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Message-ID: <20140723091040.GC15688@quack.suse.cz>
Date: Wed, 23 Jul 2014 11:10:40 +0200
From: Jan Kara <jack@...e.cz>
To: Matthew Wilcox <matthew.r.wilcox@...el.com>
Cc: linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
Matthew Wilcox <willy@...ux.intel.com>
Subject: Re: [PATCH v8 05/22] Add vm_replace_mixed()
On Tue 22-07-14 15:47:53, Matthew Wilcox wrote:
> From: Matthew Wilcox <willy@...ux.intel.com>
>
> vm_insert_mixed() will fail if there is already a valid PTE at that
> location. The DAX code would rather replace the previous value with
> the new PTE.
>
> Signed-off-by: Matthew Wilcox <willy@...ux.intel.com>
This looks good to me although I'm not an expert in this area. So just:
Acked-by: Jan Kara <jack@...e.cz>
Honza
> ---
> include/linux/mm.h | 8 ++++++--
> mm/memory.c | 34 +++++++++++++++++++++-------------
> 2 files changed, 27 insertions(+), 15 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index e04f531..8d1194c 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1958,8 +1958,12 @@ int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
> int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);
> int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
> unsigned long pfn);
> -int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
> - unsigned long pfn);
> +int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
> + unsigned long pfn, bool replace);
> +#define vm_insert_mixed(vma, addr, pfn) \
> + __vm_insert_mixed(vma, addr, pfn, false)
> +#define vm_replace_mixed(vma, addr, pfn) \
> + __vm_insert_mixed(vma, addr, pfn, true)
> int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
>
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 42bf429..cf06c97 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1476,7 +1476,7 @@ pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
> * pages reserved for the old functions anyway.
> */
> static int insert_page(struct vm_area_struct *vma, unsigned long addr,
> - struct page *page, pgprot_t prot)
> + struct page *page, pgprot_t prot, bool replace)
> {
> struct mm_struct *mm = vma->vm_mm;
> int retval;
> @@ -1492,8 +1492,12 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,
> if (!pte)
> goto out;
> retval = -EBUSY;
> - if (!pte_none(*pte))
> - goto out_unlock;
> + if (!pte_none(*pte)) {
> + if (!replace)
> + goto out_unlock;
> + VM_BUG_ON(!mutex_is_locked(&vma->vm_file->f_mapping->i_mmap_mutex));
> + zap_page_range_single(vma, addr, PAGE_SIZE, NULL);
> + }
>
> /* Ok, finally just insert the thing.. */
> get_page(page);
> @@ -1549,12 +1553,12 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
> BUG_ON(vma->vm_flags & VM_PFNMAP);
> vma->vm_flags |= VM_MIXEDMAP;
> }
> - return insert_page(vma, addr, page, vma->vm_page_prot);
> + return insert_page(vma, addr, page, vma->vm_page_prot, false);
> }
> EXPORT_SYMBOL(vm_insert_page);
>
> static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
> - unsigned long pfn, pgprot_t prot)
> + unsigned long pfn, pgprot_t prot, bool replace)
> {
> struct mm_struct *mm = vma->vm_mm;
> int retval;
> @@ -1566,8 +1570,12 @@ static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
> if (!pte)
> goto out;
> retval = -EBUSY;
> - if (!pte_none(*pte))
> - goto out_unlock;
> + if (!pte_none(*pte)) {
> + if (!replace)
> + goto out_unlock;
> + VM_BUG_ON(!mutex_is_locked(&vma->vm_file->f_mapping->i_mmap_mutex));
> + zap_page_range_single(vma, addr, PAGE_SIZE, NULL);
> + }
>
> /* Ok, finally just insert the thing.. */
> entry = pte_mkspecial(pfn_pte(pfn, prot));
> @@ -1620,14 +1628,14 @@ int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
> if (track_pfn_insert(vma, &pgprot, pfn))
> return -EINVAL;
>
> - ret = insert_pfn(vma, addr, pfn, pgprot);
> + ret = insert_pfn(vma, addr, pfn, pgprot, false);
>
> return ret;
> }
> EXPORT_SYMBOL(vm_insert_pfn);
>
> -int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
> - unsigned long pfn)
> +int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
> + unsigned long pfn, bool replace)
> {
> BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
>
> @@ -1645,11 +1653,11 @@ int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
> struct page *page;
>
> page = pfn_to_page(pfn);
> - return insert_page(vma, addr, page, vma->vm_page_prot);
> + return insert_page(vma, addr, page, vma->vm_page_prot, replace);
> }
> - return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
> + return insert_pfn(vma, addr, pfn, vma->vm_page_prot, replace);
> }
> -EXPORT_SYMBOL(vm_insert_mixed);
> +EXPORT_SYMBOL(__vm_insert_mixed);
>
> /*
> * maps a range of physical memory into the requested pages. the old
> --
> 2.0.0
>
> --
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--
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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