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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qJJqr-00G1Q8-HB; Tue, 11 Jul 2023 20:20:49 +0000 From: "Matthew Wilcox (Oracle)" To: linux-mm@kvack.org Cc: "Matthew Wilcox (Oracle)" , Arjun Roy , Eric Dumazet , Suren Baghdasaryan , linux-fsdevel@vger.kernel.org, Punit Agrawal Subject: [PATCH v2 2/9] mm: Allow per-VMA locks on file-backed VMAs Date: Tue, 11 Jul 2023 21:20:40 +0100 Message-Id: <20230711202047.3818697-3-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20230711202047.3818697-1-willy@infradead.org> References: <20230711202047.3818697-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 303EF1A0016 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: xihkupwfigz7prtbd5gpg57bn6apdsh4 X-HE-Tag: 1689106864-167981 X-HE-Meta: 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 eVuIRJwy /4w8PJxFxjYpHDI/p2d0wSbR/99PaStsEcMIz2V1kHdn+EluRI6Lz1l40cPMBgI9SzysRXepMN8TPnOTezGGn3U0ZuH9G+R1j8DqT9iB68xU+2qIV5vHHKdG28BaVhtFP9FhXCnXMpAcbbgJHDWxYLfeU8+mOsMYmtnDo6N1yFWeewvLOlWvPqMsNgg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The fault path will immediately fail in handle_mm_fault(), so this is the minimal step which allows the per-VMA lock to be taken on file-backed VMAs. There may be a small performance reduction as a little unnecessary work will be done on each page fault. See later patches for the improvement. Signed-off-by: Matthew Wilcox (Oracle) --- mm/memory.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 2c7967632866..f2dcc695f54e 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5247,6 +5247,11 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address, goto out; } + if ((flags & FAULT_FLAG_VMA_LOCK) && !vma_is_anonymous(vma)) { + vma_end_read(vma); + return VM_FAULT_RETRY; + } + /* * Enable the memcg OOM handling for faults triggered in user * space. Kernel faults are handled more gracefully. @@ -5418,12 +5423,8 @@ struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm, if (!vma) goto inval; - /* Only anonymous vmas are supported for now */ - if (!vma_is_anonymous(vma)) - goto inval; - /* find_mergeable_anon_vma uses adjacent vmas which are not locked */ - if (!vma->anon_vma) + if (vma_is_anonymous(vma) && !vma->anon_vma) goto inval; if (!vma_start_read(vma)) -- 2.39.2