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[90.233.203.182]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-54c1e5c188bsm125274e87.64.2025.04.03.04.17.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Apr 2025 04:17:24 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Thu, 3 Apr 2025 13:17:22 +0200 To: Shakeel Butt Cc: Andrew Morton , Uladzislau Rezki , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: Re: [PATCH] memcg: vmalloc: simplify MEMCG_VMALLOC updates Message-ID: References: <20250403053326.26860-1-shakeel.butt@linux.dev> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250403053326.26860-1-shakeel.butt@linux.dev> On Wed, Apr 02, 2025 at 10:33:26PM -0700, Shakeel Butt wrote: > The vmalloc region can either be charged to a single memcg or none. At > the moment kernel traverses all the pages backing the vmalloc region to > update the MEMCG_VMALLOC stat. However there is no need to look at all > the pages as all those pages will be charged to a single memcg or none. > Simplify the MEMCG_VMALLOC update by just looking at the first page of > the vmalloc region. > > Signed-off-by: Shakeel Butt > --- > mm/vmalloc.c | 13 +++++-------- > 1 file changed, 5 insertions(+), 8 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 3ed720a787ec..cdae76994488 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3370,12 +3370,12 @@ void vfree(const void *addr) > > if (unlikely(vm->flags & VM_FLUSH_RESET_PERMS)) > vm_reset_perms(vm); > + if (vm->nr_pages && !(vm->flags & VM_MAP_PUT_PAGES)) > + mod_memcg_page_state(vm->pages[0], MEMCG_VMALLOC, -vm->nr_pages); > Could you please add a comment stating that the first page should be modified? Yes, the comment is clear, but git blame/log takes time. Reviewed-by: Uladzislau Rezki (Sony) -- Uladzislau Rezki