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Thu, 02 Apr 2026 22:29:20 -0700 (PDT) From: Liew Rui Yan To: sj@kernel.org Cc: yanquanmin1@huawei.com, damon@lists.linux.dev, linux-mm@kvack.org, Liew Rui Yan , stable@vger.kernel.org Subject: [PATCH v3 2/2] mm/damon/reclaim: validate min_region_size to be power of 2 Date: Fri, 3 Apr 2026 13:23:50 +0800 Message-ID: <20260403052837.58063-3-aethernet65535@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260403052837.58063-1-aethernet65535@gmail.com> References: <20260403052837.58063-1-aethernet65535@gmail.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The damon_commit_ctx() checks if 'min_region_sz' is a power-of-2. However, if an invalid input is provided via the DAMON_RECLAIM interface, the validation failure occurs too late, causing kdamond to terminate unexpectedly. To reproduce: 1. Enable DAMON_RECLAIM. 2. Set an invalid 'addr_unit' (e.g., addr_unit=3) so that 'min_region_sz = DAMON_MIN_REGION_SZ / addr_unit' becomes non-power-of-2. 3. Commit parameters, and observe kdamond termination. This patch adds an early check in damon_reclaim_apply_parameters() to validate 'min_region_sz' and return -EINVAL immediately if it is not a power-of-2, preventing unexpected kdamond termination. Fixes: 7db551fcfb2a ("mm/damon/reclaim: support addr_unit for DAMON_RECLAIM") Cc: # 6.18.x Signed-off-by: Liew Rui Yan --- mm/damon/reclaim.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c index 86da14778658..2747eef5919d 100644 --- a/mm/damon/reclaim.c +++ b/mm/damon/reclaim.c @@ -204,6 +204,11 @@ static int damon_reclaim_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_reclaim_mon_attrs.aggr_interval) { err = -EINVAL; goto out; -- 2.53.0