The patch titled
Wait for migrating page after incr of page count under anon_vma lock
has been added to the -mm tree. Its filename is
wait-for-migrating-page-after-incr-of-page-count-under-anon_vma-lock.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
From: Christoph Lameter <clameter@xxxxxxx>
Wait for migrating page after incr of page count under anon_vma lock
This patch replaces the yield() in do_swap_page with a call to
migration_entry_wait() in the migration code.
migration_entry_wait() locks the anonymous vma of the page and then safely
increments page count before waiting for the page to become unlocked.
Migration entries are only removed while holding the anon_vma lock
(See remove_migration_ptes). Therefore we can be sure that the
migration pte is not modified and the underlying page is not
removed while holding this lock.
Also make is_migration_entry() unlikely and clean up a unnecessary
BUG_ON.
Signed-off-by: Christoph Lameter <clameter@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/linux/swapops.h | 6 ++++--
mm/memory.c | 4 ++--
migrate.c | 0
3 files changed, 6 insertions(+), 4 deletions(-)
diff -puN include/linux/swapops.h~wait-for-migrating-page-after-incr-of-page-count-under-anon_vma-lock include/linux/swapops.h
--- devel/include/linux/swapops.h~wait-for-migrating-page-after-incr-of-page-count-under-anon_vma-lock 2006-04-14 22:09:01.000000000 -0700
+++ devel-akpm/include/linux/swapops.h 2006-04-14 22:09:01.000000000 -0700
@@ -77,7 +77,7 @@ static inline swp_entry_t make_migration
static inline int is_migration_entry(swp_entry_t entry)
{
- return swp_type(entry) == SWP_TYPE_MIGRATION;
+ return unlikely(swp_type(entry) == SWP_TYPE_MIGRATION);
}
static inline struct page *migration_entry_to_page(swp_entry_t entry)
@@ -88,14 +88,16 @@ static inline struct page *migration_ent
* corresponding page is locked
*/
BUG_ON(!PageLocked(p));
- BUG_ON(!is_migration_entry(entry));
return p;
}
+
+extern void migration_entry_wait(swp_entry_t, pte_t *);
#else
#define make_migration_entry(page) swp_entry(0, 0)
#define is_migration_entry(swp) 0
#define migration_entry_to_page(swp) NULL
+static inline void migration_entry_wait(swp_entry_t entry, pte_t *ptep) { }
#endif
diff -puN mm/memory.c~wait-for-migrating-page-after-incr-of-page-count-under-anon_vma-lock mm/memory.c
--- devel/mm/memory.c~wait-for-migrating-page-after-incr-of-page-count-under-anon_vma-lock 2006-04-14 22:09:01.000000000 -0700
+++ devel-akpm/mm/memory.c 2006-04-14 22:09:01.000000000 -0700
@@ -1880,8 +1880,8 @@ static int do_swap_page(struct mm_struct
entry = pte_to_swp_entry(orig_pte);
- if (unlikely(is_migration_entry(entry))) {
- yield();
+ if (is_migration_entry(entry)) {
+ migration_entry_wait(entry, page_table);
goto out;
}
diff -puN mm/migrate.c~wait-for-migrating-page-after-incr-of-page-count-under-anon_vma-lock mm/migrate.c
_
Patches currently in -mm which might be from clameter@xxxxxxx are
origin.patch
page-migration-make-do_swap_page-redo-the-fault.patch
slab-extract-cache_free_alien-from-__cache_free.patch
migration-remove-unnecessary-pageswapcache-checks.patch
migration-remove-unnecessary-pageswapcache-checks-fix.patch
swapless-v2-try_to_unmap-rename-ignrefs-to-migration.patch
swapless-v2-add-migration-swap-entries.patch
swapless-v2-make-try_to_unmap-create-migration-entries.patch
swapless-v2-rip-out-swap-portion-of-old-migration-code.patch
swapless-v2-revise-main-migration-logic.patch
wait-for-migrating-page-after-incr-of-page-count-under-anon_vma-lock.patch
preserve-write-permissions-in-migration-entries.patch
-
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