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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rsNjV-00000008BlB-1hxh; Thu, 04 Apr 2024 14:06:25 +0000 Date: Thu, 4 Apr 2024 15:06:25 +0100 From: Matthew Wilcox To: Peter Xu Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huacai Chen , David Hildenbrand , Jason Gunthorpe , Nathan Chancellor , Andrew Morton , WANG Xuerui , Ryan Roberts , loongarch@lists.linux.dev Subject: Re: [PATCH 1/3] mm: Allow anon exclusive check over hugetlb tail pages Message-ID: References: <20240403013249.1418299-1-peterx@redhat.com> <20240403013249.1418299-2-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 7064D1C0015 X-Stat-Signature: jhzw9yye66jgify97byqkx3nx1iryxh4 X-HE-Tag: 1712239591-625751 X-HE-Meta: U2FsdGVkX1/wdxkqrx9zwDqQQUp1aMvYBhR8Ua8AYp7hYnYtU0vpNG7KeH49Et5PUN2HumzHU3BsVEIOoRgTWpDlmp/JBoVb2Pf//MR/WZbT2zJIaVLZTddQVJ2PAc9LMGOYbGcRn8WVDPxQWyU6nyTK76GtborADVYV98GGhyNTiSpCmsqhSmE5kFLS12cMIO9hmtmD/HyOmjYJQ4E/XK4vv5eT2CjAGx3CPmTTyRkJH6+VRzhBz0SVZicvgw1aukHTB6HTx1z+gvnhycyd6jrsX2Q2xfUhHFNZntsGzCp+OusHrsPLNWlViWxf1UhYBhWWR6XnEU086eEGYP1RC0EBu2GB+AiuEWDYG08WaQ1vgwB/r18k319PMQmEIE6cQxvgLoPgAU+FymzHcPOPrXL8NopfGGM5Hym8VTIAaEbCIxoVXKVPwUKJaAycpXV6vSF4cT//1LEbcCwzjaw6zcO28sbgtd0cIx09s5etSLTzD9QtIIl0C23MmNlRKFqyJWYUGa+BG1Xtj6qt07IGGw9FYYCzaxkdzUfCZL+K9BBWXMCwZ4auBKCZEBeDIZRhAKaJTsxcuOQZC+sGDm3bGMAqh9yS/nppPcfVpv0iv6hh1cKDGFnLqqBDy6th5Z+ULpr+9eiRN/0qR1EDZufiaRcDJXSiMG148j8kGpplfVDxZd6Z8TcDctMdPlJ7JsA1ib4uQIKfUQuGV565wqAXSHU3yOf/OtDhZpZPpHXKzvRUymc/3w/HMiSLGIeGG6bsd4r9UARBCkrThS+V1AWm8d1eHVxJ5p8AC8qgSjxawfZAqWG3KVo0eJaebjHCMucUxNM3vioNEE6cVHxyUPooEQ== 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: List-Subscribe: List-Unsubscribe: On Thu, Apr 04, 2024 at 09:45:58AM -0400, Peter Xu wrote: > On Thu, Apr 04, 2024 at 01:05:57AM +0100, Matthew Wilcox wrote: > > if (PageHuge(page)) > > page = compound_head(page); > > I would think PageHead() check would help us to avoid compound_head() on > heads, which should still be the majority cases iiuc (assuming page->flags > is already around in the cache anyway). I've no strong opinion though, as > I can hardly tell a difference in reality. compound_head() includes a check for PageHead(). Adding the check just makes things slower.