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[99.254.144.39]) by smtp.gmail.com with ESMTPSA id mg9-20020a056214560900b006260e4b6de9sm1381429qvb.118.2023.06.09.13.45.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Jun 2023 13:45:46 -0700 (PDT) Date: Fri, 9 Jun 2023 16:45:44 -0400 From: Peter Xu To: Matthew Wilcox Cc: Suren Baghdasaryan , akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@suse.com, josef@toxicpanda.com, jack@suse.cz, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, michel@lespinasse.org, liam.howlett@oracle.com, jglisse@google.com, vbabka@suse.cz, minchan@google.com, dave@stgolabs.net, punit.agrawal@bytedance.com, lstoakes@gmail.com, hdanton@sina.com, apopple@nvidia.com, ying.huang@intel.com, david@redhat.com, yuzhao@google.com, dhowells@redhat.com, hughd@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, pasha.tatashin@soleen.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v2 2/6] mm: handle swap page faults under VMA lock if page is uncontended Message-ID: References: <20230609005158.2421285-1-surenb@google.com> <20230609005158.2421285-3-surenb@google.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Queue-Id: F38C040003 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: hrnb4hq97fh4d11sezussindikbb99d7 X-HE-Tag: 1686343549-676806 X-HE-Meta: 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 GEgYOhPD fLuzT1840447GEGzn8RBM3J9kCDG8Oztxt7Gs086TeaUEZvroM5pXT4NfzNyoDfACRvQwyWsS1mZ1y1NP7pCIy/5KJeWsTWKyr8z1Pf7XPdPF9TkV6+8hvLduwINhn8qsCSfMdifocPK905PUGXbSKgjINgiP/MVRd+CYRd6pO7uuIkUvgPrZrRJuThxopN+tBVnp5AqI0k9Z6Au+t8VtBNpEObHqscNSBZJlGsQbGMgmF/oE355ZawsKQmbCwqh9CQ/wOSdQ9ESYgO/O8VF6KHydcsuHlNIUQZh98MKJs+eWwkO5l2RbVzrZESyrJTmfkiylr7ntfOqFVt+LkDQ/UoKWaVV5ZRAe7ORdu1PHFQ7ROOaBboJQi61pVsdJj/7nXMfl6wFANBi6RTA= 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: On Fri, Jun 09, 2023 at 09:35:49PM +0100, Matthew Wilcox wrote: > On Fri, Jun 09, 2023 at 04:25:42PM -0400, Peter Xu wrote: > > > bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm, > > > unsigned int flags) > > > { > > > + /* Can't do this if not holding mmap_lock */ > > > + if (flags & FAULT_FLAG_VMA_LOCK) > > > + return false; > > > > If here what we need is the page lock, can we just conditionally release > > either mmap lock or vma lock depending on FAULT_FLAG_VMA_LOCK? > > See patch 5 ... Just reaching.. :) Why not in one shot, then? -- Peter Xu