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bh=89ITsq4nUiN8d4MMzUNaP/VKvoRvGlIDiLzssAyWMSw=; b=DBTBJvVe3+oAwgyt14LIjDrL4HG9CZIfbWtxhCVftB7Pc2Aiw/JZJAplIhi+NxXJZy +Ovc4HvfTE/ngRHwXNWUoonRLwKarZ3F6aChRAdzpzqaMDXtudugSv74mgtBEt2ls8sE MeuVnQC5H+r2wgwydXTmEtidi4J7AkUeMCQgULXQdBxqQP9z4USQ5g8fdP/7G3jiNXMS ggFOMOQ9Dq1zXw7lSNMxLHcgzM4eTVMNgoO1d+VcDfkypcR2c1K3RGOrrl4dY1Yt1qsb 7a5kB5fAM0vd4SwUq0iQEwcXnBoQI+hOaHiDBR4uh62SqrxmjcfN0beh0LX/D9NBvKBu DVig== X-Gm-Message-State: AFqh2krVtVF/0/dlDb/GmVKGGcNMK2uDqErFld4JVT8dqlKnY1vSF1hL gez0thUQVC3HlhECsE93lInml48WlTY= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:9393:6f7a:d410:55ca]) (user=surenb job=sendgmr) by 2002:a0d:eacb:0:b0:485:126c:3834 with SMTP id t194-20020a0deacb000000b00485126c3834mr6100451ywe.360.1673297684211; Mon, 09 Jan 2023 12:54:44 -0800 (PST) Date: Mon, 9 Jan 2023 12:53:20 -0800 In-Reply-To: <20230109205336.3665937-1-surenb@google.com> Mime-Version: 1.0 References: <20230109205336.3665937-1-surenb@google.com> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20230109205336.3665937-26-surenb@google.com> Subject: [PATCH 25/41] mm/mmap: write-lock adjacent VMAs if they can grow into unmapped area From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, paulmck@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, punit.agrawal@bytedance.com, lstoakes@gmail.com, peterjung1337@gmail.com, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@google.com, hughlynch@google.com, leewalsh@google.com, posk@google.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com, surenb@google.com X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1754580169331441071?= X-GMAIL-MSGID: =?utf-8?q?1754580169331441071?= While unmapping VMAs, adjacent VMAs might be able to grow into the area being unmapped. In such cases write-lock adjacent VMAs to prevent this growth. Signed-off-by: Suren Baghdasaryan --- mm/mmap.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 0d767ce043af..30c7d1c5206e 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2461,11 +2461,13 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma, * down_read(mmap_lock) and collide with the VMA we are about to unmap. */ if (downgrade) { - if (next && (next->vm_flags & VM_GROWSDOWN)) + if (next && (next->vm_flags & VM_GROWSDOWN)) { + vma_write_lock(next); downgrade = false; - else if (prev && (prev->vm_flags & VM_GROWSUP)) + } else if (prev && (prev->vm_flags & VM_GROWSUP)) { + vma_write_lock(prev); downgrade = false; - else + } else mmap_write_downgrade(mm); }