On 08/27/2020 01:34 PM, Aneesh Kumar K.V wrote:
> With the hash page table, the kernel should not use pmd_clear for clearing
> huge pte entries. Add a DEBUG_VM WARN to catch the wrong usage.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
> ---
> arch/powerpc/include/asm/book3s/64/pgtable.h | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index 6de56c3b33c4..079211968987 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -868,6 +868,13 @@ static inline bool pte_ci(pte_t pte)
>
> static inline void pmd_clear(pmd_t *pmdp)
> {
> + if (IS_ENABLED(CONFIG_DEBUG_VM) && !radix_enabled()) {
> + /*
> + * Don't use this if we can possibly have a hash page table
> + * entry mapping this.
> + */
> + WARN_ON((pmd_val(*pmdp) & (H_PAGE_HASHPTE | _PAGE_PTE)) == (H_PAGE_HASHPTE | _PAGE_PTE));
> + }
> *pmdp = __pmd(0);
> }
>
> @@ -916,6 +923,13 @@ static inline int pmd_bad(pmd_t pmd)
>
> static inline void pud_clear(pud_t *pudp)
> {
> + if (IS_ENABLED(CONFIG_DEBUG_VM) && !radix_enabled()) {
> + /*
> + * Don't use this if we can possibly have a hash page table
> + * entry mapping this.
> + */
> + WARN_ON((pud_val(*pudp) & (H_PAGE_HASHPTE | _PAGE_PTE)) == (H_PAGE_HASHPTE | _PAGE_PTE));
> + }
> *pudp = __pud(0);
> }
There are two checkpatch.pl warnings for this patch.
WARNING: line length of 105 exceeds 100 columns
#27: FILE: arch/powerpc/include/asm/book3s/64/pgtable.h:876:
+ WARN_ON((pmd_val(*pmdp) & (H_PAGE_HASHPTE | _PAGE_PTE)) == (H_PAGE_HASHPTE | _PAGE_PTE));
WARNING: line length of 105 exceeds 100 columns
#41: FILE: arch/powerpc/include/asm/book3s/64/pgtable.h:931:
+ WARN_ON((pud_val(*pudp) & (H_PAGE_HASHPTE | _PAGE_PTE)) == (H_PAGE_HASHPTE | _PAGE_PTE));
total: 0 errors, 2 warnings, 26 lines checked
