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From: Catalin Marinas <catalin.marinas@arm.com>
To: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Will Deacon <will@kernel.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Muchun Song <muchun.song@linux.dev>,
	Mina Almasry <almasrymina@google.com>,
	kirill@shutemov.name, joel@joelfernandes.org,
	william.kucharski@oracle.com, kaleshsingh@google.com,
	linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] mm: mremap: use flush_pmd_tlb_range() in move_normal_pmd()
Date: Mon, 31 Jul 2023 12:05:25 +0100	[thread overview]
Message-ID: <ZMeVdcNcp76L8bOG@arm.com> (raw)
In-Reply-To: <20230731074829.79309-3-wangkefeng.wang@huawei.com>

On Mon, Jul 31, 2023 at 03:48:27PM +0800, Kefeng Wang wrote:
> Archs may need to do special things when flushing thp tlb,
> so use the more applicable flush_pud_tlb_range() instead of
> flush_tlb_range().
> 
> Fixes: 2c91bd4a4e2e ("mm: speed up mremap by 20x on large regions")
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>  mm/mremap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/mremap.c b/mm/mremap.c
> index 11e06e4ab33b..1883205fa22b 100644
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -284,7 +284,7 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
>  	VM_BUG_ON(!pmd_none(*new_pmd));
>  
>  	pmd_populate(mm, new_pmd, pmd_pgtable(pmd));
> -	flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
> +	flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE);

I don't think that's correct for arm64. The assumption in the
flush_p*d_tlb_range() was that they are called only for block mappings
at that p*d level (and we use FEAT_TTL on arm64 indicating that the leaf
level is level 2 for pmd, 1 for pud). IIUC move_normal_pmd() is only
called for table pmds which would have a leaf level of 3 (the pte).

Same for the next patch doing the equivalent for the pud.

-- 
Catalin

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WARNING: multiple messages have this Message-ID (diff)
From: Catalin Marinas <catalin.marinas@arm.com>
To: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Will Deacon <will@kernel.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Muchun Song <muchun.song@linux.dev>,
	Mina Almasry <almasrymina@google.com>,
	kirill@shutemov.name, joel@joelfernandes.org,
	william.kucharski@oracle.com, kaleshsingh@google.com,
	linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] mm: mremap: use flush_pmd_tlb_range() in move_normal_pmd()
Date: Mon, 31 Jul 2023 12:05:25 +0100	[thread overview]
Message-ID: <ZMeVdcNcp76L8bOG@arm.com> (raw)
In-Reply-To: <20230731074829.79309-3-wangkefeng.wang@huawei.com>

On Mon, Jul 31, 2023 at 03:48:27PM +0800, Kefeng Wang wrote:
> Archs may need to do special things when flushing thp tlb,
> so use the more applicable flush_pud_tlb_range() instead of
> flush_tlb_range().
> 
> Fixes: 2c91bd4a4e2e ("mm: speed up mremap by 20x on large regions")
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>  mm/mremap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/mremap.c b/mm/mremap.c
> index 11e06e4ab33b..1883205fa22b 100644
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -284,7 +284,7 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
>  	VM_BUG_ON(!pmd_none(*new_pmd));
>  
>  	pmd_populate(mm, new_pmd, pmd_pgtable(pmd));
> -	flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
> +	flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE);

I don't think that's correct for arm64. The assumption in the
flush_p*d_tlb_range() was that they are called only for block mappings
at that p*d level (and we use FEAT_TTL on arm64 indicating that the leaf
level is level 2 for pmd, 1 for pud). IIUC move_normal_pmd() is only
called for table pmds which would have a leaf level of 3 (the pte).

Same for the next patch doing the equivalent for the pud.

-- 
Catalin


  reply	other threads:[~2023-07-31 11:06 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-31  7:48 [PATCH 0/4] mm: mremap: fix move page tables Kefeng Wang
2023-07-31  7:48 ` Kefeng Wang
2023-07-31  7:48 ` [PATCH 1/4] mm: hugetlb: use flush_hugetlb_tlb_range() in move_hugetlb_page_tables() Kefeng Wang
2023-07-31  7:48   ` Kefeng Wang
2023-07-31 23:40   ` Mike Kravetz
2023-07-31 23:40     ` Mike Kravetz
2023-08-03  0:26     ` Mina Almasry
2023-08-03  0:26       ` Mina Almasry
2023-08-01  2:06   ` Muchun Song
2023-08-01  2:06     ` Muchun Song
2023-07-31  7:48 ` [PATCH 2/4] mm: mremap: use flush_pmd_tlb_range() in move_normal_pmd() Kefeng Wang
2023-07-31  7:48   ` Kefeng Wang
2023-07-31 11:05   ` Catalin Marinas [this message]
2023-07-31 11:05     ` Catalin Marinas
2023-07-31 11:20     ` Kefeng Wang
2023-07-31 11:20       ` Kefeng Wang
2023-07-31 13:58   ` kernel test robot
2023-07-31 13:58     ` kernel test robot
2023-07-31 21:43   ` kernel test robot
2023-07-31 21:43     ` kernel test robot
2023-07-31  7:48 ` [PATCH 3/4] mm: mremap: use flush_pud_tlb_range in move_normal_pud() Kefeng Wang
2023-07-31  7:48   ` Kefeng Wang
2023-07-31 16:42   ` kernel test robot
2023-07-31 16:42     ` kernel test robot
2023-07-31  7:48 ` [PATCH 4/4] arm64: tlb: set huge page size to stride for hugepage Kefeng Wang
2023-07-31  7:48   ` Kefeng Wang
2023-07-31  8:33   ` Barry Song
2023-07-31  8:33     ` Barry Song
2023-07-31  8:43     ` Barry Song
2023-07-31  8:43       ` Barry Song
2023-07-31  9:28       ` Kefeng Wang
2023-07-31  9:28         ` Kefeng Wang
2023-07-31 10:21         ` Barry Song
2023-07-31 10:21           ` Barry Song
2023-07-31 11:11   ` Catalin Marinas
2023-07-31 11:11     ` Catalin Marinas
2023-07-31 11:27     ` Kefeng Wang
2023-07-31 11:27       ` Kefeng Wang
2023-07-31 13:18       ` Catalin Marinas
2023-07-31 13:18         ` Catalin Marinas

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