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 85B5D31A045; Sat, 21 Feb 2026 19:36:36 +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=1771702596; cv=none; b=APYwH0VXdUo4kWa1gMt2c5cU03HWA3Zj94+khGRyAHU9Il6tNGYhqLIWAjai4DLYf/ZpY++llHjTPwqIgsl43zu8wq2ZgU7EFJG7Ov0joPWK/sMDZXcVzL4XlETHjYpOVZkRkVg3IqOUA+umuthJFwcoQCkporQLU4maTX/qgEo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771702596; c=relaxed/simple; bh=eOXf1CiFbFTK2Hv2twtoei0dTOZocW8a2ac1D/Nl1gk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FfyabqOomnVKwc0u7rQ2QUeK8MFi2E/LlVr0zE+oB1tHy4kkRwN1k1oDU3picWHapYAlrgFM3lDkbToA9+6jL7wco/vl1R7KO+4q8g7wsCRpISN35DLQKWUd4ZWu7z6ssLwzlmfzXuarw/YrZGIl1fC7Qee0tlDiKWxvVd9McEc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MPXqH15g; 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="MPXqH15g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5034EC19422; Sat, 21 Feb 2026 19:36:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771702596; bh=eOXf1CiFbFTK2Hv2twtoei0dTOZocW8a2ac1D/Nl1gk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MPXqH15gc0vWx1tPY2KW4rtGZ3xtY9TJnGEj5MuuopIAYrIOE3Gp/u3xC7iyoW5s7 rizkeOvY3ymuZr33ZOXgI9Vbpj4B06UP+pawVuVfELd/rJ6Cb/F2xcvbZVoZrwj9h+ xb2hgK+T/98uptk7AL482fkl10Z71jQCFeVsTlclwNamegApuoDKwNjzKOCIxJ9N4Q P2CdS5fRyK3ijCp08GwtNlMdQ+Hj1ZwY46hycYwvF0IGVlWgQSaGuah1vbkLSkkhFC zmn5Bk20/RjYZZI/hBv3bm3X+lCy/AvlmNmvpZ/SMDo/GxmybDfaWYKNAqIr/TUr5V hz/2JUdRgX52Q== 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 06/10] mm/damon/core: add damon_merge_regions_of() debug_sanity check Date: Sat, 21 Feb 2026 11:36:23 -0800 Message-ID: <20260221193629.19332-7-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260221193629.19332-1-sj@kernel.org> References: <20260221193629.19332-1-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 | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 291a847a8c9bb..94be598cafef1 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -2545,6 +2545,22 @@ 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) +{ + if (r->nr_accesses == r->nr_accesses_bp / 10000) + return; + pr_err("nr_accesses (%u) != nr_accesses_bp (%u)\n", + r->nr_accesses, r->nr_accesses_bp); + WARN_ONCE(); +} +#else +static void damon_verify_merge_regions_of(struct damon_region *r) +{ +} +#endif + + /* * Merge adjacent regions having similar access frequencies * @@ -2565,6 +2581,8 @@ static void damon_merge_regions_of(struct damon_target *t, unsigned int thres, else r->age++; + damon_verify_merge_regions_of(r); + if (prev && prev->ar.end == r->ar.start && abs(prev->nr_accesses - r->nr_accesses) <= thres && damon_sz_region(prev) + damon_sz_region(r) <= sz_limit) -- 2.47.3