From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794362173; b=H9I+VAwsfU5tExqIHwAa0KhtBDVClTVQOMmVHIHfozg6CfNFKVs1utDY/FhWwXlgTbXu 7dTh/R9essyLmEVgKe4Qye9/DCXjDzLVJF7ADjiUJ/9FZ6AfA5y4A02zOdS6K2Wrm3Sa7 dmBd7KFhrOYfvm9tlmumCl7bzlQMYsecG8E54KxOLlmBFroI6e7iNEllWN5tA8kROeKJm vZC9nzTknvJpWGoSgOwyWikl+kvTHddnAJPPX3Bd75P/Q/9xBM/eA9Q7M/JefDIi5UGN1 GFtAN+gOYOhXyKTZ1iSXfsD4npGTVf/rtm+UeSSuGYAzZXE3NHA6G0k1uGhdEVOUloA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794362173; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=1+SeaVehwt396QnIHnWRn5MKZzC9W7QYhwhH8JQg6As=; b=Ka9zPou9uvcBasW2z4X4VtJRWCuzIk6rEagjx/640LxVz85kgbmFTDfBq1ur3OHY2epW /YjlyXiKfhP6C6kZSdH9DChJoxexLcUwYVfGg+wgVCTLg/Kl86AcT9ljVSHRuf+VU8d9v c89BeYdOUtoqv72nEc0xjQ9xY4wOb9G0hnfnfIqiTpzBPZ04EhWBd9G0Fot+Acz5WFVob 2G7bSOFfTYwLni1RE0PtOU4H1I0H7qb8lbh5G2XBRCxptyYiWt9mVD5lsKcG/CubPpBNs cDpJGaj0lN7GGMceG87fgnMkN/MOvumI9mNmBXy163sOXyFYYJ0603cGhpk9BrJ7LgQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=jaYer3Uk; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0421A606A32A; Wed, 11 Nov 2026 01:56:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=jaYer3Uk Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9E4531F0089F; Wed, 11 Nov 2026 01:56:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794362172; bh=1+SeaVehwt396QnIHnWRn5MKZzC9W7QYhwhH8JQg6As=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=jaYer3UkU1XnKYfff4RTI5kdyEoXoydQ9Uq+hWH5QUV/6fm64O+SyKY6w6ncUO6km c/t8alJnoPITaNLCj6H+jafLoaNyVreEpXaR7luV87rWLQguNQvyv8X2O9jBeVcUpg Vy+26mUE7HSWj3mrNodWLmb2phg0BI9OPzd1UDIyVHE97cq8n0yqRTIDlY3OnC9D+L yUZiPvPWbJYYqLr6AKUYrOsu0S1ToFj+ewvRtBoXs4Uuk5G27EtO+rUD1O3XuUYQv5 s1464Z+iOs1zBIGgvFTMp7L2wTVcRaH8A+Iu0LhRJwbn/RT65spHtXg7DV//IsPZsk qInAFc8KCxg6A== From: Mike Snitzer To: Matthew Wilcox , Jan Kara , linux-mm@kvack.org, Christian Brauner , linux-fsdevel@vger.kernel.org Cc: Chuck Lever , Jeff Layton , linux-nfs@vger.kernel.org Subject: [PATCH v11 3/7] mm: expose WB_DONTCACHE_DIRTY in bdi debugfs stats Date: Tue, 10 Nov 2026 20:56:03 -0500 Message-ID: <20261111015607.46338-4-snitzer@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20261111015607.46338-1-snitzer@kernel.org> References: <20261111015607.46338-1-snitzer@kernel.org> X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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