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bh=zeEKIs6RouZ3NeHI7ZJ8m5Jmv1yLdTyFBRJo2pt5tCE=; b=FV5sNiMFzNHCNtvK23N/vPhSa88H749KUN2uP8iGhzQx7K+wYFs1fqloQJUvbcXwwg R6OKWNFPaTzj3aQ2TYOncfxBOFMPMgNgy26wQgmT1raRUN6gkZDZsu+ISTS/H0Z67FfD y//3p7Ht8NcQcJOsE0R5EKGDQBbSVAmN5Jp5V/fIvBJFu7WIKaMjqfJeR/XbsZ3ugZ9O Gf7cNJgPhJhHE/ssF9UCDaxtENN77oeH8NbNvBolB80oYXxW+QFw3sgRU+bDxqDmkptv Y19RdCjRxtkZZRhGP3oFjspef3lPMMBzFiMjQ+Cl8BTrRAWDnCYOqQo8/9RKAG8c+PBs lGKA== X-Gm-Message-State: AO0yUKXXbwg/WF7QEdet7cIP1MfWQvGumGsRur2t0XDBnuXUE5A3xB82 /BFlWIVTGqFtpiO7QVMvyvvaD8FvLws= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:f781:d5ed:1806:6ebb]) (user=surenb job=sendgmr) by 2002:a5b:604:0:b0:859:2acc:deb6 with SMTP id d4-20020a5b0604000000b008592accdeb6mr561571ybq.79.1676524725671; Wed, 15 Feb 2023 21:18:45 -0800 (PST) Date: Wed, 15 Feb 2023 21:17:36 -0800 In-Reply-To: <20230216051750.3125598-1-surenb@google.com> Mime-Version: 1.0 References: <20230216051750.3125598-1-surenb@google.com> X-Mailer: git-send-email 2.39.1.581.gbfd45094c4-goog Message-ID: <20230216051750.3125598-22-surenb@google.com> Subject: [PATCH v3 21/35] 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, chriscli@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, michalechner92@googlemail.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, Suren Baghdasaryan 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?1757963748559215981?= X-GMAIL-MSGID: =?utf-8?q?1757963748559215981?= 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 118b2246bba9..00f8c5798936 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); }