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Shutemov" Cc: Jens Axboe , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, hannes@cmpxchg.org, clm@meta.com, linux-kernel@vger.kernel.org, bfoster@redhat.com, David Hildenbrand , Vlastimil Babka Subject: Re: [PATCH 04/11] mm: add PG_dropbehind folio flag Message-ID: References: <20241213155557.105419-1-axboe@kernel.dk> <20241213155557.105419-5-axboe@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: F277A20020 X-Stat-Signature: qk6qgpp573h31qpr3sgxi71fr36c9nbd X-Rspam-User: X-HE-Tag: 1734709528-849209 X-HE-Meta: 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 yyNw9Zxf qooV4mEaGY9TVCzhjHcgSsTYYNbHsbcW0BglRcOhpaeh8ptj1LX24S+QBDq/iLAtx3lt/HE2MkX5eYRlbuNpK+N6dCnezz/f6oh7eZrBWSVYsu21nmg9rrGnna5pwLrSZhFWp8CeUoOBh0d2woPZov1raktJQEWOjKosysHmTFVyBMJGaHtv1U9s56sGVG2vnqo2XzXk+/vjBCwWBxMA6M2ZyUvjCvITwDQNkiLPMro5gIaiVN6gZkCwlfs9W2TL++Owl8m9A/30z8XZEKvu2llMvRRjyv+NXDbCeiS3+VIBUH+E= 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 Fri, Dec 20, 2024 at 05:11:52PM +0200, Kirill A. Shutemov wrote: > On Fri, Dec 20, 2024 at 02:38:09PM +0000, Matthew Wilcox wrote: > > On Fri, Dec 20, 2024 at 01:08:39PM +0200, Kirill A. Shutemov wrote: > > > On Fri, Dec 13, 2024 at 08:55:18AM -0700, Jens Axboe wrote: > > > > Add a folio flag that file IO can use to indicate that the cached IO > > > > being done should be dropped from the page cache upon completion. > > > > > > > > Signed-off-by: Jens Axboe > > > > > > Reviewed-by: Kirill A. Shutemov > > > > > > + David, Vlastimil. > > > > > > I think we should consider converting existing folio_set_reclaim() / > > > SetPageReclaim() users to the new flag. From a quick scan, all of them > > > would benefit from dropping the page after writeback is complete instead > > > of leaving the folio on the LRU. > > > > Ooh, that would be nice. Removes the overloading of PG_reclaim with > > PG_readahead, right? > > Yep. Then ... maybe this series should just coopt the PG_reclaim flag for its purposes? Going through the users: lru_deactivate_file() --------------------- Called due to mapping_try_invalidate() failing to invalidate. Absolutely, get rid of this folio as quickly as possible. pageout() --------- Again, we're trying to get rid of this folio. This time due to memory pressure / reaching the end of the LRU list. Yup, we want it gone. shrink_folio_list() ------------------- Again, end of the LRU (both cases in this function) zswap_writeback_entry() ----------------------- This is exactly the same case that Jens is adding. The swapcache is being used as a staging location, and we want the folio gone as soon as writeback completes.