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@xxxxxxx> > Cc: Catalin Marinas <catalin.marinas@xxxxxxx> > Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> > Cc: Steve Capper <steve.capper@xxxxxxx> > Cc: Will Deacon <will.deacon@xxxxxxx> > Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > Cc: Michal Hocko <mhocko@xxxxxxxx> > Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> FWIW: Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx> Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
