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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Axel Rasmussen , Yuanchu Xie , Wei Xu , Brendan Jackman , Johannes Weiner , Zi Yan , Lance Yang , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v10] mm/page_alloc: boost watermarks on atomic allocation failure Date: Tue, 17 Feb 2026 16:59:46 -0800 Message-ID: <20260218005947.2979-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260214-wujing-mm-page_alloc-v8-v10-1-bdfea431fd97@gmail.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: EB1B5A000B X-Stat-Signature: u57eoi6ftax8irkt61fusu3f7bm4o3yb X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1771376411-311335 X-HE-Meta: U2FsdGVkX1+0jfCjW8Wxn8qYqvinDD3Gvlw563wh1lB59SnWAezjpfWXCTQxEYaBmTrxA+uaRZwP+ggKr91IJ8IF4DXcIOIXL247N8NH8gUVuD79qawh9TRZwU7L/GAdVf8U34XGEa5L3csxSCHS2zxaiX7ykScQwvrGrJq+BT1NOkbdCzvGPddn6I452sByieN9gFm7iwrLcbgUjYr0TlA58bNl8LUSgUSU4RutcizPt4LmY37zzrj7Q5CCfcFv1y6sHh7kJC29FGnrkWBR7z+j5d+qRkMJ98aHhDJl2AVF6TPf4CZor9KsfajmV6H2lMG5iUfNN6UiGSMa31nhiVFjcgZApvqOlHwNmlNeqmlKLSEWzbFdBQXdkuFQItdsQUcwUcgq6Ksx+Ay0T6ATNkHplFS1GpyEIjWgByqZt5TTaq3DLce7h5HiZf61wYtcb/vhnbi34UoCeaz2aD8t6KfWXTCcMEMAnoEkehEvwQEuGZiR0x73Y3oD+Ikf6obvoyLT8QddktxfFgwAjUD+ifLMen497cYFTgNvACiZxVlCSxsAGNhbH1eT07181reqfExFy0xtEdPZispBparGGKAJ4TgX0jrHPJ0Wp9ORm3MWR2ITt7na8OlPfutzloIjy0FCtGRZfPq+mbeCK3GJP7ByoK+IrkXuFOu/rI/EfE6N6LJBPRLQbfIyvedThd+TJG79jVN8hZa1It4WLh+c62hyBxHfo9jDUN5b8VElWjaV3KxCpEZCbT9gIqZtEUuTE/s+Stefz9KLEqbOY8F1y3kBPUmdQtCeX7i4NmLQmywfvA9fuhHL8s11b91INeMuU0LDdLezYhnH7NFuF+zCjmVM1PwHFNBK+UbbmAU1Mod41vLWPX9ZA7/4zuY8bE2oOlmsUvatVw0WM4LVlhCKwCp7vsPYeeVcZZtT8HMFssTOIkY3vSrKjRHPjLzCd1myBf7W0JG4BHORH4ID2Wh t/ddMhDm aNbqw5v2oqBSFi93jqLAFFdkOdgqZxxKze//OxteO6UET8+K1BOLA2YBNSNJAo3iSrh6f3/QKoPepoOpvRhbNR26OvdF1c0Ombj3JbYT9Wq9coERXUaeIu1398YyhUP4fPQur+cUO3Uaw1VsEHEdOUTnpFqx7JDvfvCJmdFl1/HBypD0EBqyNusxZz9g5wmptz+s382xNSmMTWILLdxf7IlvdxjyoXHPlD89k1VTtfWFHdfK22lgPueCKk5HQnvFgjpI3KxMWqP4qLjuTsD7vlg1rVD9dcx876BY0VK2R+92Dxp8= 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 Sat, 14 Feb 2026 23:13:50 +0800 Qiliang Yuan wrote: > Atomic allocations (GFP_ATOMIC) are prone to failure under heavy memory > pressure as they cannot enter direct reclaim. > > Handle these failures by introducing a watermark boost mechanism for > atomic requests. Refactor boost_watermark() using an internal helper to > support both fragmentation and atomic paths. Apply zone-proportional > boosts (~0.1% of managed pages) for atomic allocations, while > decoupling it from watermark_boost_factor. > > Implement boost_zones_for_atomic() to iterate through and boost all > eligible zones in the zonelist, respecting nodemasks. Use a per-zone > 1-second debounce timer via last_boost_jiffies to prevent excessive > boosting. Protect modifications with zone->lock and verify with > lockdep. Integrate the mechanism into the page allocation slowpath > specifically for order-0 GFP_ATOMIC requests. > > This approach reuses existing infrastructure and ensures emergency > reserves even if fragmentation boosting is disabled. > > Allocation failure logs: > [38535644.718700] node 0: slabs: 1031, objs: 43328, free: 0 > [38535644.725059] node 1: slabs: 339, objs: 17616, free: 317 > [38535645.428345] SLUB: Unable to allocate memory on node -1, gfp=0x480020(GFP_ATOMIC) > [38535645.436888] cache: skbuff_head_cache, object size: 232, buffer size: 256, default order: 2, min order: 0 > [38535645.447664] node 0: slabs: 940, objs: 40864, free: 144 > [38535645.454026] node 1: slabs: 322, objs: 19168, free: 383 > [38535645.556122] SLUB: Unable to allocate memory on node -1, gfp=0x480020(GFP_ATOMIC) > [38535645.564576] cache: skbuff_head_cache, object size: 232, buffer size: 256, default order: 2, min order: 0 > [38535649.655523] warn_alloc: 59 callbacks suppressed > [38535649.655527] swapper/100: page allocation failure: order:0, mode:0x480020(GFP_ATOMIC), nodemask=(null) > [38535649.671692] swapper/100 cpuset=/ mems_allowed=0-1 > > Acked-by: Vlastimil Babka > Signed-off-by: Qiliang Yuan Acked-by: SeongJae Park Thanks, SJ [...]