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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> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 72006140002 X-Stat-Signature: w86a14b4qtzcnxb6mfyognfwsa6u6um1 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1775209822-143726 X-HE-Meta: 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 SiE4Ql9i 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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