Messages in this thread | | | Date | Tue, 22 Aug 2017 11:11:18 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH v2] mm/hugetlb.c: make huge_pte_offset() consistent and document behaviour |
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On Fri, Aug 18, 2017 at 03:54:15PM +0100, Punit Agrawal wrote: > When walking the page tables to resolve an address that points to > !p*d_present() entry, huge_pte_offset() returns inconsistent values > depending on the level of page table (PUD or PMD). > > It returns NULL in the case of a PUD entry while in the case of a PMD > entry, it returns a pointer to the page table entry. > > A similar inconsitency exists when handling swap entries - returns NULL > for a PUD entry while a pointer to the pte_t is retured for the PMD entry. > > Update huge_pte_offset() to make the behaviour consistent - return a > pointer to the pte_t for hugepage or swap entries. Only return NULL in > instances where we have a p*d_none() entry and the size parameter > doesn't match the hugepage size at this level of the page table. > > Document the behaviour to clarify the expected behaviour of this function. > This is to set clear semantics for architecture specific implementations > of huge_pte_offset(). > > Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > Cc: Steve Capper <steve.capper@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Cc: Michal Hocko <mhocko@suse.com> > Cc: Mike Kravetz <mike.kravetz@oracle.com>
FWIW:
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Thanks.
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