* [PATCH] mm/hugetlb: Remove redundant VM_BUG_ON_PAGE on putback_active_hugepage()
@ 2021-02-08 8:37 Miaohe Lin
2021-02-09 1:26 ` Mike Kravetz
0 siblings, 1 reply; 5+ messages in thread
From: Miaohe Lin @ 2021-02-08 8:37 UTC (permalink / raw)
To: akpm, mike.kravetz; +Cc: linux-mm, linux-kernel, linmiaohe
PageHead(page) is implicitly checked in set_page_huge_active() via the
PageHeadHuge(page) check. So remove this explicit one.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
mm/hugetlb.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 6cdb59d8f663..bbbe013a3a2d 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5577,7 +5577,6 @@ bool isolate_huge_page(struct page *page, struct list_head *list)
void putback_active_hugepage(struct page *page)
{
- VM_BUG_ON_PAGE(!PageHead(page), page);
spin_lock(&hugetlb_lock);
SetHPageMigratable(page);
list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
--
2.19.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] mm/hugetlb: Remove redundant VM_BUG_ON_PAGE on putback_active_hugepage()
2021-02-08 8:37 [PATCH] mm/hugetlb: Remove redundant VM_BUG_ON_PAGE on putback_active_hugepage() Miaohe Lin
@ 2021-02-09 1:26 ` Mike Kravetz
2021-02-09 2:10 ` Miaohe Lin
0 siblings, 1 reply; 5+ messages in thread
From: Mike Kravetz @ 2021-02-09 1:26 UTC (permalink / raw)
To: Miaohe Lin, akpm; +Cc: linux-mm, linux-kernel
On 2/8/21 12:37 AM, Miaohe Lin wrote:
> PageHead(page) is implicitly checked in set_page_huge_active() via the
> PageHeadHuge(page) check. So remove this explicit one.
I do not disagree with the code change. However, this commit message
is not accurate. set_page_huge_active() no longer exists in the tree
you are changing. It was replaced with SetHPageMigratable. Also, the
VM_BUG_ON_PAGE(!PageHeadHuge(page), page) was removed in the process.
So, there is no redundant check.
However, a quick audit of calling code reveals that all callers know they
are operating on a hugetlb head page.
--
Mike Kravetz
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> mm/hugetlb.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 6cdb59d8f663..bbbe013a3a2d 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -5577,7 +5577,6 @@ bool isolate_huge_page(struct page *page, struct list_head *list)
>
> void putback_active_hugepage(struct page *page)
> {
> - VM_BUG_ON_PAGE(!PageHead(page), page);
> spin_lock(&hugetlb_lock);
> SetHPageMigratable(page);
> list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm/hugetlb: Remove redundant VM_BUG_ON_PAGE on putback_active_hugepage()
2021-02-09 1:26 ` Mike Kravetz
@ 2021-02-09 2:10 ` Miaohe Lin
2021-02-09 3:39 ` Mike Kravetz
0 siblings, 1 reply; 5+ messages in thread
From: Miaohe Lin @ 2021-02-09 2:10 UTC (permalink / raw)
To: Mike Kravetz, akpm; +Cc: linux-mm, linux-kernel
Hi:
On 2021/2/9 9:26, Mike Kravetz wrote:
> On 2/8/21 12:37 AM, Miaohe Lin wrote:
>> PageHead(page) is implicitly checked in set_page_huge_active() via the
>> PageHeadHuge(page) check. So remove this explicit one.
>
> I do not disagree with the code change. However, this commit message
> is not accurate. set_page_huge_active() no longer exists in the tree
> you are changing. It was replaced with SetHPageMigratable. Also, the
> VM_BUG_ON_PAGE(!PageHeadHuge(page), page) was removed in the process.
> So, there is no redundant check.
>
> However, a quick audit of calling code reveals that all callers know they
> are operating on a hugetlb head page.
>
So I should change the commit log like:
All callers know they are operating on a hugetlb head page. So this VM_BUG_ON_PAGE
can't catch anything useful.
and send a v2. Right?
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm/hugetlb: Remove redundant VM_BUG_ON_PAGE on putback_active_hugepage()
2021-02-09 2:10 ` Miaohe Lin
@ 2021-02-09 3:39 ` Mike Kravetz
2021-02-09 6:19 ` Miaohe Lin
0 siblings, 1 reply; 5+ messages in thread
From: Mike Kravetz @ 2021-02-09 3:39 UTC (permalink / raw)
To: Miaohe Lin, akpm; +Cc: linux-mm, linux-kernel
On 2/8/21 6:10 PM, Miaohe Lin wrote:
> Hi:
> On 2021/2/9 9:26, Mike Kravetz wrote:
>> On 2/8/21 12:37 AM, Miaohe Lin wrote:
>>> PageHead(page) is implicitly checked in set_page_huge_active() via the
>>> PageHeadHuge(page) check. So remove this explicit one.
>>
>> I do not disagree with the code change. However, this commit message
>> is not accurate. set_page_huge_active() no longer exists in the tree
>> you are changing. It was replaced with SetHPageMigratable. Also, the
>> VM_BUG_ON_PAGE(!PageHeadHuge(page), page) was removed in the process.
>> So, there is no redundant check.
>>
>> However, a quick audit of calling code reveals that all callers know they
>> are operating on a hugetlb head page.
>>
>
> So I should change the commit log like:
>
> All callers know they are operating on a hugetlb head page. So this VM_BUG_ON_PAGE
> can't catch anything useful.
>
> and send a v2. Right?
Correct,
--
Mike Kravetz
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm/hugetlb: Remove redundant VM_BUG_ON_PAGE on putback_active_hugepage()
2021-02-09 3:39 ` Mike Kravetz
@ 2021-02-09 6:19 ` Miaohe Lin
0 siblings, 0 replies; 5+ messages in thread
From: Miaohe Lin @ 2021-02-09 6:19 UTC (permalink / raw)
To: Mike Kravetz, akpm; +Cc: linux-mm, linux-kernel
Hi:
On 2021/2/9 11:39, Mike Kravetz wrote:
> On 2/8/21 6:10 PM, Miaohe Lin wrote:
>> Hi:
>> On 2021/2/9 9:26, Mike Kravetz wrote:
>>> On 2/8/21 12:37 AM, Miaohe Lin wrote:
>>>> PageHead(page) is implicitly checked in set_page_huge_active() via the
>>>> PageHeadHuge(page) check. So remove this explicit one.
>>>
>>> I do not disagree with the code change. However, this commit message
>>> is not accurate. set_page_huge_active() no longer exists in the tree
>>> you are changing. It was replaced with SetHPageMigratable. Also, the
>>> VM_BUG_ON_PAGE(!PageHeadHuge(page), page) was removed in the process.
>>> So, there is no redundant check.
>>>
>>> However, a quick audit of calling code reveals that all callers know they
>>> are operating on a hugetlb head page.
>>>
>>
>> So I should change the commit log like:
>>
>> All callers know they are operating on a hugetlb head page. So this VM_BUG_ON_PAGE
>> can't catch anything useful.
>>
>> and send a v2. Right?
>
> Correct,
>
Will do. Thanks a lot.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-02-09 6:19 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2021-02-08 8:37 [PATCH] mm/hugetlb: Remove redundant VM_BUG_ON_PAGE on putback_active_hugepage() Miaohe Lin
2021-02-09 1:26 ` Mike Kravetz
2021-02-09 2:10 ` Miaohe Lin
2021-02-09 3:39 ` Mike Kravetz
2021-02-09 6:19 ` Miaohe Lin
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