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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rsAc9-00000006m5v-26wq; Thu, 04 Apr 2024 00:05:57 +0000 Date: Thu, 4 Apr 2024 01:05:57 +0100 From: Matthew Wilcox To: peterx@redhat.com 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: <20240403013249.1418299-2-peterx@redhat.com> X-Rspamd-Queue-Id: 3C0EB1C0016 X-Rspam-User: X-Stat-Signature: ixepwgyy9dj8newofnu9bck3tinwnk9b X-Rspamd-Server: rspam01 X-HE-Tag: 1712189161-813267 X-HE-Meta: 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 cRXgc19L 7n5vCcM61JLwNYqenS37KSgGYn8C0W/Fk35X9wZTzoBm+1S4uDdqzAutaAlEu9tkYY8/K6JRW/JFMHQsOQHgsF5ZClRJyf3xbBKkp9tcx0naLpmHnkQ9UrRyLkuhpuzDobZJxD/G7GwZ4s4QcSCy/NALNilCGpEhZEb6Q 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 Tue, Apr 02, 2024 at 09:32:47PM -0400, peterx@redhat.com wrote: > +++ b/include/linux/page-flags.h > @@ -1095,7 +1095,13 @@ PAGEFLAG(Isolated, isolated, PF_ANY); > static __always_inline int PageAnonExclusive(const struct page *page) > { > VM_BUG_ON_PGFLAGS(!PageAnon(page), page); > - VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page); > + /* > + * Allow the anon-exclusive check to work on hugetlb tail pages. > + * Here hugetlb pages will always guarantee the anon-exclusiveness > + * of the head page represents the tail pages. > + */ > + if (PageHuge(page) && !PageHead(page)) > + page = compound_head(page); I think this should be written as: /* * HugeTLB stores this information on the head page; THP keeps * it per page */ if (PageHuge(page)) page = compound_head(page); > return test_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags); > }