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Wed, 22 Mar 2023 13:09:28 -0700 (PDT) From: Lorenzo Stoakes To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton Cc: David Hildenbrand , Matthew Wilcox , Vlastimil Babka , "Liam R . Howlett" , maple-tree@lists.infradead.org, Vernon Yang , Lorenzo Stoakes Subject: [PATCH v4 2/4] mm/mmap/vma_merge: fold curr, next assignment logic Date: Wed, 22 Mar 2023 20:09:20 +0000 Message-Id: X-Mailer: git-send-email 2.39.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: gx7brjno651oogzhhi6gtp6hcqt9ncnk X-Rspam-User: X-Rspamd-Queue-Id: C3BAE14001F X-Rspamd-Server: rspam06 X-HE-Tag: 1679515771-397011 X-HE-Meta: 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 ILJIcvp7 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000062, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Use find_vma_intersection() and vma_lookup() to both simplify the logic and to fold the end == next->vm_start condition into one block. This groups all of the simple range checks together and establishes the invariant that, if prev, curr or next are non-NULL then their positions are as expected. This has no functional impact. Signed-off-by: Lorenzo Stoakes Reviewed-by: Vlastimil Babka Reviewed-by: Liam R. Howlett --- mm/mmap.c | 24 +++++++++++------------- 1 file changed, 11 insertions(+), 13 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index c9834364ac98..dbdbb92493b2 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -930,15 +930,14 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, if (vm_flags & VM_SPECIAL) return NULL; - curr = find_vma(mm, prev ? prev->vm_end : 0); - if (curr && curr->vm_end == end) /* cases 6, 7, 8 */ - next = find_vma(mm, curr->vm_end); - else - next = curr; + /* Does the input range span an existing VMA? (cases 5 - 8) */ + curr = find_vma_intersection(mm, prev ? prev->vm_end : 0, end); - /* In cases 1 - 4 there's no CCCC vma */ - if (curr && end <= curr->vm_start) - curr = NULL; + if (!curr || /* cases 1 - 4 */ + end == curr->vm_end) /* cases 6 - 8, adjacent VMA */ + next = vma_lookup(mm, end); + else + next = NULL; /* case 5 */ /* verify some invariant that must be enforced by the caller */ VM_WARN_ON(prev && addr <= prev->vm_start); @@ -959,11 +958,10 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, } } /* Can we merge the successor? */ - if (next && end == next->vm_start && - mpol_equal(policy, vma_policy(next)) && - can_vma_merge_before(next, vm_flags, - anon_vma, file, pgoff+pglen, - vm_userfaultfd_ctx, anon_name)) { + if (next && mpol_equal(policy, vma_policy(next)) && + can_vma_merge_before(next, vm_flags, + anon_vma, file, pgoff+pglen, + vm_userfaultfd_ctx, anon_name)) { merge_next = true; } -- 2.39.2