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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-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: E16C9C0004 X-Stat-Signature: dgf5tjoxu4o3gguc71jhqgfgpbqarrk7 X-HE-Tag: 1674848522-298337 X-HE-Meta: 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 bQ+w5nzq T89oUv2+JZ/2sy+R0RwG+SCDtdDUmWSC6xcK5wodWihCkQl5CIi600MZTwHkaN85yrN/pFLFgDfdlkNQi18PdH1koOY1qTgmgyx/aT+GAQUl/DMktW0msOOoOh5BqpNAhyngwlxbxDVcQHEhbZYiBLqwh1elCfRIjLg6AN4weihqKApsc+d7McwXfDI4MCvzgOFohnI50XvEa3Umf7KDTVN3Llap4Bwu2oDV4m0k+DYAGDJu4WsUEFD0Qxtj9N10VoBd+v6xB94OBCtDcYQXIeIdiTPmRH85uSq0qyhBGFuJPyOMqmlQRDcBjmijKEAgJohOEwm/TF4S0JeCS52fOOBYZ7fF1C5BXYZ23tgbvk5A9DGOCRTYd7NDAiBM1MGuValG5K3CoG8E9KTJWdBtkfpbIeBgv7YYVlfdPY27EWPpP+PzjPPmgJSnRVNJorIVPksTH4709avZ0m9MRhPmOx26lvlmDtRSFOOgboav0aGMtfPCQ2bMngJgWhmh9TQm94FQFm3+7RYeu1jG28TR/w7mP4QxHaNF/iQGcQQXBHE7tn3JdL1f/VmcFBfVinorIUelqh6BICXNZXWS/mkUtwdZ48Vk0iyft9MZ0JlfDleYdtt/c1edXhpxxUg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.011723, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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); }