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. Will
