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Fri, 03 Apr 2026 02:50:20 -0700 (PDT) From: Liew Rui Yan To: yanquanmin1@huawei.com Cc: aethernet65535@gmail.com, damon@lists.linux.dev, linux-mm@kvack.org, sj@kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v3 1/2] mm/damon/lru_sort: validate min_region_size to be power of 2 Date: Fri, 3 Apr 2026 17:50:19 +0800 Message-ID: <20260403095019.29222-1-aethernet65535@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <8a902208-675d-4564-bb31-fdefcaebb752@huawei.com> References: <8a902208-675d-4564-bb31-fdefcaebb752@huawei.com> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Quanmin, On Fri, 3 Apr 2026 16:59:38 +0800 Quanmin Yan wrote: > [...] > > I'm a little confused, what does "causing kdamond to terminate > unexpectedly" mean? The damon_lru_sort_apply_parameters function will > eventually call damon_commit_ctx, and the power-of-2 check is always > performed. Is the early check here to prevent some more broken case > or am I missing something? terminate unexpectedly means - termination not initiated by the user. (e.g., not by echo N > enabled) The issue is not about whether the check exists, but about when it happens. In damon_commit_ctx(): dst->maybe_corrupted = true; if (!is_power_of_2(src->min_region_sz)) return -EINVAL; Even though -EINVAL is returned, the 'maybe_corrupted' flag has already been set. When kdamond sees this flag, it terminates. My patch prevents this by rejecting invalid 'min_region_sz' before damon_commit_ctx() is called, so 'maybe_corrupted' never gets set for invalid inputs. Best regards, Rui Yan