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Wed, 28 Jan 2026 14:57:25 -0800 (PST) Received: from greenjustin3.nyc.corp.google.com ([2a00:79e0:2c11:9:6215:4385:468c:4289]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-894d375b62asm27815526d6.41.2026.01.28.14.57.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Jan 2026 14:57:24 -0800 (PST) From: Justin Green To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, david@kernel.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-kernel@vger.kernel.org, greenjustin@chromium.org, greenjustin@google.com, rientjes@google.com, bgeffon@google.com, arjunroy@google.com Subject: [PATCH] mm: Refactor vma_map_pages to use vm_insert_pages Date: Wed, 28 Jan 2026 17:56:47 -0500 Message-ID: <20260128225648.2938636-1-greenjustin@chromium.org> X-Mailer: git-send-email 2.53.0.rc1.217.geba53bf80e-goog Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" vma_map_pages currently calls vm_insert_page on each individual page in the mapping, which creates significant overhead because we are repeatedly spinlocking. Instead, we should batch insert pages using vm_insert_pages, which amortizes the cost of the spinlock. Tested through watching hardware accelerated video on a MTK ChromeOS device. This particular path maps both a V4L2 buffer and a GEM allocated buffer into userspace and converts the contents from one pixel format to another. Both vb2_mmap() and mtk_gem_object_mmap() exercise this pathway. Signed-off-by: Justin Green Acked-by: Brian Geffon Reviewed-by: Arjun Roy Reviewed-by: Matthew Wilcox (Oracle) --- mm/memory.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index da360a6eb8a4..7ae6ac42e7d8 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2499,7 +2499,6 @@ static int __vm_map_pages(struct vm_area_struct *vma,= struct page **pages, { unsigned long count =3D vma_pages(vma); unsigned long uaddr =3D vma->vm_start; - int ret, i; =20 /* Fail if the user requested offset is beyond the end of the object */ if (offset >=3D num) @@ -2509,14 +2508,7 @@ static int __vm_map_pages(struct vm_area_struct *vma= , struct page **pages, if (count > num - offset) return -ENXIO; =20 - for (i =3D 0; i < count; i++) { - ret =3D vm_insert_page(vma, uaddr, pages[offset + i]); - if (ret < 0) - return ret; - uaddr +=3D PAGE_SIZE; - } - - return 0; + return vm_insert_pages(vma, uaddr, pages + offset, &count); } =20 /** --=20 2.53.0.rc1.217.geba53bf80e-goog