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 DE90B200B8 for ; Fri, 20 Oct 2023 17:23:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UQhrh7+6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6732C433C7; Fri, 20 Oct 2023 17:23:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697822600; bh=9DTH2ejZ6gRx9v5Kr+Y3Lfgwo0SmTNuA/A5IR8D58/Y=; h=From:To:Cc:Subject:Date:From; b=UQhrh7+6S/MSu4IcYRnXuy7EYcConABwkV5hydTwSyGaPGdbM+HMqPvgfmUEdx3Q2 2pBWW6qmhoe340ImjiAKa6WW0FD71QgmiHBHceMfRdW4VLA1W3NQyHUjHIXN+eXJP/ VlBL0uJMjRaOjf/o5PY5oVU6dzu7hzgNv6yKwCT7zH+CxhfMgHie2tydm/d+/n7S+N CZNwWgm3CF7e66+DDpUriULU2laVgMqusZkUK7RZkGYU/tb698rfmgSsfILGziBHQE brznPtN20sErmnwVXeT5lynnssIpxOJhevA05ao1A4x8QeQG4b4ek2Ioxqg1VwmSzs OZcVn5GEq5lGA== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , Jakub Acs , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 0/5] avoid divide-by-zero due to max_nr_accesses overflow Date: Fri, 20 Oct 2023 17:23:12 +0000 Message-Id: <20231020172317.64192-1-sj@kernel.org> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Changes from v1 (https://lore.kernel.org/damon/20231019194924.100347-1-sj@kernel.org/) - Add Reported-by: Jakub Acs The maximum nr_accesses of given DAMON context can be calculated by dividing the aggregation interval by the sampling interval. Some logics in DAMON uses the maximum nr_accesses as a divisor. Hence, the value shouldn't be zero. Such case is avoided since DAMON avoids setting the agregation interval as samller than the sampling interval. However, since nr_accesses is unsigned int while the intervals are unsigned long, the maximum nr_accesses could be zero while casting. Avoid the divide-by-zero by implementing a function that handles the corner case (first patch), and replaces the vulnerable direct max nr_accesses calculations (remaining patches). Note that the patches for the replacements are divided for broken commits, to make backporting on required tres easier. Especially, the last patch is for a patch that not yet merged into the mainline but in mm tree. SeongJae Park (5): mm/damon: implement a function for max nr_accesses safe calculation mm/damon/core: avoid divide-by-zero during monitoring results update mm/damon/ops-common: avoid divide-by-zero during region hotness calculation mm/damon/lru_sort: avoid divide-by-zero in hot threshold calculation mm/damon/core: avoid divide-by-zero from pseudo-moving window length calculation include/linux/damon.h | 7 +++++++ mm/damon/core.c | 12 +++--------- mm/damon/lru_sort.c | 4 +--- mm/damon/ops-common.c | 5 ++--- 4 files changed, 13 insertions(+), 15 deletions(-) base-commit: e845524c56a529768a8793e96304db09134eafdf -- 2.34.1