Re: [PATCH v3 6/6] mm/hugetlb: remove unused argument of follow_huge_addr()

[Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>]

On Wed, Sep 03, 2014 at 02:26:37PM -0700, Hugh Dickins wrote:
> On Thu, 28 Aug 2014, Naoya Horiguchi wrote:
> 
> > follow_huge_addr()'s parameter write is not used, so let's remove it.
> > 
> > Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> 
> I think this patch is a waste of time: that it should be replaced
> by a patch which replaces the "write" argument by a "flags" argument,

OK, I just drop this patch.

> so that follow_huge_addr() can do get_page() for FOLL_GET while holding
> appropriate lock, instead of the BUG_ON(flags & FOLL_GET) we currently
> have.
> 
> Once that is implemented, you could try getting hugetlb migration
> tested on ia64 and powerpc; but yes, keep hugetlb migration disabled
> on all but x86 until it has been tested elsewhere.
> 
> > ---
> >  arch/ia64/mm/hugetlbpage.c    | 2 +-
> >  arch/powerpc/mm/hugetlbpage.c | 2 +-
> >  arch/x86/mm/hugetlbpage.c     | 2 +-
> >  include/linux/hugetlb.h       | 5 ++---
> >  mm/gup.c                      | 2 +-
> >  mm/hugetlb.c                  | 3 +--
> >  6 files changed, 7 insertions(+), 9 deletions(-)
> > 
> > diff --git mmotm-2014-08-25-16-52.orig/arch/ia64/mm/hugetlbpage.c mmotm-2014-08-25-16-52/arch/ia64/mm/hugetlbpage.c
> > index 6170381bf074..524a4e001bda 100644
> > --- mmotm-2014-08-25-16-52.orig/arch/ia64/mm/hugetlbpage.c
> > +++ mmotm-2014-08-25-16-52/arch/ia64/mm/hugetlbpage.c
> > @@ -89,7 +89,7 @@ int prepare_hugepage_range(struct file *file,
> >  	return 0;
> >  }
> >  
> > -struct page *follow_huge_addr(struct mm_struct *mm, unsigned long addr, int write)
> > +struct page *follow_huge_addr(struct mm_struct *mm, unsigned long addr)
> >  {
> >  	struct page *page = NULL;
> >  	pte_t *ptep;
> > diff --git mmotm-2014-08-25-16-52.orig/arch/powerpc/mm/hugetlbpage.c mmotm-2014-08-25-16-52/arch/powerpc/mm/hugetlbpage.c
> > index 1d8854a56309..5b6fe8b0cde3 100644
> > --- mmotm-2014-08-25-16-52.orig/arch/powerpc/mm/hugetlbpage.c
> > +++ mmotm-2014-08-25-16-52/arch/powerpc/mm/hugetlbpage.c
> > @@ -674,7 +674,7 @@ void hugetlb_free_pgd_range(struct mmu_gather *tlb,
> >  }
> >  
> >  struct page *
> > -follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
> > +follow_huge_addr(struct mm_struct *mm, unsigned long address)
> >  {
> >  	pte_t *ptep;
> >  	struct page *page = ERR_PTR(-EINVAL);
> > diff --git mmotm-2014-08-25-16-52.orig/arch/x86/mm/hugetlbpage.c mmotm-2014-08-25-16-52/arch/x86/mm/hugetlbpage.c
> > index 03b8a7c11817..cab09d87ae65 100644
> > --- mmotm-2014-08-25-16-52.orig/arch/x86/mm/hugetlbpage.c
> > +++ mmotm-2014-08-25-16-52/arch/x86/mm/hugetlbpage.c
> > @@ -18,7 +18,7 @@
> >  
> >  #if 0	/* This is just for testing */
> >  struct page *
> > -follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
> > +follow_huge_addr(struct mm_struct *mm, unsigned long address)
> >  {
> >  	unsigned long start = address;
> >  	int length = 1;
> > diff --git mmotm-2014-08-25-16-52.orig/include/linux/hugetlb.h mmotm-2014-08-25-16-52/include/linux/hugetlb.h
> > index b3200fce07aa..cdff1bd393bb 100644
> > --- mmotm-2014-08-25-16-52.orig/include/linux/hugetlb.h
> > +++ mmotm-2014-08-25-16-52/include/linux/hugetlb.h
> > @@ -96,8 +96,7 @@ pte_t *huge_pte_alloc(struct mm_struct *mm,
> >  			unsigned long addr, unsigned long sz);
> >  pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr);
> >  int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep);
> > -struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
> > -			      int write);
> > +struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address);
> >  struct page *follow_huge_pmd(struct vm_area_struct *vma, unsigned long address,
> >  				pmd_t *pmd, int flags);
> >  struct page *follow_huge_pud(struct vm_area_struct *vma, unsigned long address,
> > @@ -124,7 +123,7 @@ static inline unsigned long hugetlb_total_pages(void)
> >  }
> >  
> >  #define follow_hugetlb_page(m,v,p,vs,a,b,i,w)	({ BUG(); 0; })
> > -#define follow_huge_addr(mm, addr, write)	ERR_PTR(-EINVAL)
> > +#define follow_huge_addr(mm, addr)	ERR_PTR(-EINVAL)
> >  #define copy_hugetlb_page_range(src, dst, vma)	({ BUG(); 0; })
> >  static inline void hugetlb_report_meminfo(struct seq_file *m)
> >  {
> > diff --git mmotm-2014-08-25-16-52.orig/mm/gup.c mmotm-2014-08-25-16-52/mm/gup.c
> > index 597a5e92e265..8f0550f1770d 100644
> > --- mmotm-2014-08-25-16-52.orig/mm/gup.c
> > +++ mmotm-2014-08-25-16-52/mm/gup.c
> > @@ -149,7 +149,7 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
> >  
> >  	*page_mask = 0;
> >  
> > -	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
> > +	page = follow_huge_addr(mm, address);
> >  	if (!IS_ERR(page)) {
> >  		BUG_ON(flags & FOLL_GET);
> >  		return page;
> > diff --git mmotm-2014-08-25-16-52.orig/mm/hugetlb.c mmotm-2014-08-25-16-52/mm/hugetlb.c
> > index 0a4511115ee0..f7dcad3474ec 100644
> > --- mmotm-2014-08-25-16-52.orig/mm/hugetlb.c
> > +++ mmotm-2014-08-25-16-52/mm/hugetlb.c
> > @@ -3690,8 +3690,7 @@ pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
> >   * behavior.
> >   */
> >  struct page * __weak
> > -follow_huge_addr(struct mm_struct *mm, unsigned long address,
> > -			      int write)
> > +follow_huge_addr(struct mm_struct *mm, unsigned long address)
> >  {
> >  	return ERR_PTR(-EINVAL);
> >  }
> > -- 
> > 1.9.3
> 

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