Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> wrote:
> From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com>
>
> We need to use smb_rmb when looking at hpte slot array. Otherwise we could
> reorder the hpte_slot array load bfore even we marked the pmd trans huge.
Does this need to go back into the stable series?
Mikey
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
> ---
> arch/powerpc/include/asm/pgtable-ppc64.h | 15 +++++++++++++++
> arch/powerpc/mm/hugepage-hash64.c | 6 +-----
> arch/powerpc/mm/pgtable_64.c | 6 +-----
> 3 files changed, 17 insertions(+), 10 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h
> b/arch/powerpc/include/asm/pgtable-ppc64.h
> index d046289..46db094 100644
> --- a/arch/powerpc/include/asm/pgtable-ppc64.h
> +++ b/arch/powerpc/include/asm/pgtable-ppc64.h
> @@ -10,6 +10,7 @@
> #else
> #include <asm/pgtable-ppc64-4k.h>
> #endif
> +#include <asm/barrier.h>
>
> #define FIRST_USER_ADDRESS 0
>
> @@ -393,6 +394,20 @@ static inline void mark_hpte_slot_valid(unsigned char
> *hpte_slot_array,
> hpte_slot_array[index] = hidx << 4 | 0x1 << 3;
> }
>
> +static inline char *get_hpte_slot_array(pmd_t *pmdp)
> +{
> + /*
> + * The hpte hindex is stored in the pgtable whose address is in the
> + * second half of the PMD
> + *
> + * Order this load with the test for pmd_trans_huge in the caller
> + */
> + smp_rmb();
> + return *(char **)(pmdp + PTRS_PER_PMD);
> +
> +
> +}
> +
> extern void hpte_do_hugepage_flush(struct mm_struct *mm, unsigned long addr,
> pmd_t *pmdp);
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> diff --git a/arch/powerpc/mm/hugepage-hash64.c
> b/arch/powerpc/mm/hugepage-hash64.c
> index e430766..c3ba3d5 100644
> --- a/arch/powerpc/mm/hugepage-hash64.c
> +++ b/arch/powerpc/mm/hugepage-hash64.c
> @@ -84,11 +84,7 @@ int __hash_page_thp(unsigned long ea, unsigned long
> access, unsigned long vsid,
>
> vpn = hpt_vpn(ea, vsid, ssize);
> hash = hpt_hash(vpn, shift, ssize);
> - /*
> - * The hpte hindex are stored in the pgtable whose address is in the
> - * second half of the PMD
> - */
> - hpte_slot_array = *(char **)(pmdp + PTRS_PER_PMD);
> + hpte_slot_array = get_hpte_slot_array(pmdp);
>
> valid = hpte_valid(hpte_slot_array, index);
> if (valid) {
> diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
> index 8dd7c83..19d6734 100644
> --- a/arch/powerpc/mm/pgtable_64.c
> +++ b/arch/powerpc/mm/pgtable_64.c
> @@ -701,11 +701,7 @@ void hpte_do_hugepage_flush(struct mm_struct *mm,
> unsigned long addr,
> * Flush all the hptes mapping this hugepage
> */
> s_addr = addr & HPAGE_PMD_MASK;
> - /*
> - * The hpte hindex are stored in the pgtable whose address is in the
> - * second half of the PMD
> - */
> - hpte_slot_array = *(char **)(pmdp + PTRS_PER_PMD);
> + hpte_slot_array = get_hpte_slot_array(pmdp);
> /*
> * IF we try to do a HUGE PTE update after a withdraw is done.
> * we will find the below NULL. This happens when we do
> --
> 1.8.1.2
>
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