From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BE2463382D3; Sun, 1 Mar 2026 17:43:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772387012; cv=none; b=Q3xCHqqnKWUbPa99aDGW3oYmHM1kZZQbXUGe3byvZGM2VCn+7QkRD49A9yY6/44/UBuALlFL/+S7kHCmtfqIoAeoyv8n6B4K88ArlrFvYsC+Gl5JMzjZjCSw5G2hWEHt1FNNKgWP38NbfH4lcuK8L68OUXIpTH6lQUpOmzRLR8E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772387012; c=relaxed/simple; bh=lNQhvpFnr2Kehya342ovbJrx9ImZU409SPVoAQ9GUWs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cnLQCQIFwN9psOaq11dxVZiD7lhb0IPEDlCSecPvhP7qd46twUBwF5XfWu/7qUsk6mryzLYAzGZn4Hg6Fg+4zqsLGJm/73PJlunMy6hht9E6uPvUoHKYy2x40MfCwqCkQLMf3GaFMCwzQ/FZSso99BsMlGc6tCFM77bgHhYKi8U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ueWT0qzR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ueWT0qzR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A51CC2BC87; Sun, 1 Mar 2026 17:43:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772387012; bh=lNQhvpFnr2Kehya342ovbJrx9ImZU409SPVoAQ9GUWs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ueWT0qzREt2g1pwPwkGPIZTz9xG0/SvYZc6z93JT6hmlqnNe6AYJ88hvJ0Osz/ALy E+cT8yCe8UfCarWeZrYCVlEnuy3A19e6v/OvcnyE+UXporJywZr9NfE9RrF4eLTJwc etNMcHNx6RjLsli/LHgiwjSsggUKUZYC8mJbm9sH1AXrL+Xdrc6VP6/3eYKN/J/DbQ Q/oYNIDgbSLdlPdq1fllruUohQUJwpI4brKe/a2JUQwOVpWdVWiwzw3Vs+gqkiptw/ 9+Yu+VaVnQkXvfJLRP48fFbmGZQDd0+bDYAwQdcIQ5af96N0L22jpZ+SQRCgRvs9CV jmYUV4H9kK0Iw== From: SeongJae Park To: Cc: SeongJae Park , Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH v2 06/10] mm/damon/core: add damon_merge_regions_of() debug_sanity check Date: Sun, 1 Mar 2026 09:43:21 -0800 Message-ID: <20260301174327.76849-7-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260301174327.76849-1-sj@kernel.org> References: <20260301174327.76849-1-sj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit damon_merge_regions_of() should be called only after aggregation is finished and therefore each region's nr_accesses and nr_accesses_bp match. There were bugs that broke the assumption, during development of online DAMON parameter updates and monitoring results handling changes. Add a sanity check for that under CONFIG_DAMON_DEBUG_SANITY. Signed-off-by: SeongJae Park --- mm/damon/core.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 8a3738a17cdd9..93d1577b1ae07 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -2505,6 +2505,20 @@ static void damon_merge_two_regions(struct damon_target *t, damon_destroy_region(r, t); } +#ifdef CONFIG_DAMON_DEBUG_SANITY +static void damon_verify_merge_regions_of(struct damon_region *r) +{ + WARN_ONCE(r->nr_accesses != r->nr_accesses_bp / 10000, + "nr_accesses (%u) != nr_accesses_bp (%u)\n", + r->nr_accesses, r->nr_accesses_bp); +} +#else +static void damon_verify_merge_regions_of(struct damon_region *r) +{ +} +#endif + + /* * Merge adjacent regions having similar access frequencies * @@ -2518,6 +2532,7 @@ static void damon_merge_regions_of(struct damon_target *t, unsigned int thres, struct damon_region *r, *prev = NULL, *next; damon_for_each_region_safe(r, next, t) { + damon_verify_merge_regions_of(r); if (abs(r->nr_accesses - r->last_nr_accesses) > thres) r->age = 0; else if ((r->nr_accesses == 0) != (r->last_nr_accesses == 0)) -- 2.47.3