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authorChristoph Lameter <clameter@sgi.com>2006-06-23 02:03:38 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-23 07:42:51 -0700
commit04e62a29bf157ce1edd168f2b71b533c80d13628 (patch)
tree7f0d5a58eeef2c2e08da86dc7141a1ccd050a37d /mm/rmap.c
parent442c9137de8d769053e81d325709dca72f0b5e44 (diff)
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[PATCH] More page migration: use migration entries for file pages
This implements the use of migration entries to preserve ptes of file backed pages during migration. Processes can therefore be migrated back and forth without loosing their connection to pagecache pages. Note that we implement the migration entries only for linear mappings. Nonlinear mappings still require the unmapping of the ptes for migration. And another writepage() ugliness shows up. writepage() can drop the page lock. Therefore we have to remove migration ptes before calling writepages() in order to avoid having migration entries point to unlocked pages. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/rmap.c')
-rw-r--r--mm/rmap.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 05d6d73a692..882a85826bb 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -596,6 +596,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
spin_unlock(&mmlist_lock);
}
dec_mm_counter(mm, anon_rss);
+#ifdef CONFIG_MIGRATION
} else {
/*
* Store the pfn of the page in a special migration
@@ -604,12 +605,22 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
*/
BUG_ON(!migration);
entry = make_migration_entry(page, pte_write(pteval));
+#endif
}
set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
BUG_ON(pte_file(*pte));
} else
+#ifdef CONFIG_MIGRATION
+ if (migration) {
+ /* Establish migration entry for a file page */
+ swp_entry_t entry;
+ entry = make_migration_entry(page, pte_write(pteval));
+ set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
+ } else
+#endif
dec_mm_counter(mm, file_rss);
+
page_remove_rmap(page);
page_cache_release(page);