From: Wei Yang <richard.weiyang@gmail.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Wei Yang <richardw.yang@linux.intel.com>,
akpm@linux-foundation.org, kirill.shutemov@linux.intel.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] mm/page_vma_mapped: use PMD_SIZE instead of calculating it
Date: Thu, 28 Nov 2019 21:22:26 +0000 [thread overview]
Message-ID: <20191128212226.sfrhfs5m3q7m6tly@master> (raw)
In-Reply-To: <20191128083255.ab5rwj7gvktwunik@box.shutemov.name>
On Thu, Nov 28, 2019 at 11:32:55AM +0300, Kirill A. Shutemov wrote:
>On Thu, Nov 28, 2019 at 09:03:20AM +0800, Wei Yang wrote:
>> At this point, we are sure page is PageTransHuge, which means
>> hpage_nr_pages is HPAGE_PMD_NR.
>>
>> This is safe to use PMD_SIZE instead of calculating it.
>>
>> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
>> ---
>> mm/page_vma_mapped.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
>> index eff4b4520c8d..76e03650a3ab 100644
>> --- a/mm/page_vma_mapped.c
>> +++ b/mm/page_vma_mapped.c
>> @@ -223,7 +223,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
>> if (pvmw->address >= pvmw->vma->vm_end ||
>> pvmw->address >=
>> __vma_address(pvmw->page, pvmw->vma) +
>> - hpage_nr_pages(pvmw->page) * PAGE_SIZE)
>> + PMD_SIZE)
>> return not_found(pvmw);
>> /* Did we cross page table boundary? */
>> if (pvmw->address % PMD_SIZE == 0) {
>
>It is dubious cleanup. Maybe page_size(pvmw->page) instead? It will not
>break if we ever get PUD THP pages.
>
Thanks for your comment.
I took a look into the code again and found I may miss something.
I found we support PUD THP pages, whilc hpage_nr_pages() just return
HPAGE_PMD_NR on PageTransHuge. Why this is not possible to return PUD number?
Search in the kernel tree, one implementation of PUD_SIZE fault is
dev_dax_huge_fault. If page fault happens here, would this if break the loop
too early?
>--
> Kirill A. Shutemov
--
Wei Yang
Help you, Help me
next prev parent reply other threads:[~2019-11-28 21:22 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-28 1:03 Wei Yang
2019-11-28 1:03 ` [PATCH 2/2] mm/page_vma_mapped: page table boundary is already guaranteed Wei Yang
2019-11-28 8:31 ` Kirill A. Shutemov
2019-11-28 21:09 ` Wei Yang
2019-11-28 22:39 ` Matthew Wilcox
2019-11-29 8:30 ` Wei Yang
2019-11-29 11:18 ` Matthew Wilcox
2019-12-02 6:53 ` Wei Yang
2019-11-28 8:32 ` [PATCH 1/2] mm/page_vma_mapped: use PMD_SIZE instead of calculating it Kirill A. Shutemov
2019-11-28 21:22 ` Wei Yang [this message]
2019-12-02 8:03 ` Kirill A. Shutemov
2019-12-02 8:54 ` Wei Yang
2019-12-02 22:21 ` Wei Yang
2019-12-03 9:47 ` Kirill A. Shutemov
2019-12-03 15:14 ` Wei Yang
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