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(p200300d82f0a7f00fad73bc9069d031f.dip0.t-ipconnect.de. [2003:d8:2f0a:7f00:fad7:3bc9:69d:31f]) by smtp.gmail.com with ESMTPSA id 9sm16720849wmf.34.2021.08.09.00.25.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 09 Aug 2021 00:25:26 -0700 (PDT) Subject: Re: [RFC PATCH 11/15] mm/page_reporting: report pages at section size instead of MAX_ORDER. To: Zi Yan , linux-mm@kvack.org, Alexander Duyck Cc: Matthew Wilcox , Vlastimil Babka , "Kirill A . Shutemov" , Mike Kravetz , Michal Hocko , John Hubbard , linux-kernel@vger.kernel.org References: <20210805190253.2795604-1-zi.yan@sent.com> <20210805190253.2795604-12-zi.yan@sent.com> From: David Hildenbrand Organization: Red Hat Message-ID: Date: Mon, 9 Aug 2021 09:25:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210805190253.2795604-12-zi.yan@sent.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05.08.21 21:02, Zi Yan wrote: > From: Zi Yan > > page_reporting_order was set to MAX_ORDER, which is always smaller than > a memory section size. An upcoming change will make MAX_ORDER larger > than a memory section size. Set page_reporting_order to > PFN_SECTION_SHIFT to match existing size assumption. > > Signed-off-by: Zi Yan > Cc: David Hildenbrand > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > --- > mm/page_reporting.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/page_reporting.c b/mm/page_reporting.c > index 382958eef8a9..dc4a2d699862 100644 > --- a/mm/page_reporting.c > +++ b/mm/page_reporting.c > @@ -11,7 +11,8 @@ > #include "page_reporting.h" > #include "internal.h" > > -unsigned int page_reporting_order = MAX_ORDER; > +/* Set page_reporting_order at section size */ > +unsigned int page_reporting_order = PFN_SECTION_SHIFT; > module_param(page_reporting_order, uint, 0644); > MODULE_PARM_DESC(page_reporting_order, "Set page reporting order"); > > If you look closely, this is only a placeholder and will get overwritten in page_reporting_register(). I don't recall why we have the module parameter at all. Most probably, to adjust the reporting order after we already registered a user. Can't we just initialize that to 0 ? -- Thanks, David / dhildenb