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Thu, 30 Apr 2026 18:37:40 -0700 (PDT) From: Liew Rui Yan To: SeongJae Park Cc: damon@lists.linux.dev, linux-mm@kvack.org, Liew Rui Yan Subject: [PATCH v5 1/2] mm/damon/lru_sort: validate min_region_size to be power of 2 Date: Fri, 1 May 2026 09:37:49 +0800 Message-ID: <20260501013750.71704-2-aethernet65535@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260501013750.71704-1-aethernet65535@gmail.com> References: <20260501013750.71704-1-aethernet65535@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 45E9540005 X-Stat-Signature: cs8ojb1ndrh1q9aabyu97utdfdcoys38 X-HE-Tag: 1777599462-464696 X-HE-Meta: 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 BvjqEsmZ 4TBnK37Y4J0dq9VE+LShrxrbqIF+qvhnAoEb/98iAcmKioCLxRgomyhGKm7sDnmTXCvH15fsdgtzrtQQcxLeNd9BCPZlTz32FH6YIicFyZfOWawTfDzbErAAraxj2QCTdcksnzXmaHUlUAkHIn2bVSRVCqcL8ZI8/GnZIIYuDOaU4pLAIlJhWoOdl+amM6h5edONot6uwmRIwMxzK1l7+3gAUvSGL2Kj8W16BXfWd3Qpuu40QiK5PDtRSPltrw4IMtIZNqaw0H0Rsg+SI2yoJTQqxabBobaWmZVp1y7aWRzi0/HB1rtQsKRc1a0Ne9thzHf2cg2Ofq8sdEGLxsCs2VzFQyRKRM1N1gc78ZdYBRzOp8PYWaKsxFO3uefWytg0qbqhpcETvb9+tDZHuomCJMOXj7bZoBMw/xEd80C/PS71P9AVhp3MnZx70FtoRFNj/A0t7KGZTDtzJa/vJKXnziV7jxA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Problem ======= When a user sets an invalid 'addr_unit' (e.g., 3) via DAMON_LRU_SORT, 'min_region_sz' becomes a non-power-of-2 value. While damon_commit_ctx() correctly detects this and returns -EINVAL, it sets the 'maybe_corrupted' flag during this process. This flag causes the running kdamond to terminate. While the termination is a safety measure, it is suboptimal in this case because the error is just a simple invalid input from the user, which shouldn't neccessitate stopping the kdamond. Reproduction ============ 1. Enable DAMON_LRU_SORT 2. Set addr_unit=3 3. Commit inputs via 'commit_inputs' 4. Observe kdamond termination Solution ======== Add an early validation in damon_lru_sort_apply_parameters() to check 'min_region_sz' before any state change occurs. If it is non-power-of-2, return -EINVAL immediately, preventing 'maybe_corrupted' from being set. Signed-off-by: Liew Rui Yan --- mm/damon/lru_sort.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c index 554559d72976..3fd176ef9d9c 100644 --- a/mm/damon/lru_sort.c +++ b/mm/damon/lru_sort.c @@ -294,6 +294,11 @@ static int damon_lru_sort_apply_parameters(void) param_ctx->addr_unit = addr_unit; param_ctx->min_region_sz = max(DAMON_MIN_REGION_SZ / addr_unit, 1); + if (!is_power_of_2(param_ctx->min_region_sz)) { + err = -EINVAL; + goto out; + } + if (!damon_lru_sort_mon_attrs.sample_interval) { err = -EINVAL; goto out; -- 2.53.0