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bh=1VGgj1TmnjNrGwceq1Y9mwtgHdomU/ZJ3zMBBp7twvM=; b=3iK6K7ENcx0k/Repn0MSoWvvLTAkiaupoqzbJ2J0EsnnXLCAuzJqYfQQrRP6M7tcWS 1+duRey7zR0EK6d4M6MIZf4HwWIlZNJUmHOrefqK4n3Zz+AsNDIoUJKbehzVNPUnic+f 3GOCMoKT4NWQdH+wrdW5qF5ibSVguw3mP6gbZRUAr5loUpU2Tzq7B0zMguGvtOiEePq8 OtpZKFfu2GGuy0MJloCPFF123Xb80fcWttjRiXSEJPQSPFYoDO7TJj2NwsjhbZdlm5je OPmP9dPsnFRqpYPaVKenngglK5pMLJ+RalIVjr89XF0ICpTBB2d0tw2mjemdF3QrtSYH LITw== X-Gm-Message-State: AO0yUKXLeTr7jBoLd3GntH8blmAjJh47+3B5S/nKd1LE/QKrg0aZutaT NggF7seh9q3XZlgAWmAGbWxu5pS+uiY= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:4e19:be9:c5d0:8483]) (user=surenb job=sendgmr) by 2002:a0d:cb8b:0:b0:50b:1b97:f19a with SMTP id n133-20020a0dcb8b000000b0050b1b97f19amr434148ywd.164.1674848522027; Fri, 27 Jan 2023 11:42:02 -0800 (PST) Date: Fri, 27 Jan 2023 11:40:57 -0800 In-Reply-To: <20230127194110.533103-1-surenb@google.com> Mime-Version: 1.0 References: <20230127194110.533103-1-surenb@google.com> X-Mailer: git-send-email 2.39.1.456.gfc5497dd1b-goog Message-ID: <20230127194110.533103-21-surenb@google.com> Subject: [PATCH v2 20/33] 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, paulmck@kernel.org, mingo@redhat.com, will@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, rppt@kernel.org, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@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?1756206242823622585?= X-GMAIL-MSGID: =?utf-8?q?1756206242823622585?= 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 57cb3a2ac9b1..3baf218836bb 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2399,11 +2399,13 @@ do_vmi_align_munmap(struct vma_iterator *vmi, 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_start_write(next); downgrade = false; - else if (prev && (prev->vm_flags & VM_GROWSUP)) + } else if (prev && (prev->vm_flags & VM_GROWSUP)) { + vma_start_write(prev); downgrade = false; - else + } else mmap_write_downgrade(mm); }