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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2647bf5bf7asm63906485ad.1.2025.09.15.22.32.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Sep 2025 22:32:23 -0700 (PDT) Date: Mon, 15 Sep 2025 22:32:14 -0700 (PDT) From: Hugh Dickins To: Lance Yang cc: akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, ioworker0@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH mm-new 1/3] mm/khugepaged: skip unsuitable VMAs earlier in khugepaged_scan_mm_slot() In-Reply-To: <20250914143547.27687-2-lance.yang@linux.dev> Message-ID: References: <20250914143547.27687-1-lance.yang@linux.dev> <20250914143547.27687-2-lance.yang@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: C5FD81C000B X-Stat-Signature: uxcg1q6o3ednu6aps5y3c16cbzc7udj6 X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1758000745-709580 X-HE-Meta: U2FsdGVkX1/02qXjqcHVu/7tBzfm3w7t1Cbm7+Hg7Za2K8qL39PEiCk7Wix8v6n0cQ3frVJiz62VaGURIu3GXzxuBM26oPCIvpr2RHHwlzHwyZI+GLNzlla5YTgVHmVgoJQ4vZcMB+2zkNqw4ms8+CMvosTnd4uyE0GENGUdm5cqWnGRccQGDuSIAuaGKZKe4VJOKiPeEb2PwYqiBCTPy5tllzHRboVvkLkTitHFuxu5l+MNui1rTMNKIcVldncBxSJmxAZNAPAptDih8nR0wgyXJENh8KWjanr6sOBi4DD10KhHkM+nIl8CeMx98gT7wu//CoRe+w7K8yJ04iUIQljiCH0gOTLx/V79cxh0AyxVmL1miMIMWiiG354ZLnROSMisJUIxbD551llSXxBktN6cngUJjvrlXc80J2QeJxNuxOEcPbT085de/fLD+XS1T5e8wWlio/Z1iAE+Ht31rAnSgN7RST7myhNy6A+E462QiRh9+bOmQdvZYY0VnET5TvzMrL1f1fTPdOGN1hvUlOlTxd9foeYcTlTb8ow/XnfAV6SiPyGlrHnJG/LfL2soT2gFHDaCV53t/pqMMb/R51lnY818iGLjxLMf7P5H5vA3imDFDfTgEYtH2hE4Mf+8lnGIJkS1auxY3ub4LkP0/7sRx0bwudl4htGhrgj0qiXG0lOe0QmfGRwRSy0tU0R6PKeI0rgccJAACePy3ssKplEb8FLav8AF1KH55G0mjzQYhCCM6ttM2bNQJdGTCzmXkdCtsB+djG2IgIyUmuW7ZcFGQ3+z3tZgrOFzMLnYkXcIxoFGq8WsDC//ezuiR41o9WRS7tThyxew9mLXb6C2jiQ+rpg2mX6ADTsfX4SI9kNGChmL/WQRSfqoK0/tws8pIAv7FWS3SKJ4qc0gWeOVtpSlPscv0AVb7Vm/56/2PckZtKMbbyoq7YnBn6qfbLnoyXYsWz0wTyj8T/6Eh2f eSSvHJZJ 1syw14GTwNTDJqqrrAnoS9YBHeDCyVVmSpKwSPayugg43H1hiB9H2kej6XJS44CrFSR83jqXvbAEIQIFRzJHszqKkOUoa2sBt6sJXstwrIDdQRVLPLTdBXEDbDUvdsXyGsi2UIeUexvceAQODNDVaVMbmMEMh5+dsWmY6fTla/xVL8ucmly7CQ6dzIgS0wyxcuiaiQ0X2aZ/OEkUiP17KpolD7S7G2x9ChuSQgXIuie88ZuSlfUz0dpAifWy14CElZyp/75V30Uy/dRGMIs2hPXugYwU6O2C+/sUBxez3nRBtdQeKMNe3zzNKLJ+6jiSa5n1n+1F924g/cek75BydePQ9Nz3o0fnRNqtQeqQZp1jYgX7dXG5K2zPH4sgH4OAuNlspt6dWcDDt7gQPbNydYMKWGg== 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: List-Subscribe: List-Unsubscribe: On Sun, 14 Sep 2025, Lance Yang wrote: > From: Lance Yang > > Let's skip unsuitable VMAs early in the khugepaged scan; specifically, > mlocked VMAs should not be touched. Why? That's a change in behaviour, isn't it? I'm aware that hugepage collapse on an mlocked VMA can insert a fault latency, not universally welcome; but I've not seen discussion, let alone agreement, that current behaviour should be changed. Somewhere in yet-to-be-read mail? Please give us a link. Hugh