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Howlett" , Matthew Wilcox , linux-mm@kvack.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, maple-tree@lists.infradead.org, Vlastimil Babka Subject: [PATCH 02/10] mm/mmap/vma_merge: use the proper vma pointer in case 3 Date: Thu, 9 Mar 2023 12:12:50 +0100 Message-Id: <20230309111258.24079-3-vbabka@suse.cz> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230309111258.24079-1-vbabka@suse.cz> References: <20230309111258.24079-1-vbabka@suse.cz> MIME-Version: 1.0 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 7E2BB1A0003 X-Stat-Signature: dhgy7n6ogkjafwyfeufeiy464xot69ut X-Rspam-User: X-HE-Tag: 1678360392-900868 X-HE-Meta: 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 MI/3+Qfo eAZWq7vy1IXPy2u8Hl1xAZLNzRX6T2vcd9nlGPgPr0BkRM4+IcxU2qMtPC3f2FjXuWvLbqmIvG21AbNyWBBPUz0osD9fxPUk5YLP/LwNjUep2JOReX2YQqtYZnesGByQsIeDT8nCysTZJJ8kG3CPuioVpW9Nxi8zql1K6SpYLFr94vFAXV+/6eUAv8e0lMXu0cMnA2Bp4xRlYOiDVQ56vQ+L0BY0juDI8IYAKrtS+H/g4JeKlDBqGiriVGg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In case 3 we we use 'next' for everything but vma_pgoff. So use 'next' for that as well, instead of 'mid', for consistency. Then in case 8 we have to use 'mid' explicitly, which should also make the intent more obvious. Adjust the diagram for cases 1-3 in the comment to match the code - we are using 'next' for case 3 so mark the range with XXXX instead of NNNN. For case 2 that's a no-op as the code doesn't touch 'next' or 'mid'. For case 1 it's now wrong but that will be fixed next. No functional change. Signed-off-by: Vlastimil Babka Reviewed-by: Lorenzo Stoakes --- mm/mmap.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 0a8b052e3022..1af4c9bc2c87 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -857,11 +857,11 @@ can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, * mmap, brk or case 4 below case 5 below * mremap move: * AAAA AAAA - * PPPP NNNN PPPPNNNNXXXX + * PPPP XXXX PPPPNNNNXXXX * might become might become * PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or - * PPPPPPPPNNNN 2 or PPPPPPPPXXXX 7 or - * PPPPNNNNNNNN 3 PPPPXXXXXXXX 8 + * PPPPPPPPXXXX 2 or PPPPPPPPXXXX 7 or + * PPPPXXXXXXXX 3 PPPPXXXXXXXX 8 * * It is important for case 8 that the vma NNNN overlapping the * region AAAA is never going to extended over XXXX. Instead XXXX must @@ -978,9 +978,10 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, vma = next; /* case 3 */ vma_start = addr; vma_end = next->vm_end; - vma_pgoff = mid->vm_pgoff; + vma_pgoff = next->vm_pgoff; err = 0; if (mid != next) { /* case 8 */ + vma_pgoff = mid->vm_pgoff; remove = mid; err = dup_anon_vma(next, mid); }