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Fri, 27 Jan 2023 11:41:52 -0800 (PST) Date: Fri, 27 Jan 2023 11:40:53 -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: <20230127194110.533103-17-surenb@google.com> Subject: [PATCH v2 16/33] mm/mmap: write-lock VMA before shrinking or expanding it 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-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230127_114155_770163_3AB0337A X-CRM114-Status: UNSURE ( 9.79 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org vma_expand and vma_shrink change VMA boundaries. Expansion might also result in freeing of an adjacent VMA. Write-lock affected VMAs to prevent concurrent page faults. Signed-off-by: Suren Baghdasaryan --- mm/mmap.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/mmap.c b/mm/mmap.c index 6fff76334177..60038c24d836 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -674,6 +674,9 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, ret = dup_anon_vma(vma, next); if (ret) return ret; + + /* Lock the VMA before removing it */ + vma_start_write(next); } init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL); @@ -686,6 +689,7 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, if (vma_iter_prealloc(vmi)) goto nomem; + vma_start_write(vma); vma_adjust_trans_huge(vma, start, end, 0); /* VMA iterator points to previous, so set to start if necessary */ if (vma_iter_addr(vmi) != start) @@ -725,6 +729,7 @@ int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma, if (vma_iter_prealloc(vmi)) return -ENOMEM; + vma_start_write(vma); init_vma_prep(&vp, vma); vma_adjust_trans_huge(vma, start, end, 0); vma_prepare(&vp);