Re: [V3] powerpc/mm/hash64: memset the pagetable pages on allocation.

[Michael Ellerman <patch-notifications@ellerman.id.au>]

On Tue, 2018-02-13 at 11:09:33 UTC, "Aneesh Kumar K.V" wrote:
> On powerpc we allocate page table pages from slab cache of different sizes. For
> now we have a constructor that zero out the objects when we allocate then for
> the first time. We expect the objects to be zeroed out when we free the the
> object back to slab cache. This happens in the unmap path. For hugetlb pages
> we call huge_pte_get_and_clear to do that. With the current configuration of
> page table size, both pud and pgd level tables get allocated from the same slab
> cache. At the pud level, we use the second half of the table to store the slot
> information. But never clear that when unmapping. When such an freed object get
> allocated at pgd level, we will have part of the page table page not initlaized
> correctly. This result in kernel crash
> 
> Simplify this by calling the object initialization after kmem_cache_alloc
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/fc5c2f4a55a2c258e12013cdf287cf

cheers