From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 CEAC433D4E4; Fri, 19 Jun 2026 20:51:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781902312; cv=none; b=ZHgBtc4wqKKVU/KkQAuWDIoRRYHYUeoao3s8m9UtT/PWhGzNb1enV5NC7EQwPZJInaTzUz63aizNInSpuW9wGfPRCTMYJZmmcgg+u4caAXVGxlYqSXlnUr/yvvSDBo6BKvBtnfkywHfHVUqXCyFu8BHbrhV8+Iqs6WDHZ69EwU0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781902312; c=relaxed/simple; bh=Gyz/K4csJI0UfKAbXzLIi3BIMnhcQOycKEtnC+z4rFY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=iXYakCG7tzGIfVSbAWCM9b+TWA6RMm5Jqt2XLxOvu55ZjisnNTI8rvx5uFVDMFCh4JBgZukHrKvBwwdAhPvq6DrDQi2xrVZoM4weyNXDVfaIJxQSPutFfVwnIdR4BHgL2IGFAKs5+Y7/aO3wIHFeAjSYSGmao21zWBs7O4XRR2k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=h1OovN4s; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="h1OovN4s" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB5F21F000E9; Fri, 19 Jun 2026 20:51:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781902311; bh=4iq0ijo90COF3Rq3DtHD6rw3T7Yg//ZMNQpyM055t7Q=; h=From:To:Cc:Subject:Date; b=h1OovN4sxY+yovVJ4XlVy27s5+y10ZuVfIBbIbydeh9OnbDkr+eYx8cPyiR3q5j+C GVikjWO2PHiS906CfWT4guAhMyn/S4moYzQKGLfmTi6xVj1/A7GbnYzzbg+3mLhdb7 R5Mp19yxBUCqaVpJPHTSBu+NO5PAJL2rrnib2acSYL7hO/NAvOOCToKF0lpH9LHf7W dVz9nlgef0HbkOQ8I1Y+oFjCMkMX+XRUwOqi5tzPYnEZymQ0hHWxQn3ZbEnK3ii3qe WqBbKxqdMrTHl8ChLcJ3yNEwNgrU6YxNdB275kEGLFGBJ6pZUbno+1gHg837V3574V OzZUHgQM0SYsQ== From: SeongJae Park To: Cc: SeongJae Park , "# 5 . 16 . x" , Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH] mm/damon: handle zero sampling interval in damon_max_nr_accesses() Date: Fri, 19 Jun 2026 13:51:43 -0700 Message-ID: <20260619205144.150664-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit damon_max_nr_accesses() causes divide-by-zero if sampling interval is zero. Fix it by handling the case. The issue was dicovered [1] by Sashiko. [1] https://lore.kernel.org/20260619202459.145010-1-sj@kernel.org Fixes: 198f0f4c58b9 ("mm/damon/vaddr,paddr: support pageout prioritization") Cc: # 5.16.x Signed-off-by: SeongJae Park --- include/linux/damon.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/damon.h b/include/linux/damon.h index 64d75c78f4df4..b6fbe6089abc6 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -1066,8 +1066,10 @@ static inline bool damon_target_has_pid(const struct damon_ctx *ctx) static inline unsigned int damon_max_nr_accesses(const struct damon_attrs *attrs) { + unsigned long sample_interval = attrs->sample_interval ? : 1; + /* {aggr,sample}_interval are unsigned long, hence could overflow */ - return min(attrs->aggr_interval / attrs->sample_interval, + return min(attrs->aggr_interval / sample_interval, (unsigned long)UINT_MAX); } base-commit: 7a58ae62cdf3c006a53b805bbb12079ab2621a07 -- 2.47.3