On Mon, Jul 13, 2015 at 09:23:41AM -0400, Jeff Moyer wrote:
> Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx> writes:
>
> > +static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
> > + pmd_t *pmd, unsigned long pfn, pgprot_t prot, bool write)
> > +{
> > + return VM_FAULT_NOPAGE;
> > +}
>
> What's the point of the return value?
Good point. Originally, it paralleled insert_pfn() in mm/memory.c, but it
became apparent that the return code of 0 or -Exxx was useless, and in converting insert_pfn_pmd over to VM_FAULT_ codes, all possible return codes were
going to be VM_FAULT_NOPAGE. It didn't occur to me to take it one step further and make the function return void.
It doesn't make much difference either way:
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 26d0fc1..5ffdcaa 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -837,7 +837,7 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
return 0;
}
-static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
+static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
pmd_t *pmd, unsigned long pfn, pgprot_t prot, bool write)
{
struct mm_struct *mm = vma->vm_mm;
@@ -855,7 +855,6 @@ static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
update_mmu_cache_pmd(vma, addr, pmd);
}
spin_unlock(ptl);
- return VM_FAULT_NOPAGE;
}
int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
@@ -877,7 +876,8 @@ int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
return VM_FAULT_SIGBUS;
if (track_pfn_insert(vma, &pgprot, pfn))
return VM_FAULT_SIGBUS;
- return insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write);
+ insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write);
+ return VM_FAULT_NOPAGE;
}
int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
I suppose it's slightly cleaner. I'll integrate this for the next release.
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