The return value from set_huge_zero_page() is never checked so simplify
the code by making it return void.
Signed-off-by: Ralph Campbell <[email protected]>
---
mm/huge_memory.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c5cb6dcd6c69..6cf0ee65538d 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -686,20 +686,18 @@ static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
}
/* Caller must hold page table lock. */
-static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
+static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
struct page *zero_page)
{
pmd_t entry;
- if (!pmd_none(*pmd))
- return false;
+
entry = mk_pmd(zero_page, vma->vm_page_prot);
entry = pmd_mkhuge(entry);
if (pgtable)
pgtable_trans_huge_deposit(mm, pmd, pgtable);
set_pmd_at(mm, haddr, pmd, entry);
mm_inc_nr_ptes(mm);
- return true;
}
vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
--
2.20.1
On Mon, Sep 30, 2019 at 12:55:28PM -0700, Ralph Campbell wrote:
> The return value from set_huge_zero_page() is never checked so simplify
> the code by making it return void.
>
> Signed-off-by: Ralph Campbell <[email protected]>
> ---
> mm/huge_memory.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index c5cb6dcd6c69..6cf0ee65538d 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -686,20 +686,18 @@ static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
> }
>
> /* Caller must hold page table lock. */
> -static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
> +static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
> struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
> struct page *zero_page)
> {
> pmd_t entry;
> - if (!pmd_none(*pmd))
> - return false;
> +
Wat? So you just bindly overwrite whatever is there?
NAK.
> entry = mk_pmd(zero_page, vma->vm_page_prot);
> entry = pmd_mkhuge(entry);
> if (pgtable)
> pgtable_trans_huge_deposit(mm, pmd, pgtable);
> set_pmd_at(mm, haddr, pmd, entry);
> mm_inc_nr_ptes(mm);
> - return true;
> }
>
> vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
> --
> 2.20.1
>
>
--
Kirill A. Shutemov
On 10/1/19 4:52 AM, Kirill A. Shutemov wrote:
> On Mon, Sep 30, 2019 at 12:55:28PM -0700, Ralph Campbell wrote:
>> The return value from set_huge_zero_page() is never checked so simplify
>> the code by making it return void.
>>
>> Signed-off-by: Ralph Campbell <[email protected]>
>> ---
>> mm/huge_memory.c | 6 ++----
>> 1 file changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>> index c5cb6dcd6c69..6cf0ee65538d 100644
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -686,20 +686,18 @@ static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
>> }
>>
>> /* Caller must hold page table lock. */
>> -static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
>> +static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
>> struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
>> struct page *zero_page)
>> {
>> pmd_t entry;
>> - if (!pmd_none(*pmd))
>> - return false;
>> +
>
> Wat? So you just bindly overwrite whatever is there?
>
> NAK.
No, the only two places it is called from are
do_huge_pmd_anonymous_page() which has the pmd_lock()
and already checked pmd_none() is true and
copy_huge_pmd() where the destination page table
is being filled in with no other threads accessing it.
I guess I should have put this analysis in the changelog.
Still, I guess putting a pmd_none() check in copy_huge_pmd()
as future proofing new callers of copy_huge_pmd() would
make sense.
>> entry = mk_pmd(zero_page, vma->vm_page_prot);
>> entry = pmd_mkhuge(entry);
>> if (pgtable)
>> pgtable_trans_huge_deposit(mm, pmd, pgtable);
>> set_pmd_at(mm, haddr, pmd, entry);
>> mm_inc_nr_ptes(mm);
>> - return true;
>> }
>>
>> vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
>> --
>> 2.20.1
>>
>>
>