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SubjectRe: + x86-add-support-for-pud-sized-transparent-hugepages-checkpatch-fixes.patch added to -mm tree
On Wed, Mar 09, 2016 at 03:03:45PM -0500, Matthew Wilcox wrote:
> On Wed, Mar 09, 2016 at 01:45:40PM -0500, Matthew Wilcox wrote:
> > > In fact even before starting to fix the comment, I would recommend to
> > > try again to call native_local_pmdp_get_and_clear and
> > > native_local_ptep_get_and_clear to verify if it still breaks, just in
> > > case the include ordering got fixed by accident in the meanwhile (that
> > > was a comment in 2.6.25 when arch/x86/include/asm didn't even exist
> > > yet, it was still in include/asm-x86). If it would manage to build
> > > without the manual expansion, the comment could go and the duplication
> > > as well.
> >
> > The ordering problem is still there. native_local_ptep_get_and_clear()
> > is declared at line 726 of asm/pgtable.h and asm/pgtable_64.h is included
> > at line 466 of asm/pgtable.h.
> >
> > I'll have a little play; see if I can resolve this ...
>
> asm/pgtable.h:466
> # include <asm/pgtable_64.h>
>
> asm/pgtable.h:726
> static inline pte_t native_local_ptep_get_and_clear(pte_t *ptep)
> {
> pte_t res = *ptep;
>
> /* Pure native function needs no input for mm, addr */
> native_pte_clear(NULL, 0, ptep);
> return res;
> }
>
> asm/pgtable_64.h:47
> static inline void native_pte_clear(struct mm_struct *mm, unsigned long addr,
> pte_t *ptep)
> {
> *ptep = native_make_pte(0);
> }
>
> asm/pgtable_64.h:73
> static inline pte_t native_ptep_get_and_clear(pte_t *xp)
> {
> #ifdef CONFIG_SMP
> return native_make_pte(xchg(&xp->pte, 0));
> #else
> /* native_local_ptep_get_and_clear,
> but duplicated because of cyclic dependency */
> pte_t ret = *xp;
> native_pte_clear(NULL, 0, xp);
> return ret;
> #endif
> }
>
> Why don't we just convert native_ptep_get_and_clear to work the same way that
> pgtable-2level and pgtable-3level work? ie:
>
> #ifdef CONFIG_SMP
> static inline pte_t native_ptep_get_and_clear(pte_t *xp)
> {
> return native_make_pte(xchg(&xp->pte, 0));
> }
> #else
> #define native_ptep_get_and_clear(xp) native_local_ptep_get_and_clear(xp)
> #endif
>
> Or perhaps better, centralise the non-SMP definitions:
>
> arch/x86/include/asm/pgtable-2level.h | 6 ------
> arch/x86/include/asm/pgtable-3level.h | 7 +------
> arch/x86/include/asm/pgtable.h | 5 +++++
> arch/x86/include/asm/pgtable_64.h | 18 ++----------------
> 4 files changed, 8 insertions(+), 28 deletions(-)

Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>

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