Messages in this thread | | | Date | Thu, 01 Jul 2004 12:05:43 +0900 | From | IWAMOTO Toshihiro <> | Subject | Re: [Lhms-devel] new memory hotremoval patch |
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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; }
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