Use of the pte lock allows for much finer grained locking and avoids
the complexity coming with locking via the anon_vma. It will also
make the fetching of the pte value cleaner. Add a couple of other
improvements as well.
Signed-off-by: Christoph Lameter <[email protected]>
Index: linux-2.6.17-rc1-mm2/mm/memory.c
===================================================================
--- linux-2.6.17-rc1-mm2.orig/mm/memory.c 2006-04-14 14:47:37.000000000 -0700
+++ linux-2.6.17-rc1-mm2/mm/memory.c 2006-04-17 16:23:50.000000000 -0700
@@ -1881,7 +1881,7 @@ static int do_swap_page(struct mm_struct
entry = pte_to_swp_entry(orig_pte);
if (is_migration_entry(entry)) {
- migration_entry_wait(entry, page_table);
+ migration_entry_wait(mm, pmd, address);
goto out;
}
Index: linux-2.6.17-rc1-mm2/include/linux/swapops.h
===================================================================
--- linux-2.6.17-rc1-mm2.orig/include/linux/swapops.h 2006-04-14 14:47:37.000000000 -0700
+++ linux-2.6.17-rc1-mm2/include/linux/swapops.h 2006-04-17 16:45:52.000000000 -0700
@@ -91,13 +91,15 @@ static inline struct page *migration_ent
return p;
}
-extern void migration_entry_wait(swp_entry_t entry, pte_t *);
+extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
+ unsigned long address);
#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) { }
+static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
+ unsigned long address) { }
#endif
Index: linux-2.6.17-rc1-mm2/mm/migrate.c
===================================================================
--- linux-2.6.17-rc1-mm2.orig/mm/migrate.c 2006-04-14 14:47:37.000000000 -0700
+++ linux-2.6.17-rc1-mm2/mm/migrate.c 2006-04-17 16:46:45.000000000 -0700
@@ -180,48 +180,35 @@ out:
*
* This function is called from do_swap_page().
*/
-void migration_entry_wait(swp_entry_t entry, pte_t *ptep)
+void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
+ unsigned long address)
{
- struct page *page = migration_entry_to_page(entry);
- unsigned long mapping = (unsigned long)page->mapping;
- struct anon_vma *anon_vma;
- pte_t pte;
-
- if (!mapping ||
- (mapping & PAGE_MAPPING_ANON) == 0)
- return;
- /*
- * We hold the mmap_sem lock.
- */
- anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
+ pte_t *ptep, pte;
+ spinlock_t *ptl;
+ swp_entry_t entry;
+ struct page *page;
- /*
- * The anon_vma lock is also taken while removing the migration
- * entries. Take the lock here to insure that the migration pte
- * is not modified while we increment the page count.
- * This is similar to find_get_page().
- */
- spin_lock(&anon_vma->lock);
+ ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
pte = *ptep;
- if (pte_present(pte) || pte_none(pte) || pte_file(pte)) {
- spin_unlock(&anon_vma->lock);
- return;
- }
+ if (!is_swap_pte(pte))
+ goto out;
+
entry = pte_to_swp_entry(pte);
- if (!is_migration_entry(entry) ||
- migration_entry_to_page(entry) != page) {
- /* Migration entry is gone */
- spin_unlock(&anon_vma->lock);
- return;
- }
- /* Pages with migration entries must be locked */
+ if (!is_migration_entry(entry))
+ goto out;
+
+ page = migration_entry_to_page(entry);
+
+ /* Pages with migration entries are always locked */
BUG_ON(!PageLocked(page));
- /* Phew. Finally we can increment the refcount */
get_page(page);
- spin_unlock(&anon_vma->lock);
+ pte_unmap_unlock(ptep, ptl);
wait_on_page_locked(page);
put_page(page);
+ return;
+out:
+ pte_unmap_unlock(ptep, ptl);
}
/*
-
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