From: zhongjiang@huawei•com (zhong jiang)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC] mm: Do not look up the next level table when large page exist.
Date: Thu, 26 Jul 2018 09:51:30 +0800 [thread overview]
Message-ID: <5B592922.1030204@huawei.com> (raw)
In-Reply-To: <20180725165334.4zjsenp6p3cdureq@armageddon.cambridge.arm.com>
On 2018/7/26 0:53, Catalin Marinas wrote:
> On Wed, Jul 25, 2018 at 11:21:59PM +0800, zhong jiang wrote:
>> show_pte can show the kernel page table and user page table. user
>> page table is totally four level table.
> Well, you can have huge pages in user space.
No, I have not.
>> but kernel page table can
>> be a large page. Therefore, it need to check the page table.
>>
>> Signed-off-by: zhong jiang <zhongjiang@huawei•com>
>> ---
>> arch/arm64/mm/fault.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
>> index 1b40676..a397a54 100644
>> --- a/arch/arm64/mm/fault.c
>> +++ b/arch/arm64/mm/fault.c
>> @@ -169,13 +169,13 @@ void show_pte(unsigned long addr)
>> pudp = pud_offset(pgdp, addr);
>> pud = READ_ONCE(*pudp);
>> pr_cont(", pud=%016llx", pud_val(pud));
>> - if (pud_none(pud) || pud_bad(pud))
>> + if (pud_none(pud) || pud_bad(pud) || pud_sect(pud))
> Have you actually hit a problem with this code?
Not yet. Maybe I use the function mistake. It is only used for user and vmalloc
pagefault. It should be not handled with large level table. thank you for time.
Thanks,
zhong jiang
> pud_sect() checks that the bottom two bits of the pud are 0b01.
> pud_bad() is true when bit 1 is 0, which is the case with a section
> mapping.
>
prev parent reply other threads:[~2018-07-26 1:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-25 15:21 [RFC] mm: Do not look up the next level table when large page exist zhong jiang
2018-07-25 16:53 ` Catalin Marinas
2018-07-26 1:51 ` zhong jiang [this message]
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