From: John Hubbard <jhubbard@nvidia.com>
To: jglisse@redhat.com, linux-mm@kvack.org
Cc: 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: Tue, 20 Mar 2018 22:24:34 -0700 [thread overview]
Message-ID: <4b0da5bb-4e44-798c-f4dd-cabc93cfeb99@nvidia.com> (raw)
In-Reply-To: <20180320020038.3360-11-jglisse@redhat.com>
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
next prev parent reply other threads:[~2018-03-21 5:24 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 [this message]
2018-03-21 14:48 ` Jerome Glisse
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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