On Mon, 2018-09-17 at 12:33 +0100, Will Deacon wrote: > On Fri, Sep 14, 2018 at 08:37:48PM +0000, Kani, Toshi wrote: > > On Wed, 2018-09-12 at 11:26 +0100, Will Deacon wrote: > > > Now that the core code checks this for us, we don't need to do it in the > > > backend. > > > > > > Cc: Chintan Pandya <cpandya@xxxxxxxxxxxxxx> > > > Cc: Toshi Kani <toshi.kani@xxxxxxx> > > > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > > > Cc: Michal Hocko <mhocko@xxxxxxxx> > > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > > Signed-off-by: Will Deacon <will.deacon@xxxxxxx> > > > --- > > > arch/x86/mm/pgtable.c | 6 ------ > > > 1 file changed, 6 deletions(-) > > > > > > diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c > > > index ae394552fb94..b4919c44a194 100644 > > > --- a/arch/x86/mm/pgtable.c > > > +++ b/arch/x86/mm/pgtable.c > > > @@ -796,9 +796,6 @@ int pud_free_pmd_page(pud_t *pud, unsigned long addr) > > > pte_t *pte; > > > int i; > > > > > > - if (pud_none(*pud)) > > > - return 1; > > > - > > > > Do we need to remove this safe guard? I feel list this is same as > > kfree() accepting NULL. > > I think two big differences with kfree() are (1) that this function has > exactly one caller in the tree and (2) it's implemented per-arch. Therefore > we're in a good position to give it some simple semantics and implement > those. Of course, if the x86 people would like to keep the redundant check, > that's up to them, but I think it makes the function more confusing and > tempts people into calling it for present entries. With patch 1/5 change to have pXd_present() check, I agree that we can remove this pXd_none() check to avoid any confusion. Reviewed-by: Toshi Kani <toshi.kani@xxxxxxx> Thanks, -Toshi
