On Tue, Mar 20, 2018 at 10:24:34PM -0700, John Hubbard wrote: > On 03/19/2018 07:00 PM, [email protected] wrote: > > From: Jérôme Glisse <[email protected]> > > > > There is no point in differentiating between a range for which there > > is not even a directory (and thus entries) and empty entry (pte_none() > > or pmd_none() returns true). > > > > Simply drop the distinction ie remove HMM_PFN_EMPTY flag and merge now > > duplicate hmm_vma_walk_hole() and hmm_vma_walk_clear() functions. > > > > Changed since v1: > > - Improved comments > > > > Signed-off-by: Jérôme Glisse <[email protected]> > > Cc: Evgeny Baskakov <[email protected]> > > Cc: Ralph Campbell <[email protected]> > > Cc: Mark Hairgrove <[email protected]> > > Cc: John Hubbard <[email protected]> > > --- > > include/linux/hmm.h | 8 +++----- > > mm/hmm.c | 45 +++++++++++++++------------------------------ > > 2 files changed, 18 insertions(+), 35 deletions(-) > > > > diff --git a/include/linux/hmm.h b/include/linux/hmm.h > > index 54d684fe3b90..cf283db22106 100644 > > --- a/include/linux/hmm.h > > +++ b/include/linux/hmm.h > > @@ -84,7 +84,6 @@ struct hmm; > > * HMM_PFN_VALID: pfn is valid. It has, at least, read permission. > > * HMM_PFN_WRITE: CPU page table has write permission set > > * HMM_PFN_ERROR: corresponding CPU page table entry points to poisoned > > memory > > - * HMM_PFN_EMPTY: corresponding CPU page table entry is pte_none() > > * HMM_PFN_SPECIAL: corresponding CPU page table entry is special; i.e., > > the > > * result of vm_insert_pfn() or vm_insert_page(). Therefore, it > > should not > > * be mirrored by a device, because the entry will never have > > HMM_PFN_VALID > > @@ -94,10 +93,9 @@ struct hmm; > > #define HMM_PFN_VALID (1 << 0) > > #define HMM_PFN_WRITE (1 << 1) > > #define HMM_PFN_ERROR (1 << 2) > > -#define HMM_PFN_EMPTY (1 << 3) > > Hi Jerome, > > Nearly done with this one...see below for a bit more detail, but I think if > we did this: > > #define HMM_PFN_EMPTY (0) > > ...it would work out nicely. > > > -#define HMM_PFN_SPECIAL (1 << 4) > > -#define HMM_PFN_DEVICE_UNADDRESSABLE (1 << 5) > > -#define HMM_PFN_SHIFT 6 > > +#define HMM_PFN_SPECIAL (1 << 3) > > +#define HMM_PFN_DEVICE_UNADDRESSABLE (1 << 4) > > +#define HMM_PFN_SHIFT 5 > > > > <snip> > > > @@ -438,7 +423,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, > > pfns[i] = 0; > > > > if (pte_none(pte)) { > > - pfns[i] = HMM_PFN_EMPTY; > > + pfns[i] = 0; > > This works, but why not keep HMM_PFN_EMPTY, and just define it as zero? > Symbols are better than raw numbers here. >
The last patch do that so i don't think it is worth respinning just to make this intermediate state prettier. Cheers, Jérôme
