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 630F9C76196 for ; Tue, 11 Apr 2023 21:03:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229504AbjDKVDx (ORCPT ); Tue, 11 Apr 2023 17:03:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59546 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229506AbjDKVDp (ORCPT ); Tue, 11 Apr 2023 17:03:45 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 823D03594 for ; Tue, 11 Apr 2023 14:03:44 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 1EE5860FA0 for ; Tue, 11 Apr 2023 21:03:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 78A2BC433EF; Tue, 11 Apr 2023 21:03:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1681247023; bh=JythWbGSM/S7V//F404rQGUCqx/QlK3QCdZtKrs+xeY=; h=Date:To:From:Subject:From; b=TKerPKIHaVyMFNddyV56Jdp2RCIKIf8ICyUBQF5DsBUW5yPxnzlurfxvSX3SNwgln /v4sTMNjEpees5z2Yu2oL1jsBCFc/bVmShTtr3K4MmObJof7r6R9btQfRsNzcMWSqu pgJE5GWsz7u6ZVu8WxEa97QGRQaLA2gvbWTYKfj0= Date: Tue, 11 Apr 2023 14:03:42 -0700 To: mm-commits@vger.kernel.org, yuzhao@google.com, shuah@kernel.org, sam@ravnborg.org, peterx@redhat.com, hughd@google.com, davem@davemloft.net, anshuman.khandual@arm.com, david@redhat.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-huge_memory-conditionally-call-maybe_mkwrite-and-drop-pte_wrprotect-in-__split_huge_pmd_locked.patch added to mm-unstable branch Message-Id: <20230411210343.78A2BC433EF@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: mm/huge_memory: conditionally call maybe_mkwrite() and drop pte_wrprotect() in __split_huge_pmd_locked() has been added to the -mm mm-unstable branch. Its filename is mm-huge_memory-conditionally-call-maybe_mkwrite-and-drop-pte_wrprotect-in-__split_huge_pmd_locked.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-huge_memory-conditionally-call-maybe_mkwrite-and-drop-pte_wrprotect-in-__split_huge_pmd_locked.patch This patch will later appear in the mm-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: David Hildenbrand Subject: mm/huge_memory: conditionally call maybe_mkwrite() and drop pte_wrprotect() in __split_huge_pmd_locked() Date: Tue, 11 Apr 2023 16:25:12 +0200 No need to call maybe_mkwrite() to then wrprotect if the source PMD was not writable. It's worth nothing that this now allows for PTEs to be writable even if the source PMD was not writable: if vma->vm_page_prot includes write permissions. As documented in commit 931298e103c2 ("mm/userfaultfd: rely on vma->vm_page_prot in uffd_wp_range()"), any mechanism that intends to have pages wrprotected (COW, writenotify, mprotect, uffd-wp, softdirty, ...) has to properly adjust vma->vm_page_prot upfront, to not include write permissions. If vma->vm_page_prot includes write permissions, the PTE/PMD can be writable as default. This now mimics the handling in mm/migrate.c:remove_migration_pte() and in mm/huge_memory.c:remove_migration_pmd(), which has been in place for a long time (except that 96a9c287e25d ("mm/migrate: fix wrongly apply write bit after mkdirty on sparc64") temporarily changed it). Link: https://lkml.kernel.org/r/20230411142512.438404-7-david@redhat.com Signed-off-by: David Hildenbrand Cc: Anshuman Khandual Cc: David S. Miller Cc: Hugh Dickins Cc: Peter Xu Cc: Sam Ravnborg Cc: Shuah Khan Cc: Yu Zhao Signed-off-by: Andrew Morton --- mm/huge_memory.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/mm/huge_memory.c~mm-huge_memory-conditionally-call-maybe_mkwrite-and-drop-pte_wrprotect-in-__split_huge_pmd_locked +++ a/mm/huge_memory.c @@ -2233,11 +2233,10 @@ static void __split_huge_pmd_locked(stru entry = pte_swp_mkuffd_wp(entry); } else { entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); - entry = maybe_mkwrite(entry, vma); + if (write) + entry = maybe_mkwrite(entry, vma); if (anon_exclusive) SetPageAnonExclusive(page + i); - if (!write) - entry = pte_wrprotect(entry); if (!young) entry = pte_mkold(entry); /* NOTE: this may set soft-dirty too on some archs */ _ Patches currently in -mm which might be from david@redhat.com are mm-userfaultfd-fix-uffd-wp-handling-for-thp-migration-entries.patch m68k-mm-use-correct-bit-number-in-_page_swp_exclusive-comment.patch mm-userfaultfd-dont-consider-uffd-wp-bit-of-writable-migration-entries.patch selftests-mm-reuse-read_pmd_pagesize-in-cow-selftest.patch selftests-mm-mkdirty-test-behavior-of-ptepmd_mkdirty-on-vmas-without-write-permissions.patch sparc-mm-dont-unconditionally-set-hw-writable-bit-when-setting-pte-dirty-on-64bit.patch mm-migrate-revert-mm-migrate-fix-wrongly-apply-write-bit-after-mkdirty-on-sparc64.patch mm-huge_memory-revert-partly-revert-mm-thp-carry-over-dirty-bit-when-thp-splits-on-pmd.patch mm-huge_memory-conditionally-call-maybe_mkwrite-and-drop-pte_wrprotect-in-__split_huge_pmd_locked.patch