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[99.254.144.39]) by smtp.gmail.com with ESMTPSA id op29-20020a05620a535d00b0076c84240467sm3941292qkn.52.2023.08.15.12.24.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Aug 2023 12:24:18 -0700 (PDT) Date: Tue, 15 Aug 2023 15:24:16 -0400 From: Peter Xu To: "Matthew Wilcox (Oracle)" Cc: Andrew Morton , Jens Axboe , io-uring@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 8/9] mm: Rearrange page flags Message-ID: References: <20230815032645.1393700-1-willy@infradead.org> <20230815032645.1393700-9-willy@infradead.org> MIME-Version: 1.0 In-Reply-To: <20230815032645.1393700-9-willy@infradead.org> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: E241C180023 X-Stat-Signature: iz8u1g4mi94g94xocb1t8oi4swayzd9h X-Rspam-User: X-HE-Tag: 1692127463-585153 X-HE-Meta: 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 etChELao 2d3OotpfgcYEKYqc0sc3/P565U/uU36ABcMOLfyrEjf81sRWBa3BvIpQNM4AxOfYLFi+AK3ID8hgAuEmvDRmaAfO73n0L0Ttk/SCRwXm+CBTcuy0z2RGzXBLZzXIq2nBMQzO0cDPD3lyZJf0F2NAzLsUpHtmJq49pH/kj5/4GWe8h7xL1jiFtZ2vhwQiQ3ZM/tp4CVCBc8qBOfzElWnFANoM34xDu+bz+MyEmFwbmQSdoS306ryDEFgDASeDaTF0hot0sC8njc8X++RUyr+L64noh9/4qQLlMqBkH6qlQUmMRscDbjyHN3PKy8du2tAXZo2MXnFG0t9sS5Hc58IixOdvkCI55wxKkIut8o3qrLQ+Pqcw14DgaJlqDAM4Equ3/Qww4/HB8DvcvWL2v+tGUw1xdqDUytMN1Dp1f 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: On Tue, Aug 15, 2023 at 04:26:44AM +0100, Matthew Wilcox (Oracle) wrote: > Move PG_writeback into bottom byte so that it can use PG_waiters in a > later patch. Move PG_head into bottom byte as well to match with where > 'order' is moving next. PG_active and PG_workingset move into the second > byte to make room for them. > > Signed-off-by: Matthew Wilcox (Oracle) > --- > include/linux/page-flags.h | 24 +++++++++++------------- > 1 file changed, 11 insertions(+), 13 deletions(-) > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index aabf50dc71a3..6a0dd94b2460 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -99,13 +99,15 @@ > */ > enum pageflags { > PG_locked, /* Page is locked. Don't touch. */ > + PG_writeback, /* Page is under writeback */ > PG_referenced, > PG_uptodate, > PG_dirty, > PG_lru, > + PG_head, /* Must be in bit 6 */ Could there be some explanation on "must be in bit 6" here? Thanks, -- Peter Xu