linux-kernel - Re: [PATCH] mips: fix HUGETLB function without THP enabled

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Date:   Tue, 2 Nov 2021 20:17:52 +0800 (CST)
From:   "Zhaolong Zhang" <zhangzl2013@....com>
To:     "Thomas Bogendoerfer" <tsbogend@...ha.franken.de>
Cc:     "Alexander Lobakin" <alobakin@...me>,
        "Yanteng Si" <siyanteng@...ngson.cn>, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mips: fix HUGETLB function without THP enabled


At 2021-11-02 18:20:51, "Thomas Bogendoerfer" <tsbogend@...ha.franken.de> wrote:
>On Tue, Nov 02, 2021 at 04:24:37PM +0800, Zhaolong Zhang wrote:
>> ltp test futex_wake04 without THP enabled leads to below bt:
>>   [<ffffffff80a03728>] BUG+0x0/0x8
>>   [<ffffffff80a0624c>] internal_get_user_pages_fast+0x81c/0x820
>>   [<ffffffff8093ac18>] get_futex_key+0xa0/0x480
>>   [<ffffffff8093b074>] futex_wait_setup+0x7c/0x1a8
>>   [<ffffffff8093b2c0>] futex_wait+0x120/0x228
>>   [<ffffffff8093dbe8>] do_futex+0x140/0xbd8
>>   [<ffffffff8093e78c>] sys_futex+0x10c/0x1c0
>>   [<ffffffff808703d0>] syscall_common+0x34/0x58
>> 
>> Move pmd_write() and pmd_page() from TRANSPARENT_HUGEPAGE scope to
>> MIPS_HUGE_TLB_SUPPORT scope, because both THP and HUGETLB will need
>> them.
>> 
>> Signed-off-by: Zhaolong Zhang <zhangzl2013@....com>
>> ---
>>  arch/mips/include/asm/pgtable.h | 40 +++++++++++++++++----------------
>>  1 file changed, 21 insertions(+), 19 deletions(-)
>
>applied to mips-next.
>
>> 
>> diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
>> index 804889b70965..1fcf4be5cd20 100644
>> --- a/arch/mips/include/asm/pgtable.h
>> +++ b/arch/mips/include/asm/pgtable.h
>> @@ -86,10 +86,12 @@ extern void paging_init(void);
>>   */
>>  #define pmd_phys(pmd)		virt_to_phys((void *)pmd_val(pmd))
>>  
>> +#ifndef CONFIG_MIPS_HUGE_TLB_SUPPORT
>>  #define __pmd_page(pmd)		(pfn_to_page(pmd_phys(pmd) >> PAGE_SHIFT))
>>  #ifndef CONFIG_TRANSPARENT_HUGEPAGE
>>  #define pmd_page(pmd)		__pmd_page(pmd)
>>  #endif /* CONFIG_TRANSPARENT_HUGEPAGE  */
>> +#endif /* CONFIG_MIPS_HUGE_TLB_SUPPORT */
>
>While applying I've simplified that hunk to
>
>-#define __pmd_page(pmd)                (pfn_to_page(pmd_phys(pmd) >> PAGE_SHIFT))
>-#ifndef CONFIG_TRANSPARENT_HUGEPAGE
>-#define pmd_page(pmd)          __pmd_page(pmd)
>-#endif /* CONFIG_TRANSPARENT_HUGEPAGE  */
>+#ifndef CONFIG_MIPS_HUGE_TLB_SUPPORT
>+#define pmd_page(pmd)          (pfn_to_page(pmd_phys(pmd) >> PAGE_SHIFT))
>+#endif /* CONFIG_MIPS_HUGE_TLB_SUPPORT */
>

It is much better.
Thanks for your kind reply.

Regards,
Zhaolong

>Thomas.
>
>-- 
>Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
>good idea.                                                [ RFC1925, 2.3 ]