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Thu, 19 Mar 2026 17:16:22 +0100 (CET) From: Josh Law To: sj@kernel.org, akpm@linux-foundation.org Cc: damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Josh Law Subject: [PATCH 1/2] mm/damon/reclaim: reject non-power-of-2 addr_unit Date: Thu, 19 Mar 2026 16:16:19 +0000 Message-Id: <20260319161620.189392-2-objecting@objecting.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260319161620.189392-1-objecting@objecting.org> References: <20260319161620.189392-1-objecting@objecting.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-ZohoMailClient: External X-Stat-Signature: 7re8c6bkixfqh3ftyf93ew969ztc6iuc X-Rspamd-Server: rspam09 X-Rspam-User: X-Rspamd-Queue-Id: 8802F180019 X-HE-Tag: 1773936997-874621 X-HE-Meta: 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 cvepNhwn eE6GD6xvKf/s2c69Jcgt0wc7kYDMGHC+UPdGyhrcmkEE0RdfWcMrzwj6rJyFGdKxrSuPO+mhssLDE8WVlCK+fRAxw4i+SHoclse7uUDj4FlPp0paNNQgAiag2PPIROwNv+0R21GN9jkpVH3WJCxXoHgGoS2JjVksANZnwRkkZukMeGDi1vpsrS0f4Jy4C8jPJIuhza1l+TTqnxpr8uWWcMsHOdQ0zLZisk8YoTgWXx0pHL02USvHDgrgg7eCxCzGc7D4UGeFDbS+jFT4JTzn357pko4a6tGqk6Z/OyaTYP4HjU/DVnv250bNXdYI+4paZ9Sd+uprzx2AMcYeoGZecw+2jAvRW0gT0smiPYF+PNpEGP+ByYzTRLx1BLYsYiR8DUuCXNIscgGHlv8o= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: DAMON_MIN_REGION_SZ / addr_unit is used as min_region_sz, which is passed to ALIGN() and ALIGN_DOWN() in core.c. These macros require power-of-2 alignment. When addr_unit is not a power of 2 (e.g., 3), the division produces a non-power-of-2 min_region_sz, causing silent undefined behavior in ALIGN before damon_commit_ctx() gets a chance to reject it. Validate that addr_unit is a power of 2 in the store function so the user gets immediate -EINVAL feedback instead of a silent failure. Signed-off-by: Josh Law --- mm/damon/reclaim.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c index 43d76f5bed44..9b55df304e51 100644 --- a/mm/damon/reclaim.c +++ b/mm/damon/reclaim.c @@ -321,7 +321,7 @@ static int damon_reclaim_addr_unit_store(const char *val, if (err) return err; - if (!input_addr_unit) + if (!input_addr_unit || !is_power_of_2(input_addr_unit)) return -EINVAL; addr_unit = input_addr_unit; -- 2.34.1