diff options
| author | Dave Hansen <dave@linux.vnet.ibm.com> | 2011-03-22 16:32:56 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-03-22 17:44:04 -0700 |
| commit | 033193275b3ffcfe7f3fde7b569f3d207f6cd6a0 (patch) | |
| tree | fc65fa02248f855f0f63e087f35a507b6abb5617 /mm/memcontrol.c | |
| parent | 278df9f451dc71dcd002246be48358a473504ad0 (diff) | |
pagewalk: only split huge pages when necessary
Right now, if a mm_walk has either ->pte_entry or ->pmd_entry set, it will
unconditionally split any transparent huge pages it runs in to. In
practice, that means that anyone doing a
cat /proc/$pid/smaps
will unconditionally break down every huge page in the process and depend
on khugepaged to re-collapse it later. This is fairly suboptimal.
This patch changes that behavior. It teaches each ->pmd_entry handler
(there are five) that they must break down the THPs themselves. Also, the
_generic_ code will never break down a THP unless a ->pte_entry handler is
actually set.
This means that the ->pmd_entry handlers can now choose to deal with THPs
without breaking them down.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Eric B Munson <emunson@mgebm.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Cc: Michael J Wolf <mjwolf@us.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 9e0f05efd114..e1ee6ad9c971 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4763,7 +4763,8 @@ static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd, pte_t *pte; spinlock_t *ptl; - VM_BUG_ON(pmd_trans_huge(*pmd)); + split_huge_page_pmd(walk->mm, pmd); + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); for (; addr != end; pte++, addr += PAGE_SIZE) if (is_target_pte_for_mc(vma, addr, *pte, NULL)) @@ -4925,8 +4926,8 @@ static int mem_cgroup_move_charge_pte_range(pmd_t *pmd, pte_t *pte; spinlock_t *ptl; + split_huge_page_pmd(walk->mm, pmd); retry: - VM_BUG_ON(pmd_trans_huge(*pmd)); pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); for (; addr != end; addr += PAGE_SIZE) { pte_t ptent = *(pte++); |