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 54984C00140 for ; Sun, 21 Aug 2022 23:42:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231679AbiHUXmJ (ORCPT ); Sun, 21 Aug 2022 19:42:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41884 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230056AbiHUXmI (ORCPT ); Sun, 21 Aug 2022 19:42:08 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65DD0167D0 for ; Sun, 21 Aug 2022 16:42:07 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 1606CB80E6C for ; Sun, 21 Aug 2022 23:42:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ACC45C433D7; Sun, 21 Aug 2022 23:42:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1661125324; bh=7g5pcIc9fs5VC0YyypTA/PKZnRRRPxyPJRsiBXc4F2o=; h=Date:To:From:Subject:From; b=Y7TP5FQi+Auc6SiroND69jsSCLe2ggfB0m0fIQM6oPUH+GIFavg/wqjwcPibQTeMy Ia15n3kfXqzkJr+GLPFpcNxF3SzY+KeYb/ov8aU9nlldZUwuJDd1mXNxd3ci/NqLJb +/EzLdUkzzUmuD3N4nEDMfat10jbV9jE7dnU2kTc= Date: Sun, 21 Aug 2022 16:42:03 -0700 To: mm-commits@vger.kernel.org, willy@infradead.org, tytso@mit.edu, songmuchun@bytedance.com, slava@dubeyko.com, roman.gushchin@linux.dev, martin.petersen@oracle.com, keescook@chromium.org, kch@nvidia.com, jlayton@kernel.org, ira.weiny@intel.com, damien.lemoal@opensource.wdc.com, brauner@kernel.org, axboe@kernel.dk, arnd@arndb.de, fmdefrancesco@gmail.com, akpm@linux-foundation.org From: Andrew Morton Subject: + hfs-unmap-the-page-in-the-fail_page-label.patch added to mm-nonmm-unstable branch Message-Id: <20220821234204.ACC45C433D7@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: hfs: unmap the page in the "fail_page" label has been added to the -mm mm-nonmm-unstable branch. Its filename is hfs-unmap-the-page-in-the-fail_page-label.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/hfs-unmap-the-page-in-the-fail_page-label.patch This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: "Fabio M. De Francesco" Subject: hfs: unmap the page in the "fail_page" label Date: Sun, 21 Aug 2022 20:03:58 +0200 Patch series "hfs: Replace kmap() with kmap_local_page()". kmap() is being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmaps pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and still valid. Since its use in fs/hfs is safe everywhere, it should be preferred. Therefore, replace kmap() with kmap_local_page() in fs/hfs. Where possible, use the suited standard helpers (memzero_page(), memcpy_page()) instead of open coding kmap_local_page() plus memset() or memcpy(). Fix a bug due to a page being not unmapped if the code jumps to the "fail_page" label (1/3). Tested in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. This patch (of 3): Several paths within hfs_btree_open() jump to the "fail_page" label where put_page() is called while the page is still mapped. Call kunmap() to unmap the page soon before put_page(). Link: https://lkml.kernel.org/r/20220821180400.8198-1-fmdefrancesco@gmail.com Link: https://lkml.kernel.org/r/20220821180400.8198-2-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco Reviewed-by: Ira Weiny Reviewed-by: Viacheslav Dubeyko Cc: Arnd Bergmann Cc: Chaitanya Kulkarni Cc: Christian Brauner (Microsoft) Cc: Damien Le Moal Cc: Matthew Wilcox ] Cc: Jeff Layton Cc: Jens Axboe Cc: Kees Cook Cc: Martin K. Petersen Cc: Muchun Song Cc: Roman Gushchin Cc: Theodore Ts'o Signed-off-by: Andrew Morton --- fs/hfs/btree.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/hfs/btree.c~hfs-unmap-the-page-in-the-fail_page-label +++ a/fs/hfs/btree.c @@ -124,6 +124,7 @@ struct hfs_btree *hfs_btree_open(struct return tree; fail_page: + kunmap(page); put_page(page); free_inode: tree->inode->i_mapping->a_ops = &hfs_aops; _ Patches currently in -mm which might be from fmdefrancesco@gmail.com are hfsplus-unmap-the-page-in-the-fail_page-label.patch hfsplus-convert-kmap-to-kmap_local_page-in-bnodec.patch hfsplus-convert-kmap-to-kmap_local_page-in-bitmapc.patch hfsplus-convert-kmap-to-kmap_local_page-in-btreec.patch fs-isofs-replace-kmap-with-kmap_local_page.patch kexec-replace-kmap-with-kmap_local_page.patch hfs-unmap-the-page-in-the-fail_page-label.patch hfs-replace-kmap-with-kmap_local_page-in-bnodec.patch hfs-replace-kmap-with-kmap_local_page-in-btreec.patch