Messages in this thread | | | Subject | Re: [PATCH 10/15] mm/hmm: do not differentiate between empty entry or missing directory v2 | From | John Hubbard <> | Date | Tue, 20 Mar 2018 22:24:34 -0700 |
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On 03/19/2018 07:00 PM, jglisse@redhat.com wrote: > From: Jérôme Glisse <jglisse@redhat.com> > > 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 <jglisse@redhat.com> > Cc: Evgeny Baskakov <ebaskakov@nvidia.com> > Cc: Ralph Campbell <rcampbell@nvidia.com> > Cc: Mark Hairgrove <mhairgrove@nvidia.com> > Cc: John Hubbard <jhubbard@nvidia.com> > --- > 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.
> if (hmm_vma_walk->fault) > goto fault; > continue; > @@ -489,8 +474,8 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, > > fault: > pte_unmap(ptep); > - /* Fault all pages in range */ > - return hmm_vma_walk_clear(start, end, walk); > + /* Fault any virtual address we were ask to fault */
asked to fault
thanks, -- John Hubbard NVIDIA
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