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bh=wQHa39SbYUNszRpbhZJPTtwB+DOrWIjoWgUc5UFfUZA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bcnzfZV0jfozeaH0PTAEYh1w4FxYSswdPyKtVUe7I5onhLQzYRsjcBsnJ6PfYwrUI /SQ7eb0aaKAOjJIFvmYp2mXykwN+0PIPFCZG81ZoL8i+ucysh3PFFL4CiaJkOLylcq 5A82Dfm4UtMfPFB4PHb5ucPYcMLmCd4Wb2dUIaeBii9chXlLnWoNyjyL4pKY1GPL9b UL8HpDBz4Dfa+0IDb2ZYKzw8TLZOz7pOzQDUoYzhhwsnE4cftsgRhvUPXk3n2MC9Fi lGqb7jVuOrqzH+0AYzeCZF9hfyftMY9YG2a2bgTJQcgGOgGgxbhxga40lLoj4gILKe ToZak5MabqyRg== From: SJ Park To: Liew Rui Yan Cc: SJ Park , Andrew Morton , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RESEND PATCH] mm/damon/tests/core-kunit: add test for unconditionally skipping the last region Date: Sat, 19 Sep 2026 09:07:25 -0700 Message-ID: <20260919160725.86256-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260919080453.628679-1-aethernet65535@gmail.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 145B1A000F X-Rspam-User: X-Stat-Signature: 81uu1k49kkpcetbp3g1wmxouqcbzmq4g X-HE-Tag: 1789834054-47865 X-HE-Meta: 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 eBMTUCHx UffJVSceTuFYtvmYm3B0z9w/AC5TBsB4NHwsCTo59Gv10sOAMvsUMLnSTPNkVokGHFbD1UVOOeK2XCCscsGsVw4CHx9jxG3zCnv14jqNJoYfaqrEJNQz6JohcIwpRrZgrbtRVbiXF3jtGrMGYPqLrW4aWTYw3WKcIlqG6F6vBtHshnKM1SjGdVdJOJmDOl+4XHZkkUbIG9ozC3iEDQaC7mpjy9EW9ErTfgM7U86/D/EZwpa9gkXaraKuE/qGi7CX/pxf40l9IojAx27ADPSAE/c20Iw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, 19 Sep 2026 16:01:58 +0800 Liew Rui Yan wrote: > Commit 50585192bc2e ("mm/damon/schemes: skip already charged targets and > regions") introduced a minor issue that causes the last region to be > skipped before it is processed. > > Example: > > 1. Target has 2 regions: R1 (0-100 bytes) and R2 (100-200 bytes). > 2. Quota is configured to process only 100 bytes per window. > 3. Window 1: Processes R1 (0-100). Quota is full. charge_{target, > addr}_from is saved at (Target, 100). > 4. Window 2: The loop reaches R2. Because R2 is > damon_last_region(t), the old code unconditionally returns true, > skipping R2 entirely and resetting the charge_{target,addr}_from. > > Result: R2 is permanently skipped even though it has never been > processed. > > Add a test to prevent this regression in the future. > > Signed-off-by: Liew Rui Yan Other than a trivial style that I commented below, Reviewed-by: SJ Park [...] > +static void damon_test_last_region_quota_reset(struct kunit *test) > +{ [...] > + t = damon_new_target(); > + if (!t) { > + kunit_skip(test, "target alloc fail"); > + } Let's drop braces for single line, as suggested [1] in coding-style. [1] https://docs.kernel.org/process/coding-style.html#placing-braces-and-spaces Thanks, SJ