From: Jerome Glisse <jglisse@redhat.com>
To: John Hubbard <jhubbard@nvidia.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Evgeny Baskakov <ebaskakov@nvidia.com>,
Ralph Campbell <rcampbell@nvidia.com>,
Mark Hairgrove <mhairgrove@nvidia.com>
Subject: Re: [PATCH 10/15] mm/hmm: do not differentiate between empty entry or missing directory v2
Date: Wed, 21 Mar 2018 10:48:27 -0400 [thread overview]
Message-ID: <20180321144826.GA3214@redhat.com> (raw)
In-Reply-To: <4b0da5bb-4e44-798c-f4dd-cabc93cfeb99@nvidia.com>
On Tue, Mar 20, 2018 at 10:24:34PM -0700, John Hubbard wrote:
> On 03/19/2018 07:00 PM, jglisse@redhat.com wrote:
> > From: Jerome 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: Jerome 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.
>
The last patch do that so i don't think it is worth respinning
just to make this intermediate state prettier.
Cheers,
Jerome
next prev parent reply other threads:[~2018-03-21 14:48 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-20 2:00 [PATCH 00/15] hmm: fixes and documentations v3 jglisse
2018-03-20 2:00 ` [PATCH 01/15] mm/hmm: documentation editorial update to HMM documentation jglisse
2018-03-20 2:00 ` [PATCH 02/15] mm/hmm: fix header file if/else/endif maze v2 jglisse
2018-03-20 2:00 ` [PATCH 03/15] mm/hmm: HMM should have a callback before MM is destroyed v2 jglisse
2018-03-21 4:14 ` John Hubbard
2018-03-21 18:03 ` Jerome Glisse
2018-03-21 22:16 ` John Hubbard
2018-03-21 22:46 ` Jerome Glisse
2018-03-21 23:10 ` John Hubbard
2018-03-21 23:37 ` Jerome Glisse
2018-03-22 0:11 ` John Hubbard
2018-03-22 1:32 ` Jerome Glisse
2018-03-22 1:28 ` [PATCH 03/15] mm/hmm: HMM should have a callback before MM is destroyed v3 jglisse
2018-03-22 6:58 ` John Hubbard
2018-03-20 2:00 ` [PATCH 04/15] mm/hmm: unregister mmu_notifier when last HMM client quit jglisse
2018-03-21 4:24 ` John Hubbard
2018-03-21 18:12 ` Jerome Glisse
2018-03-21 18:16 ` [PATCH 04/15] mm/hmm: unregister mmu_notifier when last HMM client quit v2 jglisse
2018-03-21 23:22 ` John Hubbard
2018-03-21 23:41 ` Jerome Glisse
2018-03-22 22:47 ` John Hubbard
2018-03-22 23:37 ` Jerome Glisse
2018-03-23 0:13 ` John Hubbard
2018-03-23 0:50 ` Jerome Glisse
2018-03-23 0:56 ` John Hubbard
2018-03-22 1:30 ` [PATCH 04/15] mm/hmm: unregister mmu_notifier when last HMM client quit v3 jglisse
2018-03-22 22:36 ` Andrew Morton
2018-03-20 2:00 ` [PATCH 05/15] mm/hmm: hmm_pfns_bad() was accessing wrong struct jglisse
2018-03-20 2:00 ` [PATCH 06/15] mm/hmm: use struct for hmm_vma_fault(), hmm_vma_get_pfns() parameters v2 jglisse
2018-03-20 2:00 ` [PATCH 07/15] mm/hmm: remove HMM_PFN_READ flag and ignore peculiar architecture v2 jglisse
2018-03-20 2:00 ` [PATCH 08/15] mm/hmm: use uint64_t for HMM pfn instead of defining hmm_pfn_t to ulong v2 jglisse
2018-03-20 2:00 ` [PATCH 09/15] mm/hmm: cleanup special vma handling (VM_SPECIAL) jglisse
2018-03-20 2:00 ` [PATCH 10/15] mm/hmm: do not differentiate between empty entry or missing directory v2 jglisse
2018-03-21 5:24 ` John Hubbard
2018-03-21 14:48 ` Jerome Glisse [this message]
2018-03-21 23:16 ` John Hubbard
2018-03-20 2:00 ` [PATCH 11/15] mm/hmm: rename HMM_PFN_DEVICE_UNADDRESSABLE to HMM_PFN_DEVICE_PRIVATE jglisse
2018-03-20 2:00 ` [PATCH 12/15] mm/hmm: move hmm_pfns_clear() closer to where it is use jglisse
2018-03-20 2:00 ` [PATCH 13/15] mm/hmm: factor out pte and pmd handling to simplify hmm_vma_walk_pmd() jglisse
2018-03-21 5:07 ` John Hubbard
2018-03-21 15:08 ` Jerome Glisse
2018-03-21 22:36 ` John Hubbard
2018-03-20 2:00 ` [PATCH 14/15] mm/hmm: change hmm_vma_fault() to allow write fault on page basis jglisse
2018-03-20 2:00 ` [PATCH 15/15] mm/hmm: use device driver encoding for HMM pfn v2 jglisse
2018-03-21 4:39 ` John Hubbard
2018-03-21 15:52 ` Jerome Glisse
2018-03-21 23:19 ` John Hubbard
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