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Sun, 29 Jun 2025 21:02:36 -0700 (PDT) MIME-Version: 1.0 References: <20250625-nr_writeback_removal-v1-1-7f2a0df70faa@suse.cz> In-Reply-To: From: Miklos Szeredi Date: Mon, 30 Jun 2025 06:02:25 +0200 X-Gm-Features: Ac12FXyOwr0llO8hHixJAlK1VoG5y6j39_v-eU55NPgRFJeCqE-U8vJRqvHmIrA Message-ID: Subject: Re: [PATCH] mm, vmstat: remove the NR_WRITEBACK_TEMP node_stat_item counter To: Jan Kara Cc: Joanne Koong , Vlastimil Babka , Andrew Morton , "Matthew Wilcox (Oracle)" , Tejun Heo , Maxim Patlasov , "Zach O'Keefe" , Jonathan Corbet , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Suren Baghdasaryan , Michal Hocko , "Kirill A. Shutemov" , Brendan Jackman , Johannes Weiner , Zi Yan , Jingbo Xu , Jeff Layton , Miklos Szeredi , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, Jens Axboe Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 31303120005 X-Stat-Signature: ai8cryezukn9o145b6gfaokqxrxny4ni X-HE-Tag: 1751256157-86162 X-HE-Meta: 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 xdwzbJfd lnLsxTeSHBAbEvgiGLM0RyPLIw8m9oKsbpJrHmlEk39ZmhAZoGsLaQmvx9CeuNez8CraPe/zR4WwInWBVCaMq/nU1EBXnY/PusoE2vzpoHKiKcyloLy492w0hgSR/vsxvbGonEdM1x6o6sXlOOcNS8qBtexCJlzDBoCck6t+GnELYGyUHx7CXX3gUdiMkjZh9SYj44cOV4To9eVTLtnjhNgNGgsFa2DTqBp3wWtqm4zQuvA52bV6Z4YqrGg== 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 Thu, 26 Jun 2025 at 09:01, Jan Kara wrote: > Regarding the comment, I'm frankly not certain how strictlimit solved > NR_WRITEBACK_TEMP issue because NR_WRITEBACK_TEMP was never included in any > computations there AFAICS. It just helped to limit amount of outstanding > dirty pages for FUSE mappings and thus indirectly limited the scope of > NR_WRITEBACK_TEMP issue. Anyway I think the sentence is obsolete now and > deleting it is indeed the right solution because FUSE writeback is now > properly accounted in the dirty limit. The question is how much fuse can overrun the dirty limit without strictlimit. AFAIU the strictlimit feature was added because temp pages were not accounted as "dirty" as opposed to writeback pages which were. Header of commit 5a53748568f7 ("mm/page-writeback.c: add strictlimit feature") has more details. But I don't fully understand all of that, and strictlimit may still be useful. Thanks, Miklos