Commit 4da5eda0 authored Jun 23, 2006 by Christoph Lameter Committed by Linus Torvalds Jun 23, 2006

[PATCH] Page Migration: Make do_swap_page redo the fault



It is better to redo the complete fault if do_swap_page() finds that the
page is not in PageSwapCache() because the page migration code may have
replaced the swap pte already with a pte pointing to valid memory.

do_swap_page() may interpret an invalid swap entry without this patch
because we do not reload the pte if we are looping back.  The page
migration code may already have reused the swap entry referenced by our
local swp_entry.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent cb2b95e1

mm/memory.c

+0 −7

Original line number	Diff line number	Diff line
		@@ -1879,7 +1879,6 @@ static int do_swap_page(struct mm_struct mm, struct vm_area_struct vma,
		goto out;

		entry = pte_to_swp_entry(orig_pte);
		again:
		page = lookup_swap_cache(entry);
		if (!page) {
		swapin_readahead(entry, address, vma);
		@@ -1903,12 +1902,6 @@ again:

		mark_page_accessed(page);
		lock_page(page);
		if (!PageSwapCache(page)) {
		/* Page migration has occured */
		unlock_page(page);
		page_cache_release(page);
		goto again;
		}

		/*
		* Back out if somebody else already faulted in this pte.

Admin message