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bh=hEn2zn5pWhG25VPBcYCkS7+7B1NjobplNjZ+d8XjyHk=; b=Z7Z2oquOcVjW4pJmDuhS4PCmqWkQmN4ZTLglervlpM6sz4XWXPrnbrYYOcptDtEK/J4L2P aw/szgb4YNCCWIpfffYybOI4psuXjq3nS1n9R32vhc7hXKgneXLlvYFkDn62NcxrcglkLv R0pfPXDko7G81Y/FUOKWkCUuQssm2dM= ARC-Authentication-Results: i=1; imf31.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=PesMaXNu; spf=pass (imf31.hostedemail.com: domain of sj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id AF83342A61; Sat, 27 Jun 2026 17:01:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 55E9F1F000E9; Sat, 27 Jun 2026 17:01:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782579666; bh=hEn2zn5pWhG25VPBcYCkS7+7B1NjobplNjZ+d8XjyHk=; h=From:To:Cc:Subject:Date; b=PesMaXNupjJJGZuvo+yqSgEunZs+pIOijrjAHoAz5KrDeHs0eigW5qDmImhC3o89x 3b05rCW3a4MZW5+hrLKEXgTaI6tudKUTTVvihDNtu3HdxuR1GuIj2Mzxgr6RiY1SWh MsmNSEeCYz2UitAgd6o8IWpfmoVHW0ELS1mJAMEDeDOzBRoNaW4L14iN1um4STbEmJ Rm6tlfZuBEb4TplCTLPpgBz2BYti0F6F65IB9CEOdRVIlh1MPC7NU+uakrRCaYMKC2 vxE+vucgP/CpLxAX0vYqKHLzaVSul7ngSaIxty8mvzcKvekNwYDXW7dmjT+X5k3KoU FpI7CLVly3dqw== From: SeongJae Park To: Cc: SeongJae Park , Andrew Morton , Yang Yingliang , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org Subject: [RFC PATCH] mm/damon/core: validate ranges in damon_set_regions() Date: Sat, 27 Jun 2026 10:00:56 -0700 Message-ID: <20260627170057.1867-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: j8m8myabsn13o8msfhr8zy9n876uo4rk X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: B236520009 X-HE-Tag: 1782579667-285207 X-HE-Meta: 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 KXvx+ly8 KiWg8S+4mC4icqJ45Ozq8qkgdCelQbpwzACgD0MSif1eOaIBfh/frDMXC3rwUgJmzOX8pBxwu+ObgRa6DY7IFVCi/16H9HSzgwuRu+JJxAWbxF+oeuVZLzdvhHoR1ZCXEclw5nONzrwKjJGkc7kcF2acs83a5F6PbRLDE0vYFPcXdQoTLMdH+W8VhCnf+MO/1tJ+Q5MkoxZgoYxxxBzMQcLArRwZHp8cQuWx9BjhcV+x9Y2BErvu8m5nz+Yz8aOaZx/Z45vc/1uWhQd2p6g+LsvP/nw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: DAMON core logic assumes zero length regions don't exist. However, a few DAMON API callers including DAMON_SYSFS, DAMON_RECLAIM and DAMON_LRU_SORT allow users to set empty monitoring target regions. This could result in WARN_ONCE() on CONFIG_DAMON_DEBUG_SANITY enabled kernel, and divide-by-zero from damon_merge_two_regions(). For example, the WANR_ONCE() can be triggered like below. # grep DAMON_DEBUG_SANITY /boot/config-$(uname -r) # CONFIG_DAMON_DEBUG_SANITY=y # damo start # cd /sys/kernel/mm/damon/admin/kdamonds/0 # echo 0 > contexts/0/targets/0/regions/0/start # echo 0 > contexts/0/targets/0/regions/0/end # echo commit > state # dmesg [....] [ 73.705780] ------------[ cut here ]------------ [ 73.707552] start 0 >= end 0 [ 73.708452] WARNING: mm/damon/core.c:359 at damon_new_region+0x6e/0x80, CPU#1: kdamond.0/758 [...] Disallow empty region user inputs by updating the validation logic. Fixes: 43b0536cb471 ("mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM)") Cc: # 5.16.x Signed-off-by: SeongJae Park --- mm/damon/core.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 7e4b9affc5b06..b3100d7fa5596 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -358,6 +358,11 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges, unsigned int i; int err; + for (i = 0; i < nr_ranges; i++) { + if (ranges[i].start >= ranges[i].end) + return -EINVAL; + } + /* Remove regions which are not in the new ranges */ damon_for_each_region_safe(r, next, t) { for (i = 0; i < nr_ranges; i++) { base-commit: f5cde2d41633df3fb1965efa00bfa827ca41836c -- 2.47.3