From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f53.google.com (mail-ed1-f53.google.com [209.85.208.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E4DD647A878 for ; Tue, 13 Oct 2026 14:55:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791903330; cv=none; b=rXsGA88ouvHPIsuEzRjFKIF7q+C8K3WoX4gJblKFMRgDpdBI71bf6POvhaKY+S7S5IyQpSNyj3lCjKozhVZPyABzpLXrmAEoLX1eiAfAIs1NjTrU9elh6v5TuQFzFe+F7bMPMn6b7CPth19/8sSl/i1jO1HGyUM9L18XRQgteDw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791903330; c=relaxed/simple; bh=o+oFNcLpuYqRZRBrDMdI0bemVABEvrdGdfb8nMKpYCA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=m29DPWC9S2ZOZcpy9YV31qMuZlZWbrrcPnMhwRAdjumpVJ+vIPXE0GXOGR8JN5HujMrA1SviM5Z65sF3q+Zg6WKwD/9MrBn+kOtaWha4oa8KrAUCZllFXmIr/YxKZpSaUJk28kGRMY+pbU18/sCOlHKspia+5gKA8VAHVl+uFI8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=QBX0iTcE; arc=none smtp.client-ip=209.85.208.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="QBX0iTcE" Received: by mail-ed1-f53.google.com with SMTP id 4fb4d7f45d1cf-6b1b13e09ffso2914995a12.3 for ; Tue, 13 Oct 2026 07:55:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1791903327; x=1792508127; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=tAWkYGdqvifr12JtKIaB4bUGFJ5gXXZ5L73FeOEQvOQ=; b=QBX0iTcEDpOW7xzkX1ctaQfAM21OW6mzs+wy7rjAm+LXIWiDynJnPhdDCCzeQCbFN3 iyF0Dlmu5yRZStwXt52nb6Z0tYMDj0qQrnvK+yaouuj5SD+/P21mAUoEuKW0aa/OaBuT yP1JUFbBx8KazPTCAb+atDQPmXQ8KNhimS+tuv0ybqlMwOceDEqI9zE+HVVy2hpUToQe q3Apo32CnHe5tUFByNtnQwXBhlnnnOeYErBlCQd9x8CQZnxWnTOk+MSLDAqdpWvNM9Zv gaLQX291edvE8IKs8h6L3gqVkb7jiycQo6y/Ry/I0uzW4Gbtn/L04ce3JUOG6z5aGgNG nDcA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1791903327; x=1792508127; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=tAWkYGdqvifr12JtKIaB4bUGFJ5gXXZ5L73FeOEQvOQ=; b=rq9F+eK0y4bKM8JHByKJjSYkSGaNRW4YaegNz7HbBJ+pfkBZtwdtOjwqZhuJXphw79 EcOX6JwIh1JG1Q48DhrhPXpVzRPFy1Gf05Syc9CT4jDalbgAln63y75y5IxuIwu7e/X2 Sh4i5gJOHF5Ty8oa+JCjEbBAdLSeeU0I2/ja7CKGun1PPX0ecIfwk9dMZsvXpFiyLtfY SpPj6hIRTFpFeWnBv+9K8gW4emS8XomynWZC/A5gqz5kwKNPz6Epz8lwP9HEz8aYpNgJ zf0MshMfp7BInRKk48GXmWC/A5euFQSB9A/e1DYSy0QRnYIJPqcRb9rKN7EE2RAktQHx XUUQ== X-Forwarded-Encrypted: i=1; AKwUvBwpSKHpaibhq9zNGa2UPeGUldhbTnRADT4hK3grffqFPb4fj12+culqjeNuJmYEMRhMsDXqxQZHlWwEdCk=@vger.kernel.org X-Gm-Message-State: AFq9FYLkuGs/PF8i2q8HO4MWNoPXNu9D2KCW6MDnD9RMUJmb2tlas2X6 g8uSJpQ0vyO89z6JgELsnkUCYO7bfZtSphZ2XBJsDDuFpEku97T9I0nTQlDvpYNY X-Gm-Gg: AYBFou3aOJEYcyDSwcpylnjEO6qYClTfV9g0QHSeV4oGywSiI4QAxYDjXAueQI03p3R gqjcdobt8Qop1eedDPwAM5KQRT3lrC+n0dCZjFmpTP3gkOWFF9N4pnTLhgbusNJWTSblgGPllEd d/4PgNp/2CvaNWBc3kLyQ+LjBdZovGSv2fDxamiUd0LshcFBsQ5jnsxb2HQaEVt0r55vuUIpi4l IH4mIL4SwGQpZoBAkPrhyTpApoDiyaSEoCkmcBjjXtveIsuwCp8IMTFl7kqwViCznZ2vjQuJuiJ 9J63+i7sAuS22rQULp18thWk6q+pfetRLAjk0aZ5hM6jiXYvd4w1OqKa3f3Hbn/mi5HPKJV8nqe RENXWelJ1+fpbuqtliWo2JmJ1N0z32p+WDaQCQvH4f4RpOUJFb+uzCf0rDglGHH/sNT2TPa4reK ru8lhvhUzMtAYacdGz7WcUwUM1iLBL2qH3O0PJaapTbXef+i+Imx9NIiCBirYKUyDb9wLMrlfBW PkfE6PvbkIR6/uZkUVtLC1VCPDdkzbjZQTJBzAM8B0UBIuKZwqJvrpmgw== X-Received: by 2002:a05:6402:2351:b0:6b1:b626:5bd8 with SMTP id 4fb4d7f45d1cf-6b1b6265e1cmr5604234a12.0.1791903326983; Tue, 13 Oct 2026 07:55:26 -0700 (PDT) Received: from localhost.localdomain (87-205-122-125.dynamic.inetia.pl. [87.205.122.125]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6b179e03428sm6169161a12.37.2026.10.13.07.55.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Oct 2026 07:55:26 -0700 (PDT) From: Kyrylo Biryuk To: dm-devel@lists.linux.dev Cc: mpatocka@redhat.com, snitzer@kernel.org, agk@redhat.com, bmarzins@redhat.com, dlemoal@kernel.org, hare@suse.de, linux-kernel@vger.kernel.org Subject: [PATCH v5 2/4] dm zoned: do not reclaim a random zone into another random zone Date: Tue, 13 Oct 2026 16:55:20 +0200 Message-ID: <20261013145522.17499-3-illofspeed@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261013145522.17499-1-illofspeed@gmail.com> References: <20261013145522.17499-1-illofspeed@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit dmz_reclaim_rnd_data() falls back to a random destination zone when no free sequential zone is available and the target has cache zones. When the target is idle and the cache zone list is empty, dmz_get_rnd_zone_for_reclaim() selects random zones of the zoned device as well, so a random zone is then copied into another random zone. That frees nothing: the next pass picks the next random zone and copies it again, for as long as the target stays idle. Seen on a two-device target (256 GiB regular cache device plus a 27 TB host-managed drive) used as an md RAID5 member: after a full rebuild every chunk was mapped and no sequential zone was free, and the idle drive read and wrote about 72 MB/s each without pause for hours while the free zone counters in "dmsetup status" did not change. Reproduced on emulated host-managed drives (tcmu-runner ZBC handler): 340 MB/s of copying on an idle target, 0 MB/s with this patch. Only switch to a random destination zone when the zone being reclaimed is a cache zone: moving it to the zoned device still frees cache space. Fixes: c5c788595292 ("dm zoned: start reclaim with sequential zones") Reviewed-by: Damien Le Moal Assisted-by: LLM Signed-off-by: Kyrylo Biryuk --- drivers/md/dm-zoned-reclaim.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/md/dm-zoned-reclaim.c b/drivers/md/dm-zoned-reclaim.c index 315f0da99f3..88d56d3c86d 100644 --- a/drivers/md/dm-zoned-reclaim.c +++ b/drivers/md/dm-zoned-reclaim.c @@ -288,7 +288,13 @@ static int dmz_reclaim_rnd_data(struct dmz_reclaim *zrc, struct dm_zone *dzone) again: szone = dmz_alloc_zone(zmd, zrc->dev_idx, alloc_flags | DMZ_ALLOC_RECLAIM); - if (!szone && alloc_flags == DMZ_ALLOC_SEQ && dmz_nr_cache_zones(zmd)) { + /* + * If no free sequential zone is available, a cache zone can still be + * moved into a free random zone of the zoned device, which frees cache + * space. Do not do this for a random zone: moving it into another + * random zone frees nothing and, on an idle target, repeats forever. + */ + if (!szone && alloc_flags == DMZ_ALLOC_SEQ && dmz_is_cache(dzone)) { alloc_flags = DMZ_ALLOC_RND; goto again; } -- 2.43.0