* [RFC patch] mm: hugetlb: fix __unmap_hugepage_range
@ 2014-10-31 4:22 Hillf Danton
2014-10-31 9:28 ` Michal Hocko
2014-11-03 23:36 ` David Rientjes
0 siblings, 2 replies; 3+ messages in thread
From: Hillf Danton @ 2014-10-31 4:22 UTC (permalink / raw)
To: 'Michal Hocko'
Cc: Andrew Morton, Hillf Danton, linux-kernel, linux-mm
First, after flushing TLB, we have no need to scan pte from start again.
Second, before bail out loop, the address is forwarded one step.
Signed-off-by: Hillf Danton <hillf.zj@alibaba-inc.com>
---
--- a/mm/hugetlb.c Fri Oct 31 11:47:25 2014
+++ b/mm/hugetlb.c Fri Oct 31 11:52:42 2014
@@ -2641,8 +2641,9 @@ void __unmap_hugepage_range(struct mmu_g
tlb_start_vma(tlb, vma);
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+ address = start;
again:
- for (address = start; address < end; address += sz) {
+ for (; address < end; address += sz) {
ptep = huge_pte_offset(mm, address);
if (!ptep)
continue;
@@ -2689,6 +2690,7 @@ again:
page_remove_rmap(page);
force_flush = !__tlb_remove_page(tlb, page);
if (force_flush) {
+ address += sz;
spin_unlock(ptl);
break;
}
--
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [RFC patch] mm: hugetlb: fix __unmap_hugepage_range
2014-10-31 4:22 [RFC patch] mm: hugetlb: fix __unmap_hugepage_range Hillf Danton
@ 2014-10-31 9:28 ` Michal Hocko
2014-11-03 23:36 ` David Rientjes
1 sibling, 0 replies; 3+ messages in thread
From: Michal Hocko @ 2014-10-31 9:28 UTC (permalink / raw)
To: Hillf Danton
Cc: Andrew Morton, linux-kernel, linux-mm, Aneesh Kumar K.V,
KAMEZAWA Hiroyuki
[CCing people involved in 24669e58477e2]
On Fri 31-10-14 12:22:12, Hillf Danton wrote:
> First, after flushing TLB, we have no need to scan pte from start again.
> Second, before bail out loop, the address is forwarded one step.
I can imagine a more comprehensive wording here. It is not immediately
clear whether this is just an optimization or a bug fix as well
(especially the second part).
Anyway the optimization looks good to me.
> Signed-off-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
> ---
>
> --- a/mm/hugetlb.c Fri Oct 31 11:47:25 2014
> +++ b/mm/hugetlb.c Fri Oct 31 11:52:42 2014
> @@ -2641,8 +2641,9 @@ void __unmap_hugepage_range(struct mmu_g
>
> tlb_start_vma(tlb, vma);
> mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
> + address = start;
> again:
> - for (address = start; address < end; address += sz) {
> + for (; address < end; address += sz) {
> ptep = huge_pte_offset(mm, address);
> if (!ptep)
> continue;
> @@ -2689,6 +2690,7 @@ again:
> page_remove_rmap(page);
> force_flush = !__tlb_remove_page(tlb, page);
> if (force_flush) {
> + address += sz;
> spin_unlock(ptl);
> break;
> }
> --
>
>
--
Michal Hocko
SUSE Labs
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [RFC patch] mm: hugetlb: fix __unmap_hugepage_range
2014-10-31 4:22 [RFC patch] mm: hugetlb: fix __unmap_hugepage_range Hillf Danton
2014-10-31 9:28 ` Michal Hocko
@ 2014-11-03 23:36 ` David Rientjes
1 sibling, 0 replies; 3+ messages in thread
From: David Rientjes @ 2014-11-03 23:36 UTC (permalink / raw)
To: Hillf Danton; +Cc: Michal Hocko, Andrew Morton, linux-kernel, linux-mm
On Fri, 31 Oct 2014, Hillf Danton wrote:
> First, after flushing TLB, we have no need to scan pte from start again.
> Second, before bail out loop, the address is forwarded one step.
>
> Signed-off-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: David Rientjes <rientjes@google.com>
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2014-10-31 4:22 [RFC patch] mm: hugetlb: fix __unmap_hugepage_range Hillf Danton
2014-10-31 9:28 ` Michal Hocko
2014-11-03 23:36 ` David Rientjes
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