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Mon, 09 Jan 2023 12:54:31 -0800 (PST) Date: Mon, 9 Jan 2023 12:53:15 -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: <20230109205336.3665937-21-surenb@google.com> Subject: [PATCH 20/41] mm/mmap: write-lock VMAs in vma_adjust 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-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230109_130043_725147_CC143F10 X-CRM114-Status: GOOD ( 16.48 ) 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_adjust modifies a VMA and possibly its neighbors. Write-lock them before making the modifications. Signed-off-by: Suren Baghdasaryan --- mm/mmap.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/mm/mmap.c b/mm/mmap.c index f6ca4a87f9e2..1e2154137631 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -614,6 +614,12 @@ inline int vma_expand(struct ma_state *mas, struct vm_area_struct *vma, * The following helper function should be used when such adjustments * are necessary. The "insert" vma (if any) is to be inserted * before we drop the necessary locks. + * 'expand' vma is always locked before it's passed to __vma_adjust() + * from vma_merge() because vma should not change from the moment + * can_vma_merge_{before|after} decision is made. + * 'insert' vma is used only by __split_vma() and it's always a brand + * new vma which is not yet added into mm's vma tree, therefore no need + * to lock it. */ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert, @@ -633,6 +639,10 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, MA_STATE(mas, &mm->mm_mt, 0, 0); struct vm_area_struct *exporter = NULL, *importer = NULL; + vma_write_lock(vma); + if (next) + vma_write_lock(next); + if (next && !insert) { if (end >= next->vm_end) { /* @@ -676,8 +686,11 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, * If next doesn't have anon_vma, import from vma after * next, if the vma overlaps with it. */ - if (remove_next == 2 && !next->anon_vma) + if (remove_next == 2 && !next->anon_vma) { exporter = next_next; + if (exporter) + vma_write_lock(exporter); + } } else if (end > next->vm_start) { /* @@ -850,6 +863,8 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, if (remove_next == 2) { remove_next = 1; next = next_next; + if (next) + vma_write_lock(next); goto again; } }