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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1785594758; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9ri60wTe3lRq/wyazLvLAJHMWphJ53DXAVPzpa92v8E=; b=b1MJ2KvVydMkbGpiSM2vSJhXzcu6GCUhE0pgi57LctVN7QP7thbs+314VxzqPZ0y2fArlf zLY1i65Y6JE/Xt/8+PFW0EPl2ofxtl+fUxbw+hmqUM1Nk0YFt8YDyt37ciBE3FfwWAblHr Ops92EnsY7B5tMRb4P3SdCuy3WE/xkA= From: Usama Arif To: Zi Yan Cc: Usama Arif , David Hildenbrand , "Matthew Wilcox (Oracle)" , Andrew Morton , Muchun Song , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Gregory Price , Ying Huang , Alistair Popple , Johannes Weiner , Qi Zheng , Shakeel Butt , Kairui Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Thomas Gleixner , Borislav Petkov , Dave Hansen , x86@kernel.org, Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , "H. Peter Anvin" , linux-perf-users@vger.kernel.org Subject: Re: [PATCH RFC 02/14] perf/ring_buffer: stop using PG_private as AUX page high-order marker Date: Sat, 1 Aug 2026 07:32:26 -0700 Message-ID: <20260801143227.1267657-1-usama.arif@linux.dev> In-Reply-To: <20260731-remove-pg_private-v1-2-142c97ba3562@nvidia.com> References: Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On Fri, 31 Jul 2026 22:13:25 -0400 Zi Yan wrote: > 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 ring buffer and its users. > nit: only "in the" ring buffer? > It prepares for a future commit that remove PG_private. > > No functional change intended. > > Assisted-by: Claude:claude-opus-4-8 > Assisted-by: Codex:gpt-5 > Signed-off-by: Zi Yan > To: Peter Zijlstra > To: Ingo Molnar > To: Arnaldo Carvalho de Melo > To: Namhyung Kim > To: Thomas Gleixner > To: Borislav Petkov > To: Dave Hansen > To: x86@kernel.org > Cc: Mark Rutland > Cc: Alexander Shishkin > Cc: Jiri Olsa > Cc: Ian Rogers > Cc: Adrian Hunter > Cc: James Clark > Cc: "H. Peter Anvin" > Cc: linux-perf-users@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > --- > 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 cbac54cb3a9ec..5849392cf26d5 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; > - For order 0, 1 << 0 is 1, which is exactly what the !PagePrivate(page) so LGTM. The commit message probably needs more text but everything else looks good. Feel free to add Acked-by: Usama Arif > return 1 << page_private(page); > } > > diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c > index b5726b50e77db..29d8b4a3560cd 100644 > --- a/arch/x86/events/intel/pt.c > +++ b/arch/x86/events/intel/pt.c > @@ -774,8 +774,7 @@ 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); > @@ -1289,8 +1288,7 @@ 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 9fe92161715e0..061b5cb222266 100644 > --- a/kernel/events/ring_buffer.c > +++ b/kernel/events/ring_buffer.c > @@ -630,11 +630,10 @@ 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); > } > > @@ -645,7 +644,7 @@ 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); > } > > > -- > 2.53.0 > >