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=1792879916; b=f7qriGs5o9x7DuzcOJBhwQt5u7HuAAiiNrNwsRy2SAv0wp+3vd4l0LVW90E64E3Uozfg JMdX+cnSx3IjFQi8YhIecI+FcbWbNfrb9/csRce7UNLaBovERfFCAKWZxbNKCsAIpG1ZM 9K8ea5s/spINzx7LgPdMipH1z+JgMhq54hFfR254pbEUIjjid1Ep8+5aJ1P+YH8pU6KjZ 95/XpIXA8oqm4SFLq9eh9RDCFQ6sKkTXiUEDR+9w9ip68JNY+R0Re1zlZPmeWoSrkuTJ4 9cr76CNmGU+esLHdpcyhzhvv+kcmH9g0v59K2IwCfCJkTYxd+PeWGLkh6ipOzW1GbbA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792879916; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=Nkmr3kD+iOFE6eqQ744hZb3n/K7IlKbFrJJL5zbx4VQ=; b=3R6YIj8wJN+wFzhZ9ysm0Cd0HYariv0BUvoJc6ehH2luHEtiVi1jYeibIPlLnaf4X+yx oA/SlIawrjgFbuNdjdtfIWgtPSiqi279CdXmy3zxToMyUd7nzZTTqFKN4J+zTvA+fNCg8 1WhNZ3vIwjaptKO76TgfMIpZsfMOADZe+J0reJLR1/rocXB2V2ac2XxBpS4N0xooqoDCu 8igqfsXVpZl/uRAseldx1XZlxujmh6274LZXpIPVCF+tK3VjvOnhEZdEruoRX1tqW+7OY Oz5MCwRns/vU/15W37lRRTr4MPPQPyY757tRyIKWn70fW9uMWOCAp4Y2nhXhFkMIq2A== 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=iB9+h97l; 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 296E5606A326; Sat, 24 Oct 2026 22:11:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=iB9+h97l Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8DB491F01829; Sat, 24 Oct 2026 22:11:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792879915; bh=Nkmr3kD+iOFE6eqQ744hZb3n/K7IlKbFrJJL5zbx4VQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=iB9+h97lnqbFIUEl6O6yT3Xb13lPC+ZbQKXE9IlFhn5LhuWI8PD02Oz1MpQNBmJne oxNS8VI3btkX9YItlGn9QKGgatxCJcJp+QEyL2H2BehjH3PGGrgx1AKbirxeroFhai 74OdaAYjGNzDIl76wRdapycLGUfxnNFyOlnlaJDC8oXBo4B9LZeMVo3Tn5I7Iq8ay7 WPtsrf8y9mvV7a5IoazqW6LpKVNrvYvwW8OO5p01kW/Ij4M9W33S2AvTW1QXyNhyHn GsBrDgnTlOX2v7P4C3OzrbWJBWVH/J5EUYRPMGPfauTtPXegfAYePAyv1ul5HDqZfF I3HdFZacSjiqA== 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 v9 2/6] mm: expose WB_DONTCACHE_DIRTY in bdi debugfs stats Date: Sat, 24 Oct 2026 18:11:48 -0400 Message-ID: <20261024221152.6965-3-snitzer@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20261024221152.6965-1-snitzer@kernel.org> References: <20261024221152.6965-1-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 18e999053bae0..111b452629796 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