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 986B2C61DA4 for ; Wed, 15 Mar 2023 20:17:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232297AbjCOURc (ORCPT ); Wed, 15 Mar 2023 16:17:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36306 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232468AbjCOUR3 (ORCPT ); Wed, 15 Mar 2023 16:17:29 -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 A36801C589 for ; Wed, 15 Mar 2023 13:17:27 -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 3D42261D90 for ; Wed, 15 Mar 2023 20:17:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B23BC433D2; Wed, 15 Mar 2023 20:17:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1678911446; bh=Wl/nR+WqM/ZnTH1k/+nrPFTOvE4hv3Oqo3VJ1FDDCbQ=; h=Date:To:From:Subject:From; b=M8veGxN0r6vLHilWpl/AKKw+/q7PrCIEormpkqWOkBZHQZThRZo3reFr7VvDTTqo1 BGHgBS71EUmTpGF+S7u0MNroCXDQ16eCTgjZej1oJNydRfaKnvPYT/2Q1M32SIxNHM tTXz8TrK965Ijwny/3FSmRMEDi8gFWMIOPGKnXa0= Date: Wed, 15 Mar 2023 13:17:26 -0700 To: mm-commits@vger.kernel.org, willy@infradead.org, surenb@google.com, lstoakes@gmail.com, Liam.Howlett@oracle.com, vbabka@suse.cz, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-mmap-vma_merge-set-mid-to-null-if-not-applicable.patch added to mm-unstable branch Message-Id: <20230315201726.9B23BC433D2@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/mmap/vma_merge: set mid to NULL if not applicable has been added to the -mm mm-unstable branch. Its filename is mm-mmap-vma_merge-set-mid-to-null-if-not-applicable.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-vma_merge-set-mid-to-null-if-not-applicable.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: Vlastimil Babka Subject: mm/mmap/vma_merge: set mid to NULL if not applicable Date: Thu, 9 Mar 2023 12:12:54 +0100 There are several places where we test if 'mid' is really the area NNNN in the diagram and the tests have two variants and are non-obvious to follow. Instead, set 'mid' to NULL up-front if it's not the NNNN area, and simplify the tests. Also update the description in comment accordingly. Link: https://lkml.kernel.org/r/20230309111258.24079-7-vbabka@suse.cz Signed-off-by: Vlastimil Babka Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Matthew Wilcox (Oracle) Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton --- mm/mmap.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) --- a/mm/mmap.c~mm-mmap-vma_merge-set-mid-to-null-if-not-applicable +++ a/mm/mmap.c @@ -861,10 +861,11 @@ can_vma_merge_after(struct vm_area_struc * * The following mprotect cases have to be considered, where AAAA is * the area passed down from mprotect_fixup, never extending beyond one - * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: + * vma, PPPPPP is the prev vma specified, NNNN is a vma that overlaps + * the area AAAA and XXXXXX the next vma after AAAA: * * AAAA AAAA AAAA - * PPPPPPNNNNNN PPPPPPXXXXXX PPPPPPNNNNNN + * PPPPPPXXXXXX PPPPPPXXXXXX PPPPPPNNNNNN * cannot merge might become might become * PPXXXXXXXXXX PPPPPPPPPPNN * mmap, brk or case 4 below case 5 below @@ -892,9 +893,10 @@ can_vma_merge_after(struct vm_area_struc * * In the code below: * PPPP is represented by *prev - * NNNN is represented by *mid (and possibly equal to *next) - * XXXX is represented by *next or not represented at all. - * AAAA is not represented - it will be merged or the function will return NULL + * NNNN is represented by *mid or not represented at all (NULL) + * XXXX is represented by *next or not represented at all (NULL) + * AAAA is not represented - it will be merged and the vma containing the + * area is returned, or the function will return NULL */ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, struct vm_area_struct *prev, unsigned long addr, @@ -931,6 +933,9 @@ struct vm_area_struct *vma_merge(struct else next = mid; + if (mid && end <= mid->vm_start) + mid = NULL; + /* verify some invariant that must be enforced by the caller */ VM_WARN_ON(prev && addr <= prev->vm_start); VM_WARN_ON(mid && end > mid->vm_end); @@ -965,7 +970,7 @@ struct vm_area_struct *vma_merge(struct remove = next; /* case 1 */ vma_end = next->vm_end; err = dup_anon_vma(prev, next); - if (mid != next) { /* case 6 */ + if (mid) { /* case 6 */ remove = mid; remove2 = next; if (!next->anon_vma) @@ -973,7 +978,7 @@ struct vm_area_struct *vma_merge(struct } } else if (merge_prev) { err = 0; /* case 2 */ - if (mid && end > mid->vm_start) { + if (mid) { err = dup_anon_vma(prev, mid); if (end == mid->vm_end) { /* case 7 */ remove = mid; @@ -995,7 +1000,7 @@ struct vm_area_struct *vma_merge(struct vma_end = next->vm_end; vma_pgoff = next->vm_pgoff; err = 0; - if (mid != next) { /* case 8 */ + if (mid) { /* case 8 */ vma_pgoff = mid->vm_pgoff; remove = mid; err = dup_anon_vma(next, mid); _ Patches currently in -mm which might be from vbabka@suse.cz are mm-page_alloc-reduce-page-alloc-free-sanity-checks.patch mm-mmap-vma_merge-use-only-primary-pointers-for-preparing-merge.patch mm-mmap-vma_merge-use-the-proper-vma-pointer-in-case-3.patch mm-mmap-vma_merge-use-the-proper-vma-pointers-in-cases-1-and-6.patch mm-mmap-vma_merge-use-the-proper-vma-pointer-in-case-4.patch mm-mmap-vma_merge-initialize-mid-and-next-in-natural-order.patch mm-mmap-vma_merge-set-mid-to-null-if-not-applicable.patch mm-mmap-vma_merge-rename-adj_next-to-adj_start.patch mm-mmap-vma_merge-convert-mergeability-checks-to-return-bool.patch mm-mmap-start-distinguishing-if-vma-can-be-removed-in-mergeability-test.patch mm-mremap-simplify-vma-expansion-again.patch