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Fri, 28 Aug 2026 05:27:44 +0000 X-Mizu-Trace-ID: 1ed8bbe29e3740d6 X-Migadu-Flow: FLOW_OUT Date: Fri, 28 Aug 2026 13:27:38 +0800 From: Baoquan He To: Barry Song Cc: akpm@linux-foundation.org, linux-mm@kvack.org, axelrasmussen@google.com, baolin.wang@linux.alibaba.com, chenridong@xiaomi.com, david@kernel.org, hannes@cmpxchg.org, kasong@tencent.com, lianux.mm@gmail.com, linux-kernel@vger.kernel.org, ljs@kernel.org, lyugaofei@xiaomi.com, mhocko@kernel.org, qi.zheng@linux.dev, shakeel.butt@linux.dev, stevensd@chromium.org, wangzicheng@honor.com, weixugc@google.com, yuanchu@google.com Subject: Re: [PATCH 1/3] mm/mglru: improve readability of isolate_folios() Message-ID: References: <20260820045603.68809-1-baohua@kernel.org> <20260820045603.68809-2-baohua@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Stat-Signature: he1xboc1zhf8f3pt31m6ix9td3zh9wu8 X-Rspamd-Queue-Id: 19A56140003 X-Rspamd-Server: rspam02 X-Rspam-User: X-HE-Tag: 1787894875-648692 X-HE-Meta: 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 JdupP/Ef 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 08/28/26 at 11:22am, Barry Song wrote: > On Fri, Aug 28, 2026 at 11:15 AM Baoquan He wrote: > > > > On 08/20/26 at 12:56pm, Barry Song (Xiaomi) wrote: > > > From: Ridong Chen > > > > > > The for_each_evictable_type() loop in isolate_folios() > > > is misleading: it does not actually iterate over each > > > evictable type. Instead, get_type_to_scan() selects the > > > type to scan, while the iterator `i` merely bounds the > > > number of attempts. > > > > > > Make the fallback behavior explicit in the code and remove the > > > opaque for_each_evictable_type(i, swappiness). > > > > > > Signed-off-by: Ridong Chen > > > Co-developed-by: Barry Song (Xiaomi) > > > Signed-off-by: Barry Song (Xiaomi) > > > --- > > > mm/vmscan.c | 46 ++++++++++++++++++++++++++-------------------- > > > 1 file changed, 26 insertions(+), 20 deletions(-) > > > > The subject doens't reflect the truth. This patch changes the behaviour, > > but not improve readability of isolate_folios() only. > > > > I also noticed the confusion of isolate_folios() implementation, and made > > a patch to only change the local variable and added code comment to > > explain it in my local branch. Surely refactorying is also good. > > > > + * Scan at most one type per evictable type (anon/file), starting with > > + * the type get_type_to_scan() picked as statistically colder. > > + * > > + * After a scan: > > + * - isolated > 0: got folios, record the type and return. > > + * - scanned == 0: the type is empty; fall back to the other type. > > + * - otherwise: the type has folios but all were hot (or lost an > > + * isolate race); retry the same type rather than > > + * switch, so positive_ctrl_err()'s refault > > + * statistics stay unbiased. > > + */ > > > > While in Ridong's patch, the 3rd case disappeared. It doesn't rescan with > > the original type as the old code is doing, but return directly. > > > > right, the 3rd case comes back in patch 3/3: > https://lore.kernel.org/linux-mm/20260820045603.68809-4-baohua@kernel.org/ > > so i guess we can rename patch 1/3? Both is fine as long as thing is correct and clear, thanks.