[PATCH 3/6] mm: CONFIG_MMU for PG_mlocked

Hugh Dickins
2009-11-10T21:59:25Z

Remove three degrees of obfuscation, left over from when we had
CONFIG_UNEVICTABLE_LRU. MLOCK_PAGES is CONFIG_HAVE_MLOCKED_PAGE_BIT
is CONFIG_HAVE_MLOCK is CONFIG_MMU. rmap.o (and memory-failure.o)
are only built when CONFIG_MMU, so don't need such conditions at all.

Somehow, I feel no compulsion to remove the CONFIG_HAVE_MLOCK*
lines from 169 defconfigs: leave those to evolve in due course.

Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
---

include/linux/page-flags.h | 8 +++-----
mm/Kconfig | 8 --------
mm/internal.h | 26 ++++++++++++--------------
mm/memory-failure.c | 2 --
mm/page_alloc.c | 4 ----
mm/rmap.c | 17 +++++------------
6 files changed, 20 insertions(+), 45 deletions(-)

--- mm2/include/linux/page-flags.h 2009-11-02 12:32:34.000000000 +0000
+++ mm3/include/linux/page-flags.h 2009-11-04 10:52:58.000000000 +0000
@@ -99,7 +99,7 @@ enum pageflags {
PG_buddy, /* Page is free, on buddy lists */
PG_swapbacked, /* Page is backed by RAM/swap */
PG_unevictable, /* Page is "unevictable" */
-#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
+#ifdef CONFIG_MMU
PG_mlocked, /* Page is vma mlocked */
#endif
#ifdef CONFIG_ARCH_USES_PG_UNCACHED
@@ -259,12 +259,10 @@ PAGEFLAG_FALSE(SwapCache)
PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable)
TESTCLEARFLAG(Unevictable, unevictable)

-#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
-#define MLOCK_PAGES 1
+#ifdef CONFIG_MMU
PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked)
TESTSCFLAG(Mlocked, mlocked) __TESTCLEARFLAG(Mlocked, mlocked)
#else
-#define MLOCK_PAGES 0
PAGEFLAG_FALSE(Mlocked) SETPAGEFLAG_NOOP(Mlocked)
TESTCLEARFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked)
#endif
@@ -393,7 +391,7 @@ static inline void __ClearPageTail(struc

#endif /* !PAGEFLAGS_EXTENDED */

-#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
+#ifdef CONFIG_MMU
#define __PG_MLOCKED (1 << PG_mlocked)
#else
#define __PG_MLOCKED 0
--- mm2/mm/Kconfig 2009-11-02 12:32:34.000000000 +0000
+++ mm3/mm/Kconfig 2009-11-04 10:52:58.000000000 +0000
@@ -203,14 +203,6 @@ config VIRT_TO_BUS
def_bool y
depends on !ARCH_NO_VIRT_TO_BUS

-config HAVE_MLOCK
- bool
- default y if MMU=y
-
-config HAVE_MLOCKED_PAGE_BIT
- bool
- default y if HAVE_MLOCK=y
-
config MMU_NOTIFIER
bool

--- mm2/mm/internal.h 2009-09-28 00:28:41.000000000 +0100
+++ mm3/mm/internal.h 2009-11-04 10:52:58.000000000 +0000
@@ -63,17 +63,6 @@ static inline unsigned long page_order(s
return page_private(page);
}

-#ifdef CONFIG_HAVE_MLOCK
-extern long mlock_vma_pages_range(struct vm_area_struct *vma,
- unsigned long start, unsigned long end);
-extern void munlock_vma_pages_range(struct vm_area_struct *vma,
- unsigned long start, unsigned long end);
-static inline void munlock_vma_pages_all(struct vm_area_struct *vma)
-{
- munlock_vma_pages_range(vma, vma->vm_start, vma->vm_end);
-}
-#endif
-
/*
* unevictable_migrate_page() called only from migrate_page_copy() to
* migrate unevictable flag to new page.
@@ -86,7 +75,16 @@ static inline void unevictable_migrate_p
SetPageUnevictable(new);
}

-#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
+#ifdef CONFIG_MMU
+extern long mlock_vma_pages_range(struct vm_area_struct *vma,
+ unsigned long start, unsigned long end);
+extern void munlock_vma_pages_range(struct vm_area_struct *vma,
+ unsigned long start, unsigned long end);
+static inline void munlock_vma_pages_all(struct vm_area_struct *vma)
+{
+ munlock_vma_pages_range(vma, vma->vm_start, vma->vm_end);
+}
+
/*
* Called only in fault path via page_evictable() for a new page
* to determine if it's being mapped into a LOCKED vma.
@@ -144,7 +142,7 @@ static inline void mlock_migrate_page(st
}
}

-#else /* CONFIG_HAVE_MLOCKED_PAGE_BIT */
+#else /* !CONFIG_MMU */
static inline int is_mlocked_vma(struct vm_area_struct *v, struct page *p)
{
return 0;
@@ -153,7 +151,7 @@ static inline void clear_page_mlock(stru
static inline void mlock_vma_page(struct page *page) { }
static inline void mlock_migrate_page(struct page *new, struct page *old) { }

-#endif /* CONFIG_HAVE_MLOCKED_PAGE_BIT */
+#endif /* !CONFIG_MMU */

/*
* Return the mem_map entry representing the 'offset' subpage within
--- mm2/mm/memory-failure.c 2009-11-02 12:32:34.000000000 +0000
+++ mm3/mm/memory-failure.c 2009-11-04 10:52:58.000000000 +0000
@@ -582,10 +582,8 @@ static struct page_state {
{ unevict|dirty, unevict|dirty, "unevictable LRU", me_pagecache_dirty},
{ unevict, unevict, "unevictable LRU", me_pagecache_clean},

-#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
{ mlock|dirty, mlock|dirty, "mlocked LRU", me_pagecache_dirty },
{ mlock, mlock, "mlocked LRU", me_pagecache_clean },
-#endif

{ lru|dirty, lru|dirty, "LRU", me_pagecache_dirty },
{ lru|dirty, lru, "clean LRU", me_pagecache_clean },
--- mm2/mm/page_alloc.c 2009-11-02 12:32:34.000000000 +0000
+++ mm3/mm/page_alloc.c 2009-11-04 10:52:58.000000000 +0000
@@ -487,7 +487,6 @@ static inline void __free_one_page(struc
zone->free_area[order].nr_free++;
}

-#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
/*
* free_page_mlock() -- clean up attempts to free and mlocked() page.
* Page should not be on lru, so no need to fix that up.
@@ -503,9 +502,6 @@ static inline void free_page_mlock(struc
__dec_zone_page_state(page, NR_MLOCK);
__count_vm_event(UNEVICTABLE_MLOCKFREED);
}
-#else
-static void free_page_mlock(struct page *page) { }
-#endif

static inline int free_pages_check(struct page *page)
{
--- mm2/mm/rmap.c 2009-11-04 10:52:52.000000000 +0000
+++ mm3/mm/rmap.c 2009-11-04 10:52:58.000000000 +0000
@@ -787,7 +787,7 @@ static int try_to_unmap_one(struct page
ret = SWAP_MLOCK;
goto out_unmap;
}
- if (MLOCK_PAGES && TTU_ACTION(flags) == TTU_MUNLOCK)
+ if (TTU_ACTION(flags) == TTU_MUNLOCK)
goto out_unmap;
}
if (!(flags & TTU_IGNORE_ACCESS)) {
@@ -860,7 +860,7 @@ static int try_to_unmap_one(struct page
out_unmap:
pte_unmap_unlock(pte, ptl);

- if (MLOCK_PAGES && ret == SWAP_MLOCK) {
+ if (ret == SWAP_MLOCK) {
ret = SWAP_AGAIN;
if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
if (vma->vm_flags & VM_LOCKED) {
@@ -937,11 +937,10 @@ static int try_to_unmap_cluster(unsigned
return ret;

/*
- * MLOCK_PAGES => feature is configured.
- * if we can acquire the mmap_sem for read, and vma is VM_LOCKED,
+ * If we can acquire the mmap_sem for read, and vma is VM_LOCKED,
* keep the sem while scanning the cluster for mlocking pages.
*/
- if (MLOCK_PAGES && down_read_trylock(&vma->vm_mm->mmap_sem)) {
+ if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
locked_vma = (vma->vm_flags & VM_LOCKED);
if (!locked_vma)
up_read(&vma->vm_mm->mmap_sem); /* don't need it */
@@ -1065,14 +1064,11 @@ static int try_to_unmap_file(struct page
goto out;

/* We don't bother to try to find the munlocked page in nonlinears */
- if (MLOCK_PAGES && TTU_ACTION(flags) == TTU_MUNLOCK)
+ if (TTU_ACTION(flags) == TTU_MUNLOCK)
goto out;

list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
shared.vm_set.list) {
- if (!MLOCK_PAGES && !(flags & TTU_IGNORE_MLOCK) &&
- (vma->vm_flags & VM_LOCKED))
- continue;
cursor = (unsigned long) vma->vm_private_data;
if (cursor > max_nl_cursor)
max_nl_cursor = cursor;
@@ -1105,9 +1101,6 @@ static int try_to_unmap_file(struct page
do {
list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
shared.vm_set.list) {
- if (!MLOCK_PAGES && !(flags & TTU_IGNORE_MLOCK) &&
- (vma->vm_flags & VM_LOCKED))
- continue;
cursor = (unsigned long) vma->vm_private_data;
while ( cursor < max_nl_cursor &&
cursor < vma->vm_end - vma->vm_start) {