From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 01 Jul 2004 12:05:43 +0900 From: IWAMOTO Toshihiro Subject: Re: [Lhms-devel] new memory hotremoval patch In-Reply-To: <1088640671.5265.1017.camel@nighthawk> References: <20040630111719.EBACF70A92@sv1.valinux.co.jp> <1088640671.5265.1017.camel@nighthawk> MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Message-Id: <20040701030543.8CE8F70A92@sv1.valinux.co.jp> Sender: owner-linux-mm@kvack.org Return-Path: To: Dave Hansen Cc: IWAMOTO Toshihiro , Linux Kernel Mailing List , lhms , linux-mm List-ID: At Wed, 30 Jun 2004 17:11:11 -0700, Dave Hansen wrote: > > On Wed, 2004-06-30 at 04:17, IWAMOTO Toshihiro wrote: > > Due to struct page changes, page->mapping == NULL predicate can no > > longer be used for detecting cancellation of an anonymous page > > remapping operation. So the PG_again bit is being used again. > > It may be still possible to kill the PG_again bit, but the priority is > > rather low. > > But, you reintroduced it everywhere, including file-backed pages, not > just for anonymous pages? Why was this necessary? Which PG_again check are you talking about? I think BUG_ON()s in file backed page codes should be kept for now. For swap pages, one possibility to reserve a special swap entry constant (SWAP_AGAIN) and check page->private instead of PageAgain check, but I'm not sure if this is a good idea. #define SWAP_AGAIN ~0UL ... static int do_swap_page(struct mm_struct * mm, struct vm_area_struct * vma, unsigned long address, pte_t *page_table, pmd_t *pmd, pte_t orig_pte, int write_access) { ... again: page = lookup_swap_cache(entry); ... mark_page_accessed(page); lock_page(page); if (page->private == SWAP_AGAIN) { ... goto again; } -- IWAMOTO Toshihiro -- 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: aart@kvack.org