From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 5 Apr 2007 11:17:33 -0700 (PDT) From: Christoph Lameter Subject: Re: [RFC] Free up page->private for compound pages In-Reply-To: Message-ID: References: <20070405033648.GG11192@wotan.suse.de> <20070405035741.GH11192@wotan.suse.de> <20070405042502.GI11192@wotan.suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Hugh Dickins Cc: Nick Piggin , linux-mm@kvack.org, dgc@sgi.com List-ID: On Thu, 5 Apr 2007, Hugh Dickins wrote: > > static inline int page_count(struct page *page) > > { > > - if (unlikely(PageCompound(page))) > > - page = (struct page *)page_private(page); > > - return atomic_read(&page->_count); > > + return atomic_read(&compound_head(page)->_count); > > } > > No, you don't want anyone looking at the page_count of a page > currently under reclaim, or doing a get_page on it, to go veering > off through its page->private (page->first_page comes from another > of your patches, not in -mm). Looks like you need to add a test for > PageCompound in compound_head (what a surprise!), unfortunately. Hmmm... Thus we should really have separate page flag and not overload it? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org