From nobody Sat Feb 7 10:44:49 2026 Received: from mail-pf1-f202.google.com (mail-pf1-f202.google.com [209.85.210.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C820E1DF973 for ; Tue, 26 Nov 2024 18:40:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732646443; cv=none; b=bkpw5/Ugv8tSSP/yCRgu1B/oPYGoFSUbnKkLXZ11nlGSizf9+xQkQwh0Ztb1HdS2QFpSzTPXzf6PXU6j8RJMMgcmwEF8By+Oj/l1aEUEFvuuzVk6EMcfn1FRK8MVXe7XutN4B0LdHYPepFhAbVdIs3e56Rg2GZk9lzs6OaM34O0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732646443; c=relaxed/simple; bh=kobwXc6tmkTAygusWJ9qIVEQqqZsRYGXaPpK6AJbvPE=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=NhlkzVi5O4YOJGYyYgmyNqM2pEpXbXbDSH4+gej+xeHrwVMYqRaM3mi+n8u7wFCoE+WgBGySKi00UbeYAoa4PTnhZibW+guHq9EFKuiVD1z33YSccsmLqIk8+rAAe5i/ULW0qZ88qX3d1/IGDpZc/PVBJC9WZbT0BUIPAs7NUKY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--cmllamas.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=R4u6DUF4; arc=none smtp.client-ip=209.85.210.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--cmllamas.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="R4u6DUF4" Received: by mail-pf1-f202.google.com with SMTP id d2e1a72fcca58-72524409ab8so723098b3a.2 for ; Tue, 26 Nov 2024 10:40:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1732646441; x=1733251241; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=sQAKTawIpYzMqOEmfUklmOtYHhl/FZVnlNMqQiUQFZQ=; b=R4u6DUF4HLpW3Hj+WiNMFCIarNlyOUAvvbqI0Y58+mOLaEU7gopPXKw7/oaQ1oUazV +AHso5lswswK9JJbHMt98kXL+rX0PAAeK5G6++KYPkSdCJvjgFMQjMvdkHHF3iUzS3XV uJDlp8DKlNNFKqjpkcAtd2DnN5Da6JrehkIc/KCU746lQxjp7d4mZ5xpJtF9jGnbDABd gIufCf90siY5q2opJsjHlW+a1kOQWIjgdx0OLmCRuZJXkmc84ole1CbGRB0mTJFArID6 TjxmpB8YtaBbil0dqAO7SGO9XI6F2U30qAAdEci13/FFifYN/OuHJoauMqrRLtZaIvdF oqpg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1732646441; x=1733251241; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=sQAKTawIpYzMqOEmfUklmOtYHhl/FZVnlNMqQiUQFZQ=; b=WoIaxK20uwqHetys0kv7sCEuXsUoNsw65+vY90U0NAWCyb4OqAuWhva+M1ULfH53IU scVaI1POgYPFGGW+WY7Pkrs49RGdfYj8iQevpok0ZkFWp0609HYm3R5zODMC75mgz3UW GRs33/3tvyH+hUn04dMGRRKsWXKR30vl8mecE+dv2v8aDAdyNoJtPW+PqQbhpqEXszMu iK+ONLPkNIyQMhP7wfTkwFKjYwp5z6VMfjHleLmBjMVrMUZ+Z87cTKicnb8QDr0hxOmd STY7Wb9Ot+LcjJVYKjC85eBxn9sexWba3MrUeukM4NvIHRw/Imf5VgWinyQKssHahg+8 NbSA== X-Gm-Message-State: AOJu0YzugpiOpCEddZAADDoF4crbD4dIb1gwUzXVWHYRyuUXWdgNDRye rb+83VXdiuQsqgT1baaPMO7Hrjrjdiu03u0fBti6xnH7uXhHZFVUuCE0sL49ka2ZcHqry3fc/Df aRfDjLKSqEg== X-Google-Smtp-Source: AGHT+IGNlsge5O5WMP8QAnHXkYLMBHylGDOARCueNtukNeyuQLPFmoCK0YExqxBDRZmhW8oKC8XQCzwrIJEhmg== X-Received: from pfwz5.prod.google.com ([2002:a05:6a00:1d85:b0:725:22:4960]) (user=cmllamas job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:2e91:b0:71e:795f:92f0 with SMTP id d2e1a72fcca58-7252ff9987fmr309443b3a.3.1732646441070; Tue, 26 Nov 2024 10:40:41 -0800 (PST) Date: Tue, 26 Nov 2024 18:40:10 +0000 In-Reply-To: <20241126184021.45292-1-cmllamas@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241126184021.45292-1-cmllamas@google.com> X-Mailer: git-send-email 2.47.0.338.g60cca15819-goog Message-ID: <20241126184021.45292-8-cmllamas@google.com> Subject: [PATCH v5 7/9] binder: use per-vma lock in page installation From: Carlos Llamas To: Greg Kroah-Hartman , "=?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?=" , Todd Kjos , Martijn Coenen , Joel Fernandes , Christian Brauner , Carlos Llamas , Suren Baghdasaryan Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, Nhat Pham , Johannes Weiner , Barry Song , Hillf Danton , Lorenzo Stoakes Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Use per-vma locking for concurrent page installations, this minimizes contention with unrelated vmas improving performance. The mmap_lock is still acquired when needed though, e.g. before get_user_pages_remote(). Many thanks to Barry Song who posted a similar approach [1]. Link: https://lore.kernel.org/all/20240902225009.34576-1-21cnbao@gmail.com/= [1] Cc: Nhat Pham Cc: Johannes Weiner Cc: Barry Song Cc: Suren Baghdasaryan Cc: Hillf Danton Cc: Lorenzo Stoakes Reviewed-by: Suren Baghdasaryan Signed-off-by: Carlos Llamas --- drivers/android/binder_alloc.c | 67 +++++++++++++++++++++++++--------- 1 file changed, 50 insertions(+), 17 deletions(-) diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c index 71b29bfd8a2e..f550dec4b790 100644 --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -233,6 +233,53 @@ static inline bool binder_alloc_is_mapped(struct binde= r_alloc *alloc) return smp_load_acquire(&alloc->mapped); } =20 +static struct page *binder_page_lookup(struct binder_alloc *alloc, + unsigned long addr) +{ + struct mm_struct *mm =3D alloc->mm; + struct page *page; + long npages =3D 0; + + /* + * Find an existing page in the remote mm. If missing, + * don't attempt to fault-in just propagate an error. + */ + mmap_read_lock(mm); + if (binder_alloc_is_mapped(alloc)) + npages =3D get_user_pages_remote(mm, addr, 1, FOLL_NOFAULT, + &page, NULL); + mmap_read_unlock(mm); + + return npages > 0 ? page : NULL; +} + +static int binder_page_insert(struct binder_alloc *alloc, + unsigned long addr, + struct page *page) +{ + struct mm_struct *mm =3D alloc->mm; + struct vm_area_struct *vma; + int ret =3D -ESRCH; + + /* attempt per-vma lock first */ + vma =3D lock_vma_under_rcu(mm, addr); + if (vma) { + if (binder_alloc_is_mapped(alloc)) + ret =3D vm_insert_page(vma, addr, page); + vma_end_read(vma); + return ret; + } + + /* fall back to mmap_lock */ + mmap_read_lock(mm); + vma =3D vma_lookup(mm, addr); + if (vma && binder_alloc_is_mapped(alloc)) + ret =3D vm_insert_page(vma, addr, page); + mmap_read_unlock(mm); + + return ret; +} + static struct page *binder_page_alloc(struct binder_alloc *alloc, unsigned long index, unsigned long addr) @@ -254,9 +301,7 @@ static int binder_install_single_page(struct binder_all= oc *alloc, unsigned long index, unsigned long addr) { - struct vm_area_struct *vma; struct page *page; - long npages; int ret; =20 if (!mmget_not_zero(alloc->mm)) @@ -268,16 +313,7 @@ static int binder_install_single_page(struct binder_al= loc *alloc, goto out; } =20 - mmap_read_lock(alloc->mm); - vma =3D vma_lookup(alloc->mm, addr); - if (!vma || !binder_alloc_is_mapped(alloc)) { - __free_page(page); - pr_err("%d: %s failed, no vma\n", alloc->pid, __func__); - ret =3D -ESRCH; - goto unlock; - } - - ret =3D vm_insert_page(vma, addr, page); + ret =3D binder_page_insert(alloc, addr, page); switch (ret) { case -EBUSY: /* @@ -287,9 +323,8 @@ static int binder_install_single_page(struct binder_all= oc *alloc, */ ret =3D 0; __free_page(page); - npages =3D get_user_pages_remote(alloc->mm, addr, 1, - FOLL_NOFAULT, &page, NULL); - if (npages <=3D 0) { + page =3D binder_page_lookup(alloc, addr); + if (!page) { pr_err("%d: failed to find page at offset %lx\n", alloc->pid, addr - alloc->vm_start); ret =3D -ESRCH; @@ -307,8 +342,6 @@ static int binder_install_single_page(struct binder_all= oc *alloc, ret =3D -ENOMEM; break; } -unlock: - mmap_read_unlock(alloc->mm); out: mmput_async(alloc->mm); return ret; --=20 2.47.0.338.g60cca15819-goog