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 522712EAFF for ; Thu, 19 Oct 2023 19:49:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Q/fE20KR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48C9FC433CA; Thu, 19 Oct 2023 19:49:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697744972; bh=JxnxpQi8Ul6nOhB30Sf8ttPU+Mbj0MwnPDqKZ/PALpM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Q/fE20KRyvJSGgRHegK3R+DBDTlM3NC4FaQxFC4fEJqSqwQHdqJucdhbh4cngKoMc 4Rii7MDRtomRT4L7TDzKSxzplwSoImsmMyfa3pLNK93O+F5ZWCTyb7IQdswuPcgchl 965fTzfU8pgybiLDqIrTq1WN72VSV27JSHJAoaMnrSmnzGcIde1GR1YtAwuXZXGr1W eg5GU5zj3caGORuA48hBOJgeswWu4AroqifVxo5HnxmR0uD99zC0Uig6ysPuqW9ijc ypsclOhxptVMU8Q7x6XKah1QWLn8ZPJiX2DEFntORfQiabj4NwIhRpZUTb/thUZHzA ufQlp0F+OjBaQ== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH 4/5] mm/damon/lru_sort: avoid divide-by-zero in hot threshold calculation Date: Thu, 19 Oct 2023 19:49:23 +0000 Message-Id: <20231019194924.100347-5-sj@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231019194924.100347-1-sj@kernel.org> References: <20231019194924.100347-1-sj@kernel.org> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When calculating the hotness threshold for lru_prio scheme of DAMON_LRU_SORT, the module divides some values by the maximum nr_accesses. However, due to the type of the related variables, simple division-based calculation of the divisor can return zero. As a result, divide-by-zero is possible. Fix it by using damon_max_nr_accesses(), which handles the case. Fixes: 40e983cca927 ("mm/damon: introduce DAMON-based LRU-lists Sorting") Cc: # 6.0.x Signed-off-by: SeongJae Park --- mm/damon/lru_sort.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c index 3ecdcc029443..f2e5f9431892 100644 --- a/mm/damon/lru_sort.c +++ b/mm/damon/lru_sort.c @@ -195,9 +195,7 @@ static int damon_lru_sort_apply_parameters(void) if (err) return err; - /* aggr_interval / sample_interval is the maximum nr_accesses */ - hot_thres = damon_lru_sort_mon_attrs.aggr_interval / - damon_lru_sort_mon_attrs.sample_interval * + hot_thres = damon_max_nr_accesses(&damon_lru_sort_mon_attrs) * hot_thres_access_freq / 1000; scheme = damon_lru_sort_new_hot_scheme(hot_thres); if (!scheme) -- 2.34.1