From nobody Thu Dec 18 05:23:36 2025 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 D6F2C1BDAA0 for ; Tue, 10 Dec 2024 14:31:48 +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=1733841110; cv=none; b=p5Ykn0YZyqHxmi32AskZZcg9PO9z1Jqf1JziFQxDkRWBbafSp9z1SRgy2uj4ABixcuzpz/wq9e7/6mQ/rXSkPt2PH8A62ecWkhHxf4WYBMxRxzBLM7qJMeKcsgHB4QuBN/G0I7xkujV5l2OfDm99pAbUabRJzdCh86XlQmYEsUs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733841110; c=relaxed/simple; bh=rO1N2rkVYmws1D0z0gpSDLKI0Y6nPBUE524EjEd+Y5w=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=hx0f9UIN9+r00EpU9Zxryg4f+T0RKroNH/rn5vFwywtF5Br4icN2BAquYbEsJw3dDXi3zGWWuOc+XxuFLzEpEdmDlIl1Uj+ogbzP5pbxaSSCAwOMZWkbeNRRCPo1D4vc2lx0sOch5ziUcgSXSW/ia1FVbhewRpzG0TOV0odfFg0= 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=cU+xtOn3; 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="cU+xtOn3" Received: by mail-pf1-f202.google.com with SMTP id d2e1a72fcca58-7273a901821so1239401b3a.2 for ; Tue, 10 Dec 2024 06:31:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1733841108; x=1734445908; 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=v9iHcIMEhyrv4IhgIRMWwr7V9q9LzPr5KpOSI5lhdso=; b=cU+xtOn33DsOMiEP+PHSBunCkxrB5MQTtqbDt2HpJA0fo99bay0HmVTHN2Y4CfrKDU zMpPqwdhtcVo1SXIkehXyRr0An6UyCpnDdu6Ptyz+INVOGzEO/oFcwRWT9xrMajkGNLT 7aVat1j522LH+aODP9evN53nIxsy1KwdfuNSaIn2yTtfpeAxTReR7WpIb1J0SWgIrFmx zqEoPRP8cs80nsxhdUHELr2rUNAFVFZXeEMgfaCbRNvhjTBCiiKijJxdYMfU5NIAAFIn VmqRgJRWy+GTL5gEPnYRFBkrPfLUeJpHqxkznhjn7gP7cf61dmhQJpTdBr4zdkXXuQIu 39nA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1733841108; x=1734445908; 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=v9iHcIMEhyrv4IhgIRMWwr7V9q9LzPr5KpOSI5lhdso=; b=peGYDIFAuaNqQYBwnRzcSTJDa3VALo6AOAXpVMkEVItFDgf+RCQWuKaX2TNSokxY1r 0/Xkc4mgOZPdHvPoS+v5nurEJ5x1Zhde/YZ7w0OSK40qaZk3wnHecINqgIRjRSorLwtR g3ruIJnvgYEC6gaoFtjKT5Fa728PkoUjtvHCxKlGFdXJsrzgvR9SGf20/+1Xe9aW10pk uWEpdPOMaun1kO0jV6+sTADnHhcRMwEqoDp1Dk8LbLtaIjPwimChuv0Z970UrAhG3D2t MUCfVNTZltzMNfHOtAQBpBK1uZ4g1FbTdF+CykV+pebDv1lpGw27q5VDLFc6FvtCCH++ N8cw== X-Gm-Message-State: AOJu0Yxj5154bR+AporA5JVhkCClBhqd90Ds0fRkMlU/HtWxJu8uWzL6 jVZ3ELHkyM6VhSx1Hw/w+PlWayQktW62Y0LStsxmwjnmn/Xqo7QSw31Dou7EYzS4tVwTGW1LXLa vsjm7PPH4Fg== X-Google-Smtp-Source: AGHT+IGBybGYX7qQAcCrdzEFZ2ItREUhqifbG4xR18XyvsIuH7ifP5Cg3Z19KNpxgcTxCUdusooUb37r14zc2A== X-Received: from pfbbu3.prod.google.com ([2002:a05:6a00:4103:b0:725:e60b:1e4f]) (user=cmllamas job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:ae16:b0:725:db34:6a7d with SMTP id d2e1a72fcca58-725db346d85mr16204674b3a.23.1733841108144; Tue, 10 Dec 2024 06:31:48 -0800 (PST) Date: Tue, 10 Dec 2024 14:31:03 +0000 In-Reply-To: <20241210143114.661252-1-cmllamas@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241210143114.661252-1-cmllamas@google.com> X-Mailer: git-send-email 2.47.0.338.g60cca15819-goog Message-ID: <20241210143114.661252-8-cmllamas@google.com> Subject: [PATCH v7 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 9cb47e1bc6be..f86bd6ded4f4 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) { @@ -268,9 +315,7 @@ 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)) @@ -282,16 +327,7 @@ 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)) { - binder_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: /* @@ -301,9 +337,8 @@ static int binder_install_single_page(struct binder_all= oc *alloc, */ ret =3D 0; binder_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; @@ -321,8 +356,6 @@ 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