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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id t22sm17623091pgm.18.2020.12.21.19.01.49 (version=TLS1 cipher=ECDHE-ECDSA-AES128-SHA bits=128/128); Mon, 21 Dec 2020 19:01:49 -0800 (PST) Date: Mon, 21 Dec 2020 19:01:37 -0800 (PST) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Alex Shi cc: Andrew Morton , Hugh Dickins , Johannes Weiner , Michal Hocko , Vladimir Davydov , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] mm/memcg: revise the using condition of lock_page_lruvec function series In-Reply-To: <1608186532-81218-1-git-send-email-alex.shi@linux.alibaba.com> Message-ID: References: <1608186532-81218-1-git-send-email-alex.shi@linux.alibaba.com> User-Agent: Alpine 2.11 (LSU 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 17 Dec 2020, Alex Shi wrote: > The series function could be used under lock_page_memcg(), add this and > a bit style changes following commit_charge(). > > Signed-off-by: Alex Shi > Cc: Hugh Dickins This patch, or its intention, Acked-by: Hugh Dickins but rewording suggested below, and requested above - which left me very puzzled before eventually I understood it. I don't think we need to talk about "a bit style changes", but the cross-reference to commit_charge() is helpful. " lock_page_lruvec() and its variants are safe to use under the same conditions as commit_charge(): add lock_page_memcg() to the comment. " > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Vladimir Davydov > Cc: Andrew Morton > Cc: cgroups@vger.kernel.org > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > --- > mm/memcontrol.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index b80328f52fb4..e6b50d068b2f 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1345,10 +1345,11 @@ void lruvec_memcg_debug(struct lruvec *lruvec, struct page *page) > * lock_page_lruvec - lock and return lruvec for a given page. > * @page: the page > * > - * This series functions should be used in either conditions: > - * PageLRU is cleared or unset > - * or page->_refcount is zero > - * or page is locked. > + * This series functions should be used in any one of following conditions: These functions are safe to use under any of the following conditions: > + * - PageLRU is cleared or unset > + * - page->_refcount is zero > + * - page is locked. Remove that full stop... > + * - lock_page_memcg() ... and, if you wish (I don't care), add full stop at the end of that line. Maybe reorder those to the same order as listed in commit_charge(). Copy its text exactly? I don't think so, actually, I find your wording (e.g. _refcount is zero) more explicit: good to have both descriptions. > */ > struct lruvec *lock_page_lruvec(struct page *page) > { > -- > 2.29.GIT