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bh=1+SeaVehwt396QnIHnWRn5MKZzC9W7QYhwhH8JQg6As=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=nsBBcQZvBukrCr6ZOO/LZhZdwZ2UeCaaLrXBy7YduO+XZ+qdB+zZcZ+70hLRx0iym LWa4m4h/8OIpWrMCwLZLT99KQSKS9bcqDa3xmfHUb8ym5/bamOIoBCQenlGGN0pZxq uzi6woLgmZBihfj+KoQpnX5OjJ8Mflm1N6HJR/Fyfwh4N1tELoKYDuTqvaJ5Hi2xy2 +4MpPG5mOginkJf5dRid4rPNyc+GBAlewpMLkGEKcBjfUxRgAFakPkadlrVoqEWY6v jsTKF7k2z1FXPHA5KwiowiwUo/Ifx4GCk1Dr5HFx9rZEgnwJZXrANlh9G7aHCwWRoV UjAC280UkaWSQ== From: Mike Snitzer To: Matthew Wilcox , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Cc: Chuck Lever , Jeff Layton , linux-nfs@vger.kernel.org, NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Christoph Hellwig , Jens Axboe , Jonathan Corbet Subject: [PATCH v10 3/7] mm: expose WB_DONTCACHE_DIRTY in bdi debugfs stats Date: Tue, 3 Nov 2026 16:17:50 -0500 Message-ID: <20261103211754.35352-4-snitzer@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20261103211754.35352-1-snitzer@kernel.org> References: <20261103211754.35352-1-snitzer@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: qqnz476scz66eymtrao5fkpwn693nidr X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 020C320009 X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1793740679-436827 X-HE-Meta: U2FsdGVkX191Ym3BEE8hQvJUcNvaLx74tHrax7bC/H2Tg9HkA2nfxNdvgpdtJqAqDdLbx3w745dSVZ5a4EEjTQI1BnzIsp5Iiq8vC12ttJcJ5BMRMpusqzutf3+W2lSf4ofVfj/zGNtI2WacOKH4Z8bfJ9pyJ4T90EERu8sOkHdRi2BiEOadrfG5DGD9jIXKdBT5w505FbLGHoiC1DrWmAyIafu5mKARMcSIRXkHNwn6F2kyP+XnM454f/h8jIukSjaOgKNBdWeb+dVf6hpHXBJ+b5vRAoHY7dqHIH1C+JniDtorpU5SdqIiYMvFwo+GlYIjGAiY7GKWGNjXJGBh9EzCQnHt2++xzcWpAF2KKWLxrN0t1NWRkUQAzbprhjG8vUO3YjpVjbbWI/Ndp9/f8YFs6SixUEdGBBmXK5GkwBS/apbBinfGLWr3BxpSEMPiczGip/2iaPYwfQ4EqkEf+FO4+eMeowtuKHRhp92vikv0rj2QfJWa/RXHfRDmThaaeOt3c53yvFlxgfc5KsRHiInLWsKHO6gUBgwrzZYq0TaHB+4I0UdhHoqvJi9z7HKTX0zZynpc+GCeUrg7ZxdTbnhmbMiCaBNTBv8uO0Upfq0QxAeFybnlSI1K1+Xdqpt5uZc0h1Y/rqY8Vt8bzWu7xa+2JLDtum6ehoxM7bF8g3x1/Tgmk4oVSGBe1JIjfmihCEx9sB7hEvoslsWP0NDTCDyCsTvby+7hkDk6RCtmvyKwEXcy1k89hIGKC6Ko0RoKISpOsNpZaZ2bZTE+xASL4B3ffDdS6HhNgTmwwfEOHuZAmTOrwHcKd4GU3zbh809zVRk9ItaPcyVHsY55cYANrWTx+cM0iF9tmJcgLqozKdmXzXSCt18G+TjBTqdHgXplY+JVGIk3lpVX45au0QlVha+5KS7yJVkHf/muNuaFb3Ees/tlVEI670492EL6K05VR73jp7rvlgOTFnhAV14 lcP5CGmO l+ITlcsIza5PgxmNESwvMh47R34r+eOSOVgRwUkykMk616DXm/+xI2hqiZizbfdMm6v2BqrwaP58iL9RpfR7Uz4UiK1CJV1tJoGLvEYPtH/9qS+Yw9dO2C6iSMWt0pRRv6IRQDU0dx4AWg+8p7bvR8Fc5RfDXgYrrjp0Dok6mc7LTfN/h6WeGuvechTKw7CLUjBwTUEangximeZDiDIgAh0iRNIpaRWXAVOCX9VGXTuxLdnvNyrzQnWH+Tbz7HR6wtPf2qC1sg55L3GH6MD3TjSgwcj4Twvq2I8bphKw528+A0BVYGWbqxEkx9ewTxlMzM5ADzwp0cT+4MJBVvD4/Owj8ou4ZdPUQUa3CJIe/xDMtxgQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 The per-bdi_writeback WB_DONTCACHE_DIRTY counter drives how much the flusher writes back in response to an IOCB_DONTCACHE kick, but it is not reported anywhere, so the DONTCACHE dirty backlog can only be inferred from MemFree/Cached movement. Report it as BdiDontcacheDirty in /sys/kernel/debug/bdi//stats and as WbDontcacheDirty in the per-wb stats, next to the Reclaimable line. Use wb_stat_sum() rather than wb_stat() to fold in the per-cpu batches: the flusher targets the summed value and small backlogs would otherwise read as zero. Fixes: 88d6f128d06d ("mm: track DONTCACHE dirty pages per bdi_writeback") Reviewed-by: Jeff Layton Signed-off-by: Mike Snitzer --- mm/backing-dev.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/backing-dev.c b/mm/backing-dev.c index fad1495d3b200..a09c21759fb9f 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -46,6 +46,7 @@ struct wb_stats { unsigned long nr_dirty_time; unsigned long nr_writeback; unsigned long nr_reclaimable; + unsigned long nr_dontcache_dirty; unsigned long nr_dirtied; unsigned long nr_written; unsigned long dirty_thresh; @@ -78,6 +79,7 @@ static void collect_wb_stats(struct wb_stats *stats, stats->nr_writeback += wb_stat(wb, WB_WRITEBACK); stats->nr_reclaimable += wb_stat(wb, WB_RECLAIMABLE); + stats->nr_dontcache_dirty += wb_stat_sum(wb, WB_DONTCACHE_DIRTY); stats->nr_dirtied += wb_stat(wb, WB_DIRTIED); stats->nr_written += wb_stat(wb, WB_WRITTEN); stats->wb_thresh += wb_calc_thresh(wb, stats->dirty_thresh); @@ -125,6 +127,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v) seq_printf(m, "BdiWriteback: %10lu kB\n" "BdiReclaimable: %10lu kB\n" + "BdiDontcacheDirty: %10lu kB\n" "BdiDirtyThresh: %10lu kB\n" "DirtyThresh: %10lu kB\n" "BackgroundThresh: %10lu kB\n" @@ -139,6 +142,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v) "state: %10lx\n", K(stats.nr_writeback), K(stats.nr_reclaimable), + K(stats.nr_dontcache_dirty), K(stats.wb_thresh), K(dirty_thresh), K(background_thresh), @@ -163,6 +167,7 @@ static void wb_stats_show(struct seq_file *m, struct bdi_writeback *wb, "WbCgIno: %10lu\n" "WbWriteback: %10lu kB\n" "WbReclaimable: %10lu kB\n" + "WbDontcacheDirty: %10lu kB\n" "WbDirtyThresh: %10lu kB\n" "WbDirtied: %10lu kB\n" "WbWritten: %10lu kB\n" @@ -179,6 +184,7 @@ static void wb_stats_show(struct seq_file *m, struct bdi_writeback *wb, #endif K(stats->nr_writeback), K(stats->nr_reclaimable), + K(stats->nr_dontcache_dirty), K(stats->wb_thresh), K(stats->nr_dirtied), K(stats->nr_written), -- 2.52.0