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mm: huge_memory: use GFP_TRANSHUGE when charging huge pages 

Transparent huge page charges prefer falling back to regular pages
rather than spending a lot of time in direct reclaim.

Desired reclaim behavior is usually declared in the gfp mask, but THP
charges use GFP_KERNEL and then rely on the fact that OOM is disabled
for THP charges, and that OOM-disabled charges don't retry reclaim.
Needless to say, this is anything but obvious and quite error prone.

Convert THP charges to use GFP_TRANSHUGE instead, which implies
__GFP_NORETRY, to indicate the low-latency requirement.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner 2014-08-06 16:05:49 -07:00 committed by Linus Torvalds
parent 28c34c291e
commit d51d885bbb
1 changed files with 3 additions and 3 deletions
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6
mm/huge_memory.c
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@ -827,7 +827,7 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
count_vm_event(THP_FAULT_FALLBACK);
return VM_FAULT_FALLBACK;
}
if (unlikely(mem_cgroup_charge_anon(page, mm, GFP_KERNEL))) {
if (unlikely(mem_cgroup_charge_anon(page, mm, GFP_TRANSHUGE))) {
put_page(page);
count_vm_event(THP_FAULT_FALLBACK);
return VM_FAULT_FALLBACK;
@ -1132,7 +1132,7 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
goto out;
}
if (unlikely(mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL))) {
if (unlikely(mem_cgroup_charge_anon(new_page, mm, GFP_TRANSHUGE))) {
put_page(new_page);
if (page) {
split_huge_page(page);
@ -2399,7 +2399,7 @@ static void collapse_huge_page(struct mm_struct *mm,
if (!new_page)
return;
if (unlikely(mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)))
if (unlikely(mem_cgroup_charge_anon(new_page, mm, GFP_TRANSHUGE)))
return;
/*