From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E6099CCF2E3 for ; Mon, 19 Oct 2026 13:46:40 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 09F1C6B0269; Mon, 19 Oct 2026 09:46:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 076BA6B026A; Mon, 19 Oct 2026 09:46:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EA8406B026B; Mon, 19 Oct 2026 09:46:39 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id C37E26B0269 for ; Mon, 19 Oct 2026 09:46:39 -0400 (EDT) Received: from smtpin17.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 64599406DC for ; Mon, 19 Oct 2026 13:46:39 +0000 (UTC) X-FDA: 85339500918.17.068D0B3 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf14.hostedemail.com (Postfix) with ESMTP id A17D7100009 for ; Mon, 19 Oct 2026 13:46:37 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=BqyE52BJ; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf14.hostedemail.com: domain of harry@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=harry@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1792417597; b=NK1tVAv247K5A2Gpxb55woyLZaPI/M4dT9Q4RiXalGYbyWx2wbDeoEq2drqWh5b4K4vs6M q1LibroZDVGmMwIFOI59Xy9fllqFidrkLxWu8kQ3pCH4IyiKU/G74mXHc1TPXikQC17xvl da77Kzjhevl0rwV5hsjT2ojtHlixxv4= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=BqyE52BJ; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf14.hostedemail.com: domain of harry@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=harry@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1792417597; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=GIOgXb/mnhZxFdGRsi0Jf0fYXTZWOZ0EseekTxOkjig=; b=M0JqRJHEYPWLiNgxN1g/xHF/MQYD9bFB51pM2ncGyGVzfi5U1xRl6X5t0BQxdubV5g27fg jy7hGLXg7EYkPGJ2EEsfSKzuHRUGjT6s4tq6uEE/Jif27zD/JLcEKyTcgOio5j/Dvq+OGq Dv6a1UqQkrj7ZQqkOSmoGdqRvlcOtKM= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id F288C60136; Mon, 19 Oct 2026 13:46:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 30BEE1F000C4; Mon, 19 Oct 2026 13:46:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792417596; bh=GIOgXb/mnhZxFdGRsi0Jf0fYXTZWOZ0EseekTxOkjig=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=BqyE52BJIudzcsDq5arU4VxZYP8jdANRgfaSAsySsr/SfWhoTbCY0S6zvW1kK3HPu GdDoQFIsAyEtKwjLr56Fj0KpDOKI9rkD/SKwuzSNgU5Y5RbnbQoqiq/b1nV4kIt1/i CoJECe7g8iRVAee7GK7AM/spZv5PaVNwfj6Tyib7OJf9/7/y1DiU25X7W/UNXEILvq CvQZbD9MU8dYkV9Z6DTgQB7up5xZhD8iLmj/TnFJ0u8I1yEHyLMKGaUJfmj6/BY40e gQ58Uq/U8gyY9kyUD0Je0VFboIlM8CtwDnxlyYvjtTuvpQsyp1WgQKqlx/LnYSTRsw wmInQsE/GIaMg== Date: Mon, 19 Oct 2026 14:46:34 +0100 From: Harry Yoo To: Kairui Song Cc: linux-mm@kvack.org, "Liam R. Howlett" , SJ Park , Andrew Morton , Johannes Weiner , Muchun Song , Qi Zheng , Ying Huang , Chris Li , Baoquan He , Nico Pache , Usama Arif , Michal Hocko , Roman Gushchin , Shakeel Butt , David Hildenbrand , Lorenzo Stoakes , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Vlastimil Babka , Suren Baghdasaryan , Kemeng Shi , Nhat Pham , Youngjun Park , Zi Yan , Gregory Price , "Matthew Wilcox (Oracle)" , Baolin Wang , Ryan Roberts , Dev Jain , Lance Yang , Hugh Dickins , David Rientjes , Yu Zhao , Vernon Yang , Zicheng Wang , Chen Ridong , Tal Zussman , Xiang Liu , Ehab Ababneh , zhaozhengzhuo , Lian Wang , Kunwu Chan , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, damon@lists.linux.dev Subject: Re: [PATCH v4 03/17] mm/memcg: add folio-based lruvec live helper Message-ID: References: <20261016-mglru-fg-v4-0-2106750c0bfa@tencent.com> <20261016-mglru-fg-v4-3-2106750c0bfa@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam07 X-Rspam-User: X-Rspamd-Queue-Id: A17D7100009 X-Stat-Signature: h65m57ef9xauzyk39tnup1igri3cxize X-HE-Tag: 1792417597-418439 X-HE-Meta: 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 bYGWWoVm 32CkcdxddER6isluujoZq6Y47+pCsFSTDl0V8f0V/xlAjZ9PCWwRGU0HBpVUWSD6lPp9BnE5V9s8YMcYy428EkR/VBIzZ/y0B08p3RVmzcPYKVlMhuRblw1fAs7mRBmKubLNVKKk37JxgprPdGKvQe9R2y6cyQqYYPkwgrzzK+eYbjJ0y3lZiFl6stQUZbo4iKfe17/8CkEzvFUMlS7J3u3qE0x5tGheCTHWO+2vCDqVfLJi4pV/F3U7SYSLIyhUC7KOifxBbiAuq+HLTjHATEzZvf292R4x9a2xHaRd3CfH6QxfjlGfOidJQ2jVycQl/3dVHcS7jSxQt9kzrKwfaj3FsIBlyUHnyHI2pcwaEOCWg5fgNe9ptG52RVJ+X2K4o8kIn2/CDqVv2PYBuT0o236uRaa+JBGLN4bd/bqfNF9rQOE8fVs4IcRNL3XNw2YUu+gDnYpOpQkO49fk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Oct 16, 2026 at 02:15:59PM +0800, Kairui Song wrote: > On Fri, Oct 16, 2026 at 3:11 AM Harry Yoo wrote: > > > > On Fri, Oct 16, 2026 at 02:15:52AM +0800, Kairui Song via B4 Relay wrote: > > > From: Kairui Song > > > > > > Add a helper that resolves a stable lruvec for a folio under RCU > > > without taking the lruvec lock. It takes a folio directly so the > > > lruvec lookup happens inside the RCU read-side critical section, > > > which a lruvec-based interface cannot guarantee. > > > > > > No functional change. > > > > > > Tested-by: zhaozhengzhuo > > > Signed-off-by: Kairui Song > > > --- > > > > This new helper is doing the the same thing as what > > get_non_dying_memcg_start/end() do. > > > > Hi Harry, thanks for letting me know, I wasn't aware this helper > exists, this series started before the re-planting work, so I missed > it. No worries! > But it's a bit different though, get_non_dying_memcg_start assumes the > caller holds a reference to memcg, while folio_lruvec_live_get only > assumes the caller holds an reference to the folio. Not sure I follow. I think get_non_dying_memcg_start() has the same assumption (a reference to the folio). A folio no longer pins the memcg, which was a key requirement for the reparenting work. In the function, RCU is the only mechanism that prevents release of the memcg and guarantees correct reparenting of local memcg stats (state_local) as it's reparented in an RCU work. > I'll check if I can deduplicate it though. Thanks! -- Cheers, Harry / Hyeonggon