From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14760C19F2C for ; Mon, 1 Aug 2022 18:48:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233578AbiHASsI (ORCPT ); Mon, 1 Aug 2022 14:48:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233464AbiHASsG (ORCPT ); Mon, 1 Aug 2022 14:48:06 -0400 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F06925293 for ; Mon, 1 Aug 2022 11:48:04 -0700 (PDT) Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 271EmXJ1003686 for ; Mon, 1 Aug 2022 11:48:04 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=facebook; bh=/0Ba2BW84txtNVUrI6XJ5P58G9O2nZCOBVVyrrbvLJM=; b=KjsEEFCrhCrTXrG2s0W8PGbKnOpceSsX7WI/vOk/ONLAPON5BgOg+ChsFMTxAiKuFBIH +2SuGM5RtRZV/XzxDolQ87kK5z3WJ4rV27kMh0YMSxx8V08hZziQdHJEFWyQbA/fQFDb xPsWHQG3NsKs4ysJvyPei2wzwIIBZgG2JXk= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3hmyymx2ea-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 01 Aug 2022 11:48:04 -0700 Received: from twshared5413.23.frc3.facebook.com (2620:10d:c085:108::4) by mail.thefacebook.com (2620:10d:c085:11d::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Mon, 1 Aug 2022 11:48:03 -0700 Received: by devvm6390.atn0.facebook.com (Postfix, from userid 352741) id D2E391AAF666; Mon, 1 Aug 2022 11:47:55 -0700 (PDT) From: To: , , , , , , CC: alexlzhu Subject: [PATCH v2] mm: fix alginment of VMA for memory mapped files on THP Date: Mon, 1 Aug 2022 11:47:40 -0700 Message-ID: <20220801184740.2134364-1-alexlzhu@fb.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-GUID: ut0jxSWvzKW4Gk1hAjJsF4Z5JKogbogF X-Proofpoint-ORIG-GUID: ut0jxSWvzKW4Gk1hAjJsF4Z5JKogbogF X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-08-01_08,2022-08-01_01,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: alexlzhu With CONFIG_READ_ONLY_THP_FOR_FS, the Linux kernel supports using THPs fo= r read-only mmapped files, such as shared libraries. However, the kernel makes no attempt to actually align those mappings on 2MB boundarie= s, which makes it impossible to use those THPs most of the time. This issue applies to general file mapping THP as well as existing setups using CONFIG_READ_ONLY_THP_FOR_FS. This is easily fixed by using thp_get_unmapped_area for the unmapped_area function in btrfs, which is what ext2, ext4, fuse, and xfs all use. The problem can be seen in /proc/PID/smaps where THPeligible is set to 0 on mappings to eligible shared object files as shown below. Before this patch: 7fc6a7e18000-7fc6a80cc000 r-xp 00000000 00:1e 199856 /usr/lib64/libcrypto.so.1.1.1k Size: 2768 kB THPeligible: 0 VmFlags: rd ex mr mw me With this patch the library is mapped at a 2MB aligned address: fbdfe200000-7fbdfe4b4000 r-xp 00000000 00:1e 199856 /usr/lib64/libcrypto.so.1.1.1k Size: 2768 kB THPeligible: 1 VmFlags: rd ex mr mw me This fixes the alignment of VMAs for any mmap of a file that has the rd and ex permissions and size >=3D 2MB. The VMA alignment and THPeligible field for anonymous memory is handled separately and is thus not effected by this change. Signed-off-by: alexlzhu --- fs/btrfs/file.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 9dfde1af8a64..2423040db167 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -3808,6 +3808,7 @@ const struct file_operations btrfs_file_operations = =3D { .mmap =3D btrfs_file_mmap, .open =3D btrfs_file_open, .release =3D btrfs_release_file, + .get_unmapped_area =3D thp_get_unmapped_area, .fsync =3D btrfs_sync_file, .fallocate =3D btrfs_fallocate, .unlocked_ioctl =3D btrfs_ioctl, --=20 2.30.2