Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> wrote:
> From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com>
>
> Book3E uses the hugepd at PMD level and don't encode pte directly
> at the pmd level. So it will find the lower bits of pmd set
> and the pmd_bad check throws error. Infact the current code
> will never take the free_hugepd_range call at all because it will
> clear the pmd if it find a hugepd pointer.
>
Please explain what changes you are making. Currently you are only
describing what the issue is.
Also include which the SHA1 which caused the regression (ie
e2b3d202d1dba8f3546ed28224ce485bc50010be "powerpc: Switch 16GB and 16MB
explicit hugepages to a different page table format")
Mikey
> Reported-by: Scott Wood <scottw...@freescale.com>
> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
> ---
> arch/powerpc/mm/hugetlbpage.c | 29 ++++++++++++++++++-----------
> 1 file changed, 18 insertions(+), 11 deletions(-)
>
> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
> index f2f01fd..0d3d3ee 100644
> --- a/arch/powerpc/mm/hugetlbpage.c
> +++ b/arch/powerpc/mm/hugetlbpage.c
> @@ -536,19 +536,26 @@ static void hugetlb_free_pmd_range(struct mmu_gather
> *tlb, pud_t *pud,
> do {
> pmd = pmd_offset(pud, addr);
> next = pmd_addr_end(addr, end);
> - if (pmd_none_or_clear_bad(pmd))
> - continue;
> + if (!is_hugepd(pmd)) {
> + /*
> + * if it is not hugepd pointer, we should already find
> + * it cleared.
> + */
> + if (!pmd_none_or_clear_bad(pmd))
> + WARN_ON(1);
How often are we going to hit this? Should this be a warn_on once or
even a bug_on?
Also just make it:
WARN_ON(!pmd_none_or_clear_bad(pmd))
Mikey
> + } else {
> #ifdef CONFIG_PPC_FSL_BOOK3E
> - /*
> - * Increment next by the size of the huge mapping since
> - * there may be more than one entry at this level for a
> - * single hugepage, but all of them point to
> - * the same kmem cache that holds the hugepte.
> - */
> - next = addr + (1 << hugepd_shift(*(hugepd_t *)pmd));
> + /*
> + * Increment next by the size of the huge mapping since
> + * there may be more than one entry at this level for a
> + * single hugepage, but all of them point to
> + * the same kmem cache that holds the hugepte.
> + */
> + next = addr + (1 << hugepd_shift(*(hugepd_t *)pmd));
> #endif
> - free_hugepd_range(tlb, (hugepd_t *)pmd, PMD_SHIFT,
> - addr, next, floor, ceiling);
> + free_hugepd_range(tlb, (hugepd_t *)pmd, PMD_SHIFT,
> + addr, next, floor, ceiling);
> + }
> } while (addr = next, addr != end);
>
> start &= PUD_MASK;
> --
> 1.8.1.2
>
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