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h=Date:From:To:Cc:Subject:References:In-Reply-To; b=hldADQWqF/hfs8SN4fmi7i5kP1AZdSlkfbJB/gbHkmwAWaZLmLnTQI0XrNAhIWA47 SIQ27wxt5GZOGMjM+hGvIcsLZezM0IfAan3a+ojz5ys8lj83KgGWDmo3+KNlosiyzO Iv65CgDxWAjl4ThF2wf0R3YuxZCpJ5P/LEkbLGIUXyj+Nj6hTfyninHN9PxUboAXj1 tosch+L2yJ3SvcbfAHkwv4RzLjJ92Ixhf9ABr9fittTCBl8UBNAekwKHaURP1h7l+8 cgr/k6MDgrv2IhX8a+N7Sz1HfNWKEVCRVCwc+mMXm/CFrWUpFcBvyTD9y/BRWZU62b BWhX3kD4uHg8g== Date: Tue, 22 Sep 2026 06:30:52 +0200 From: "Oscar Salvador (SUSE)" To: Joshua Hahn Cc: Hongfu Li , Muchun Song , Oscar Salvador , David Hildenbrand , Andrew Morton , Shakeel Butt , Michal Hocko , Roman Gushchin , Nhat Pham , Chris Down , Johannes Weiner , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Hongfu Li , stable@vger.kernel.org Subject: Re: [PATCH 2/2] mm/memcg: migrate per-node hugetlb lruvec stat together with hugetlb folio Message-ID: References: <20260922042054.3264663-1-joshua.hahnjy@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260922042054.3264663-1-joshua.hahnjy@gmail.com> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 3D0C71A0006 X-Rspam-User: X-Stat-Signature: a51zz4oc7pmt6386nemdanz7aqmnobww X-HE-Tag: 1790051460-793396 X-HE-Meta: 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 syeR0bZN Z9kdDXD3U+dpkDkDKQdBndBS5tTyBiMzYjBqQrgsevlUmwz0iE/QUkb9lqQjfq2QGjM1Q6ZTNGl/bLGOXHxUk7HNRfPhN4DwpXt3/euPazidEK3QvaEJkEdubTN/INx0Yexxx+muRgToEnHTn4NBbbhe+IkZDLa843GBrT+b4n9OB98ervrvEliQ/6p32MJENJ1WwPKfXQDg9k4vp/Fk7Y2K4rkRB2QuLdHMJ77PFwQtNW5CSQpNtrxCkXXbcaentVgFVzOB/0iqLn1J1s/KF5jJYfX1m6TY4k6hmS+kTknyKdpnOjVXqhGTJKQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Sep 21, 2026 at 09:20:53PM -0700, Joshua Hahn wrote: > On Tue, 22 Sep 2026 06:15:07 +0200 "Oscar Salvador (SUSE)" wrote: > > Why do we need the whole thing to be embraced by rcu? > > Hi Oscar, Hi Joshua, > > I believe it's because now getting the memcg from the objcg requires > an RCU lock to make sure it doesn't get removed while we work on the > memcg. I think this is since Qi Zheng's "Eliminate Dying Memory > Cgroup" series. Yes, I understood that obj_cgroup_memcg might need the rcu-dance, but I was unsure about the mod_memcg_lruvec_state() calls. -- Oscar Salvador SUSE Labs