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h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Qjt3Df5dghFnppzxr1Z54A55GDwmn1BhOWImmYBXkhS00UI0huJ55xgj1k80c9ZCu /mjbrq+At/yTHDeZQp+bSHvshZA9aoGwJ7X+0tUTXv4FG+GvMM8z1DDKrH9VY42TnN 9iHcaDGvEo4uwo2agKjlBrNA6kO1bIAE399RxTyg= Date: Wed, 15 Oct 2025 12:59:11 -0700 From: Andrew Morton To: Dmitry Ilvokhin Cc: Shakeel Butt , Kemeng Shi , Kairui Song , Nhat Pham , Baoquan He , Barry Song , Chris Li , Axel Rasmussen , Yuanchu Xie , Wei Xu , Kiryl Shutsemau , Usama Arif , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, hughd@google.com, yangge1116@126.com, david@redhat.com Subject: Re: [PATCH v2] mm: skip folio_activate() for mlocked folios Message-Id: <20251015125911.0f0ebf87b278324667c4dfc5@linux-foundation.org> In-Reply-To: References: X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: btb4dhzen6gynqycoyqgg11mtp3cntim X-Rspamd-Queue-Id: 8B3881C000F X-Rspamd-Server: rspam09 X-HE-Tag: 1760558352-886639 X-HE-Meta: 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 OBTpBGza UqrP7 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 8 Oct 2025 18:06:07 +0000 Dmitry Ilvokhin wrote: > > > + * They might be still in mlock_fbatch waiting to be processed > > > + * and activating it here might interfere with > > > + * mlock_folio_batch(). __mlock_folio() will fail > > > + * folio_test_clear_lru() check and give up. It happens because > > > + * __folio_batch_add_and_move() clears LRU flag, when adding > > > + * folio to activate batch. > > > + */ > > > > This makes sense as activating an mlocked folio should be a noop but I > > am wondering why we are seeing this now. By this, I mean mlock()ed > > memory being delayed to get to unevictable LRU. Also I remember Hugh > > recently [1] removed the difference betwen mlock percpu cache and other > > percpu caches of clearing LRU bit on entry. Does you repro work even > > with Hugh's changes or without it? > > > > Thanks Shakeel for mentioning Hugh's patch, I was not aware of it. > Indeed, I could not reproduce problem on top of Hugh's patch anymore, > which totally make sense, because folio_test_clear_lru() is gone from > __folio_batch_add_and_move(). > > Now I wonder does folio_test_mlocked() check still make sense in the > current codebase? > > > [1] https://lore.kernel.org/all/05905d7b-ed14-68b1-79d8-bdec30367eba@google.com/ So I take it that this patch ("mm: skip folio_activate() for mlocked folios") is no longer needed?