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AJvYcCU7PaC+JATnkty4uJSKxdRTbTWoQAZpQ6AV5Hpe3W1WGBRflw3hbuTxAq8VwXryUt4cUIyojm/Cuw==@kvack.org X-Gm-Message-State: AOJu0Yyi7qK9Za23avlaTQfxhPtrx0Q029eo7MmOd9hzbsmcQrmxpmDh 9hMwVvXpgMVJoLkfWURhiu9U3me0k1Ji+doP69ffr1evisinbYOk X-Gm-Gg: ASbGncuMbxQi25DHU1YwyPY048SgHubq1CvlDw24sLJwxdcx3yNthcBNlpQx8ikZPLy lWQtKCduMK3sUtHApZlQXeNB0XrBF8bXSD5v44Q5w3McruAbUKgGT0q3gHPLDr08H2A0FLxztn9 j2z7cXzs+0QDFz5/e4IwDTWv1UvJs4FMOptuZC/U95WDiu1tO1e+NTopjXCo9NMMYZlhTGRUJ8+ wUCk+GLn/62MHdW3jhaRXTbM1Wf5lu2EbJvNN3JKz6J/SwIUdQNoS9+ X-Google-Smtp-Source: AGHT+IEgaLbnrjVv6I1Y7EY9cH+2jSO0oSHlg4dYQEAvICQBnLuGdXy6+f6dgsSlEJGV/JBAFg2eBQ== X-Received: by 2002:a17:906:d553:b0:ab3:ed0:cda with SMTP id a640c23a62f3a-ab30ed00dc1mr1793003366b.9.1737018623416; Thu, 16 Jan 2025 01:10:23 -0800 (PST) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ab2c9564857sm889892766b.96.2025.01.16.01.10.22 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 16 Jan 2025 01:10:22 -0800 (PST) Date: Thu, 16 Jan 2025 09:10:21 +0000 From: Wei Yang To: Suren Baghdasaryan Cc: Wei Yang , akpm@linux-foundation.org, peterz@infradead.org, willy@infradead.org, liam.howlett@oracle.com, lorenzo.stoakes@oracle.com, david.laight.linux@gmail.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mjguzik@gmail.com, oliver.sang@intel.com, mgorman@techsingularity.net, david@redhat.com, peterx@redhat.com, oleg@redhat.com, dave@stgolabs.net, paulmck@kernel.org, brauner@kernel.org, dhowells@redhat.com, hdanton@sina.com, hughd@google.com, lokeshgidra@google.com, minchan@google.com, jannh@google.com, shakeel.butt@linux.dev, souravpanda@google.com, pasha.tatashin@soleen.com, klarasmodin@gmail.com, corbet@lwn.net, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v9 11/17] mm: replace vm_lock and detached flag with a reference count Message-ID: <20250116091021.nm3nmmk2b2sd6hjj@master> Reply-To: Wei Yang References: <20250111042604.3230628-1-surenb@google.com> <20250111042604.3230628-12-surenb@google.com> <20250115025830.pebmoyerkruqtx5y@master> <20250115120532.mgvjhcrzvmmjasv7@master> <20250116013747.akajp2kdwhmbgq5r@master> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 4E8CD18000F X-Stat-Signature: u93j9xbazupox6nmxoesmx4in38rjh8d X-Rspam-User: X-HE-Tag: 1737018625-628209 X-HE-Meta: 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 TaOgnAfy 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.001884, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jan 15, 2025 at 05:41:27PM -0800, Suren Baghdasaryan wrote: [...] >> >> >the case of EAGAIN. >> >> > >> >> >> >> Looks good to me. >> >> >> >> >> >> >> >> Maybe we can compare the event VMA_LOCK_MISS and VMA_LOCK_ABORT >> >> >> to see the percentage of this case. If it shows this is a too rare >> >> >> case to impact performance, we can ignore it. >> >> >> >> >> >> Also the event VMA_LOCK_MISS recording is removed, but the definition is >> >> >> there. We may record it in the vma_start_read() when oldcnt is 0. >> >> >> >> >> >> BTW, the name of VMA_LOCK_SUCCESS confuse me a little. I thought it indicates >> >> >> lock_vma_under_rcu() successfully get a valid vma. But seems not. Sounds we >> >> >> don't have an overall success/failure statistic in vmstat. >> >> > >> >> >Are you referring to the fact that we do not increment >> >> >VMA_LOCK_SUCCESS if we successfully locked a vma but have to retry the >> >> >> >> Something like this. I thought we would increase VMA_LOCK_SUCCESS on success. >> >> >> >> >page fault (in which we increment VMA_LOCK_RETRY instead)? >> >> > >> >> >> >> I don't follow this. >> > >> >Sorry, I meant to say "in which case we increment VMA_LOCK_RETRY >> >instead". IOW, when we successfully lock the vma but have to retry the >> >pagefault, we increment VMA_LOCK_RETRY without incrementing >> >VMA_LOCK_SUCCESS. >> > >> >> Yes, this makes me confused about what VMA_LOCK_SUCCESS represents. > >I'll need to look into the history of why we account it this way but >this is out of scope for this patchset. > Agree. -- Wei Yang Help you, Help me