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AJvYcCWgn5BIdc17XDh8A9MAUfBR/WdApQ6+CHgJXbCW3LXlTZY2xiq44nbh9VCvTmz2PYwDERSUTq+nrQ==@kvack.org X-Gm-Message-State: AOJu0YxyEdPfvq1PQ+Dp2bpZL0JGwTspnuvQUUbo7X5ctatml7JYluRk 8D0JPki9DVN7mNT+PFXzlw5Qvaq7zZN9gM/1H3SynEbaid4VDGB8tFbbCUk3z+NKDQWyJKJjK7y +IkxhsvAprXzLuDjdI5nI+ihPCctF+ImeyQBQ9pAxtuiustB9ug== X-Google-Smtp-Source: AGHT+IHJknmAk8KebDgu9Yyb3Rxak+s+Kyaq1plzdl27i/1/yKnJoV65h8NfCSSqqdl5c90040R9iqfbEnXHxsjSq2A= X-Received: by 2002:a05:6102:440e:b0:4a3:c6f3:89d4 with SMTP id ada2fe7eead31-4a475f12a78mr5268274137.5.1728949662971; Mon, 14 Oct 2024 16:47:42 -0700 (PDT) MIME-Version: 1.0 References: <20241014221231.832959-1-weixugc@google.com> <20241014162730.fc48f2a53b89639a6207ba9d@linux-foundation.org> In-Reply-To: <20241014162730.fc48f2a53b89639a6207ba9d@linux-foundation.org> From: Wei Xu Date: Mon, 14 Oct 2024 16:47:30 -0700 Message-ID: Subject: Re: [PATCH 2/2] mm/mglru: reset page lru tier bits when activating To: Andrew Morton Cc: Yu Zhao , Brian Geffon , Jan Alexander Steffens , Suleiman Souhlal , Axel Rasmussen , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 69183A0012 X-Stat-Signature: reh6845gk8qh3ttxux5m8afz1dcyc6ge X-Rspam-User: X-HE-Tag: 1728949659-983349 X-HE-Meta: U2FsdGVkX18yEZyF/pMHHHYXb0/YloFl8Hn0F+BTUlPCluuOT0DsDTHkSx6DlrZnYPtm1UXENp8XPgO645p4WOIQ5/AdaagWrdt/5jgxoAscSPEPfkPp0hu9UdHMFva9IYy1jKaqRAVheXeo/4pcLnqVqB74apl0mmK8rnn5+YpW3ycaenFIbaTvR6yvz+YKpxwAyUOZ8lL8Ksny5utA08OQdGmKCmJTPAHBRdxaT8Wkzg+4o8BxiyxphFW5pk6+v2IYxxQGhfmEVINcPFa8hyY+j6JrV22uRlCzENQUbBauhUsG0nUUNQ11drrKhQKUjIBsqF30H3x56/VEoD3kmCAsbxafCdBVuiEceZE5KIbqk9ooKl3d4DEycknv50efdsqxYw5FZmOwhrPjxUFTs4abYOiK2xGD5eVtC/pgWbATPFEwqJJsHlp5cjnK6rpKrUr818plt4XbB3nwoAjwAv/BR9CRCv0ocnp9mprH2LCBeOpNWvqJ3Ce24u8OYDfvoXbRq+wDd7Hz0BsESu4x86nMy/WV2COqERDHikXl/+hJ/cEiodAfIh5DkMt1HM2FyTthu1VPJRPfe27r8JIkorsjGrdkTtpx0E1ArQj+WAr857gIYjQvB16/aS1G575LU9Y+BmMTl6VCOpHx8ceUgfZlFSTLlbUbWHHQlj9ME1NFr83HxZizcvVXgN+9YLpB6VeJtvRvLt5aNS+KtPKsOG6nRlRjeOq+HIFFfqjoV4NJr+RZSUeW/9CoL8BS0sZOnVk7tbKqiS/YnLMCWOa1iXdVstfJuxozkVe8dL36Gko/2gn1EzIkfbZnz1v2W2ysfmLHPhrfY1WVvdR+ROlg8cIPjldrXs6JiLe0cacfc42aj2bWS7FKM6XzLOxH4wPQW0GPQQI+RufKmv8qk5R1Axey77mfOcH7P28s61pXQHTXyfWM3528z8i6kWBufTUPmpuKcXgLLPrMoQqUSQS kfL5H8sX HcMSn9D8VPYDjZGgtWznPqPqR6GiY9iPoxmV0cPJ+t/NKObthBPO8BzDGwioAGYgwkCgjcDisZOMfkO90CSWoCKnU8ccm5G10uYGGiG1WmhVL1mDOYQ8Qo4zdCG1phn8CHWb7oAY1OL5gaAhta+CjypV1BRSVsZ4Q0LW9NcsF3qCmMbx3V2ECq4yKTWMjzkAv3c1srgzVIIyTuc8DDPxJ8KfNfkvH7DC9KafXyFohhPC5f6vFEbDLzHMEQodpl0YyhRglwFxP8JWK8Z8wOt8UkBY5Hw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000007, 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 Mon, Oct 14, 2024 at 4:27=E2=80=AFPM Andrew Morton wrote: > > On Mon, 14 Oct 2024 22:12:31 +0000 Wei Xu wrote: > > > folio_activate() calls lru_gen_add_folio() to move the folio to the > > youngest generation. But unlike folio_update_gen()/folio_inc_gen(), > > lru_gen_add_folio() doesn't reset the folio lru tier bits > > (LRU_REFS_MASK | LRU_REFS_FLAGS). Fix this inconsistency in > > lru_gen_add_folio() when activating a folio. > > What are the runtime effects of this flaw? It can affect how pages get aged via the MGLRU PID controller, though no bad behaviors clearly related to this have been detected at runtime. The fix is to address this inconsistency identified via code inspection.