt_to_page(rb->aux_pages[idx]); - ClearPagePrivate(page); + set_page_private(page, 0); __free_page(page); }