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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rjeoH-00000000cJZ-3KmZ; Mon, 11 Mar 2024 12:31:17 +0000 Date: Mon, 11 Mar 2024 12:31:17 +0000 From: Matthew Wilcox To: Miaohe Lin Cc: linux-mm@kvack.org, Naoya Horiguchi , Andrew Morton Subject: Re: [PATCH 6/8] mm/memory-failure: Convert memory_failure() to use a folio Message-ID: References: <20240229212036.2160900-1-willy@infradead.org> <20240229212036.2160900-7-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: AACA31C0008 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: fm9azrj36tdixnqs8brbu3qxg8zn5ibk X-HE-Tag: 1710160283-922655 X-HE-Meta: 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 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 Fri, Mar 08, 2024 at 04:48:33PM +0800, Miaohe Lin wrote: > On 2024/3/1 5:20, Matthew Wilcox (Oracle) wrote: > > @@ -2277,8 +2277,8 @@ int memory_failure(unsigned long pfn, int flags) > > } > > } > > > > - hpage = compound_head(p); > > - if (PageTransHuge(hpage)) { > > + folio = page_folio(p); > > + if (folio_test_large(folio)) { > > /* > > * The flag must be set after the refcount is bumped > > * otherwise it may race with THP split. [...] > > @@ -2318,11 +2319,11 @@ int memory_failure(unsigned long pfn, int flags) > > * race window. If this happens, we could try again to hopefully > > * handle the page next round. > > */ > > - if (PageCompound(p)) { > > + if (folio_test_large(folio)) { > > folio_test_large() only checks whether PG_head is set but PageCompound() also checks PageTail(). > So folio_test_large() and PageCompound() are not equivalent? Assuming we have a refcount on this page so it can't be simultaneously split/freed/whatever, these three sequences are equivalent: 1 if (PageCompound(p)) 2 struct page *head = compound_head(p); 2 if (PageHead(head)) 3 struct folio *folio = page_folio(p); 3 if (folio_test_large(folio))