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authorHugh Dickins <hugh@veritas.com>2008-02-07 00:13:48 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-07 08:42:18 -0800
commit59bd26582de660d4c9c26125747f1b4a5eb40d1e (patch)
tree2b7606b3f18a87cdee5022381ba52f94efdb5d42 /mm/swapfile.c
parent1b6df3aa457690100f9827548943101447766572 (diff)
downloadlinux-59bd26582de660d4c9c26125747f1b4a5eb40d1e.tar.bz2
memcgroup: temporarily revert swapoff mod
This patch precisely reverts the "swapoff: scan ptes preemptibly" patch just presented. It's a temporary measure to allow existing memory controller patches to apply without rejects: in due course they should be rendered down into one sensible patch, and this reversion disappear. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/swapfile.c')
-rw-r--r--mm/swapfile.c38
1 files changed, 7 insertions, 31 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index eade24da9310..afae7b1f680b 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -506,19 +506,9 @@ unsigned int count_swap_pages(int type, int free)
* just let do_wp_page work it out if a write is requested later - to
* force COW, vm_page_prot omits write permission from any private vma.
*/
-static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
+static void unuse_pte(struct vm_area_struct *vma, pte_t *pte,
unsigned long addr, swp_entry_t entry, struct page *page)
{
- spinlock_t *ptl;
- pte_t *pte;
- int found = 1;
-
- pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
- if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) {
- found = 0;
- goto out;
- }
-
inc_mm_counter(vma->vm_mm, anon_rss);
get_page(page);
set_pte_at(vma->vm_mm, addr, pte,
@@ -530,9 +520,6 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
* immediately swapped out again after swapon.
*/
activate_page(page);
-out:
- pte_unmap_unlock(pte, ptl);
- return found;
}
static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
@@ -541,33 +528,22 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
{
pte_t swp_pte = swp_entry_to_pte(entry);
pte_t *pte;
+ spinlock_t *ptl;
int found = 0;
- /*
- * We don't actually need pte lock while scanning for swp_pte: since
- * we hold page lock and mmap_sem, swp_pte cannot be inserted into the
- * page table while we're scanning; though it could get zapped, and on
- * some architectures (e.g. x86_32 with PAE) we might catch a glimpse
- * of unmatched parts which look like swp_pte, so unuse_pte must
- * recheck under pte lock. Scanning without pte lock lets it be
- * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE.
- */
- pte = pte_offset_map(pmd, addr);
+ pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
do {
/*
* swapoff spends a _lot_ of time in this loop!
* Test inline before going to call unuse_pte.
*/
if (unlikely(pte_same(*pte, swp_pte))) {
- pte_unmap(pte);
- found = unuse_pte(vma, pmd, addr, entry, page);
- if (found)
- goto out;
- pte = pte_offset_map(pmd, addr);
+ unuse_pte(vma, pte++, addr, entry, page);
+ found = 1;
+ break;
}
} while (pte++, addr += PAGE_SIZE, addr != end);
- pte_unmap(pte - 1);
-out:
+ pte_unmap_unlock(pte - 1, ptl);
return found;
}