The patch titled
Preserve write permissions in migration entries
has been added to the -mm tree. Its filename is
preserve-write-permissions-in-migration-entries.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>
Implement the preservation of the write permissions. The preservation of
write permission avoids unnecessary COW operations following page
migration.
Signed-off-by: Christoph Lameter <clameter@xxxxxxx>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/linux/swap.h | 5 +++--
include/linux/swapops.h | 13 ++++++++++---
mm/migrate.c | 5 ++++-
mm/rmap.c | 2 +-
4 files changed, 18 insertions(+), 7 deletions(-)
diff -puN include/linux/swap.h~preserve-write-permissions-in-migration-entries include/linux/swap.h
--- devel/include/linux/swap.h~preserve-write-permissions-in-migration-entries 2006-04-14 22:03:19.000000000 -0700
+++ devel-akpm/include/linux/swap.h 2006-04-14 22:03:19.000000000 -0700
@@ -33,8 +33,9 @@ static inline int current_is_kswapd(void
#define MAX_SWAPFILES (1 << MAX_SWAPFILES_SHIFT)
#else
/* Use last entry for page migration swap entries */
-#define MAX_SWAPFILES ((1 << MAX_SWAPFILES_SHIFT)-1)
-#define SWP_TYPE_MIGRATION MAX_SWAPFILES
+#define MAX_SWAPFILES ((1 << MAX_SWAPFILES_SHIFT)-2)
+#define SWP_MIGRATION_READ MAX_SWAPFILES
+#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + 1)
#endif
/*
diff -puN include/linux/swapops.h~preserve-write-permissions-in-migration-entries include/linux/swapops.h
--- devel/include/linux/swapops.h~preserve-write-permissions-in-migration-entries 2006-04-14 22:03:19.000000000 -0700
+++ devel-akpm/include/linux/swapops.h 2006-04-14 22:03:19.000000000 -0700
@@ -69,15 +69,22 @@ static inline pte_t swp_entry_to_pte(swp
}
#ifdef CONFIG_MIGRATION
-static inline swp_entry_t make_migration_entry(struct page *page)
+static inline swp_entry_t make_migration_entry(struct page *page, int write)
{
BUG_ON(!PageLocked(page));
- return swp_entry(SWP_TYPE_MIGRATION, page_to_pfn(page));
+ return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,
+ page_to_pfn(page));
}
static inline int is_migration_entry(swp_entry_t entry)
{
- return unlikely(swp_type(entry) == SWP_TYPE_MIGRATION);
+ return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
+ swp_type(entry) == SWP_MIGRATION_WRITE);
+}
+
+static inline int is_write_migration_entry(swp_entry_t entry)
+{
+ return swp_type(entry) == SWP_MIGRATION_WRITE;
}
static inline struct page *migration_entry_to_page(swp_entry_t entry)
diff -puN mm/migrate.c~preserve-write-permissions-in-migration-entries mm/migrate.c
--- devel/mm/migrate.c~preserve-write-permissions-in-migration-entries 2006-04-14 22:03:19.000000000 -0700
+++ devel-akpm/mm/migrate.c 2006-04-14 22:03:19.000000000 -0700
@@ -167,7 +167,10 @@ static void remove_migration_pte(struct
inc_mm_counter(mm, anon_rss);
get_page(new);
- set_pte_at(mm, addr, ptep, pte_mkold(mk_pte(new, vma->vm_page_prot)));
+ pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
+ if (is_write_migration_entry(entry))
+ pte = pte_mkwrite(pte);
+ set_pte_at(mm, addr, ptep, pte);
page_add_anon_rmap(new, vma, addr);
out:
pte_unmap_unlock(pte, ptl);
diff -puN mm/rmap.c~preserve-write-permissions-in-migration-entries mm/rmap.c
--- devel/mm/rmap.c~preserve-write-permissions-in-migration-entries 2006-04-14 22:03:19.000000000 -0700
+++ devel-akpm/mm/rmap.c 2006-04-14 22:03:19.000000000 -0700
@@ -602,7 +602,7 @@ static int try_to_unmap_one(struct page
* pte is removed and then restart fault handling.
*/
BUG_ON(!migration);
- entry = make_migration_entry(page);
+ entry = make_migration_entry(page, pte_write(pteval));
}
set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
BUG_ON(pte_file(*pte));
_
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-add-migration-swap-entries-fix.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
preserve-write-permissions-in-migration-entries.patch
-
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