linux-kernel - Re: [PATCH v12 33/69] powerpc: remove mmap linked list walks

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Message-ID: <230eb1be-180e-997e-ca51-c67cfa2dcb72@csgroup.eu>
Date:   Tue, 2 Aug 2022 10:36:26 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Liam Howlett <liam.howlett@...cle.com>,
        "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Hugh Dickins <hughd@...gle.com>
CC:     Yu Zhao <yuzhao@...gle.com>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH v12 33/69] powerpc: remove mmap linked list walks



Le 20/07/2022 à 04:17, Liam Howlett a écrit :
> From: "Matthew Wilcox (Oracle)" <willy@...radead.org>
> 
> Use the VMA iterator instead.

Can you please copy powerpc maintainers/reviewers when sending such a 
patch ?

Thanks
Christophe

> 
> Link: https://lkml.kernel.org/r/20220504011345.662299-18-Liam.Howlett@oracle.com
> Link: https://lkml.kernel.org/r/20220621204632.3370049-34-Liam.Howlett@oracle.com
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: David Howells <dhowells@...hat.com>
> Cc: SeongJae Park <sj@...nel.org>
> Cc: Will Deacon <will@...nel.org>
> Cc: Davidlohr Bueso <dave@...olabs.net>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> ---
>   arch/powerpc/kernel/vdso.c              |  6 +++---
>   arch/powerpc/mm/book3s32/tlb.c          | 11 ++++++-----
>   arch/powerpc/mm/book3s64/subpage_prot.c | 13 ++-----------
>   3 files changed, 11 insertions(+), 19 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
> index 0da287544054..94a8fa5017c3 100644
> --- a/arch/powerpc/kernel/vdso.c
> +++ b/arch/powerpc/kernel/vdso.c
> @@ -113,18 +113,18 @@ struct vdso_data *arch_get_vdso_data(void *vvar_page)
>   int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
>   {
>   	struct mm_struct *mm = task->mm;
> +	VMA_ITERATOR(vmi, mm, 0);
>   	struct vm_area_struct *vma;
>   
>   	mmap_read_lock(mm);
> -
> -	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> +	for_each_vma(vmi, vma) {
>   		unsigned long size = vma->vm_end - vma->vm_start;
>   
>   		if (vma_is_special_mapping(vma, &vvar_spec))
>   			zap_page_range(vma, vma->vm_start, size);
>   	}
> -
>   	mmap_read_unlock(mm);
> +
>   	return 0;
>   }
>   
> diff --git a/arch/powerpc/mm/book3s32/tlb.c b/arch/powerpc/mm/book3s32/tlb.c
> index 19f0ef950d77..9ad6b56bfec9 100644
> --- a/arch/powerpc/mm/book3s32/tlb.c
> +++ b/arch/powerpc/mm/book3s32/tlb.c
> @@ -81,14 +81,15 @@ EXPORT_SYMBOL(hash__flush_range);
>   void hash__flush_tlb_mm(struct mm_struct *mm)
>   {
>   	struct vm_area_struct *mp;
> +	VMA_ITERATOR(vmi, mm, 0);
>   
>   	/*
> -	 * It is safe to go down the mm's list of vmas when called
> -	 * from dup_mmap, holding mmap_lock.  It would also be safe from
> -	 * unmap_region or exit_mmap, but not from vmtruncate on SMP -
> -	 * but it seems dup_mmap is the only SMP case which gets here.
> +	 * It is safe to iterate the vmas when called from dup_mmap,
> +	 * holding mmap_lock.  It would also be safe from unmap_region
> +	 * or exit_mmap, but not from vmtruncate on SMP - but it seems
> +	 * dup_mmap is the only SMP case which gets here.
>   	 */
> -	for (mp = mm->mmap; mp != NULL; mp = mp->vm_next)
> +	for_each_vma(vmi, mp)
>   		hash__flush_range(mp->vm_mm, mp->vm_start, mp->vm_end);
>   }
>   EXPORT_SYMBOL(hash__flush_tlb_mm);
> diff --git a/arch/powerpc/mm/book3s64/subpage_prot.c b/arch/powerpc/mm/book3s64/subpage_prot.c
> index 60c6ea16a972..d73b3b4176e8 100644
> --- a/arch/powerpc/mm/book3s64/subpage_prot.c
> +++ b/arch/powerpc/mm/book3s64/subpage_prot.c
> @@ -149,24 +149,15 @@ static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,
>   				    unsigned long len)
>   {
>   	struct vm_area_struct *vma;
> +	VMA_ITERATOR(vmi, mm, addr);
>   
>   	/*
>   	 * We don't try too hard, we just mark all the vma in that range
>   	 * VM_NOHUGEPAGE and split them.
>   	 */
> -	vma = find_vma(mm, addr);
> -	/*
> -	 * If the range is in unmapped range, just return
> -	 */
> -	if (vma && ((addr + len) <= vma->vm_start))
> -		return;
> -
> -	while (vma) {
> -		if (vma->vm_start >= (addr + len))
> -			break;
> +	for_each_vma_range(vmi, vma, addr + len) {
>   		vma->vm_flags |= VM_NOHUGEPAGE;
>   		walk_page_vma(vma, &subpage_walk_ops, NULL);
> -		vma = vma->vm_next;
>   	}
>   }
>   #else