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[109.81.83.7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47f85c531afsm52462450f8f.24.2026.07.27.04.07.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jul 2026 04:07:04 -0700 (PDT) Date: Mon, 27 Jul 2026 13:07:02 +0200 From: Michal Hocko To: Barry Song Cc: Ridong , Andrew Morton , Johannes Weiner , David Hildenbrand , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Zhongkun He , Muchun Song , Davidlohr Bueso , Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ridong Chen Subject: Re: [PATCH -v4 1/4] mm/vmscan: fix anon-only reclaim evicting file pages when swappiness=max Message-ID: References: <20260724033435.2573323-1-ridong.chen@linux.dev> <20260724033435.2573323-2-ridong.chen@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Stat-Signature: joekimsgaq6tqcktmsir3jrq4ttua7oc X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: E1866C000B X-HE-Tag: 1785150425-590238 X-HE-Meta: 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 EMiC0pFm lQNO/Ip6FYk3sZPZ1oAm3Wb8WMhzyCD4WF0IbdOt8dNbOic+ysqDGjLc9vw6B376bN7SxFK+Ol9UvCrdS04HigIXO2wHVl1GzFtl78aKWer2oZFcA5y4nG9gyQ7YtCtJGIRoiQ6BZ7a/ObldNXR1LZFf32/DshHgklfb086gxe7oWQwBNQw7kxnL30GP3j9+JtiSDi6PhU5vkv/FvHeRmSrH/hmBzYAuJk4PMD1nzFe3R7J3wRD0/OO1uBk9tEWLiNXMCG5FFIT8ZsjsmeWSuB7iTYbZKvlxJM/7IxsBhiLMnnEvbPBaZmdAM4X/N13To8Lj+dPo5OzRelD8F/lRyx/VSSdBG8X6lLr3b1Uk2zM6e6swn+9V5Zuj4fm7xNlz7j/+3SSfdMw19J3+Y0T0WEO6eHpkPIZdhGSs6bNHqP0FpRE3zG2rN42c1J+0POnxn97dxYaabA55kEeT5v1Mqg1W4FQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon 27-07-26 18:56:07, Barry Song wrote: > On Mon, Jul 27, 2026 at 4:19 PM Michal Hocko wrote: > > > > On Fri 24-07-26 11:34:32, Ridong wrote: > > > From: Ridong Chen > > > > > > As Qi mentioned [1], when swappiness=max (SWAPPINESS_ANON_ONLY) is set, > > > the reclaim logic is expected to reclaim anonymous pages exclusively. > > > However, due to the current ordering of checks in get_scan_count(), > > > file pages may still be evicted if can_reclaim_anon_pages() returns > > > false, which contradicts the semantics of SWAPPINESS_ANON_ONLY. > > > > But if can_reclaim_anon_pages tells us that anonymous pages are not > > reclaimable then it makes no sense to try that, no? What do you expect > > to see? An OOM killer? > > This is proactive reclaim rather than direct reclaim, and > SWAPPINESS_ANON_ONLY is only supported for proactive reclaim. It > therefore cannot invoke the OOM killer. > > If I understand correctly, this is exactly the issue this patch is > trying to address. Instead of falling back to reclaiming file folios, > it returns "bash: echo: write error: Resource temporarily unavailable". My bad. I have misread the changelog and even missed the WARN_ON for !pr-oactive reclaim path. Failing pro-active makes sense. -- Michal Hocko SUSE Labs