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Message-ID: <20190807175111.GK1571@mellanox.com>
Date: Wed, 7 Aug 2019 17:51:15 +0000
From: Jason Gunthorpe <jgg@...lanox.com>
To: Christoph Hellwig <hch@....de>
CC: Jérôme Glisse <jglisse@...hat.com>,
Ben Skeggs <bskeggs@...hat.com>,
Felix Kuehling <Felix.Kuehling@....com>,
Ralph Campbell <rcampbell@...dia.com>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"nouveau@...ts.freedesktop.org" <nouveau@...ts.freedesktop.org>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
"amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 07/15] mm: remove the page_shift member from struct
hmm_range
On Tue, Aug 06, 2019 at 07:05:45PM +0300, Christoph Hellwig wrote:
> All users pass PAGE_SIZE here, and if we wanted to support single
> entries for huge pages we should really just add a HMM_FAULT_HUGEPAGE
> flag instead that uses the huge page size instead of having the
> caller calculate that size once, just for the hmm code to verify it.
>
> Signed-off-by: Christoph Hellwig <hch@....de>
> Acked-by: Felix Kuehling <Felix.Kuehling@....com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 1 -
> drivers/gpu/drm/nouveau/nouveau_svm.c | 1 -
> include/linux/hmm.h | 22 -------------
> mm/hmm.c | 42 ++++++-------------------
> 4 files changed, 9 insertions(+), 57 deletions(-)
Having looked at ODP more closley this doesn't seem to match what it
needs anyhow. It can keep using its checking algorithm
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 71d6e7087b0b..8bf79288c4e2 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -818,7 +818,6 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
> 0 : range->flags[HMM_PFN_WRITE];
> range->pfn_flags_mask = 0;
> range->pfns = pfns;
> - range->page_shift = PAGE_SHIFT;
> range->start = start;
> range->end = start + ttm->num_pages * PAGE_SIZE;
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
> index 41fad4719ac6..668d4bd0c118 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_svm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
> @@ -680,7 +680,6 @@ nouveau_svm_fault(struct nvif_notify *notify)
> args.i.p.addr + args.i.p.size, fn - fi);
>
> /* Have HMM fault pages within the fault window to the GPU. */
> - range.page_shift = PAGE_SHIFT;
> range.start = args.i.p.addr;
> range.end = args.i.p.addr + args.i.p.size;
> range.pfns = args.phys;
> diff --git a/include/linux/hmm.h b/include/linux/hmm.h
> index c5b51376b453..51e18fbb8953 100644
> --- a/include/linux/hmm.h
> +++ b/include/linux/hmm.h
> @@ -158,7 +158,6 @@ enum hmm_pfn_value_e {
> * @values: pfn value for some special case (none, special, error, ...)
> * @default_flags: default flags for the range (write, read, ... see hmm doc)
> * @pfn_flags_mask: allows to mask pfn flags so that only default_flags matter
> - * @page_shift: device virtual address shift value (should be >= PAGE_SHIFT)
> * @pfn_shifts: pfn shift value (should be <= PAGE_SHIFT)
> * @valid: pfns array did not change since it has been fill by an HMM function
> */
> @@ -172,31 +171,10 @@ struct hmm_range {
> const uint64_t *values;
> uint64_t default_flags;
> uint64_t pfn_flags_mask;
> - uint8_t page_shift;
> uint8_t pfn_shift;
> bool valid;
> };
>
> -/*
> - * hmm_range_page_shift() - return the page shift for the range
> - * @range: range being queried
> - * Return: page shift (page size = 1 << page shift) for the range
> - */
> -static inline unsigned hmm_range_page_shift(const struct hmm_range *range)
> -{
> - return range->page_shift;
> -}
> -
> -/*
> - * hmm_range_page_size() - return the page size for the range
> - * @range: range being queried
> - * Return: page size for the range in bytes
> - */
> -static inline unsigned long hmm_range_page_size(const struct hmm_range *range)
> -{
> - return 1UL << hmm_range_page_shift(range);
> -}
> -
> /*
> * hmm_range_wait_until_valid() - wait for range to be valid
> * @range: range affected by invalidation to wait on
> diff --git a/mm/hmm.c b/mm/hmm.c
> index 926735a3aef9..f26d6abc4ed2 100644
> --- a/mm/hmm.c
> +++ b/mm/hmm.c
> @@ -344,13 +344,12 @@ static int hmm_vma_walk_hole_(unsigned long addr, unsigned long end,
> struct hmm_vma_walk *hmm_vma_walk = walk->private;
> struct hmm_range *range = hmm_vma_walk->range;
> uint64_t *pfns = range->pfns;
> - unsigned long i, page_size;
> + unsigned long i;
>
> hmm_vma_walk->last = addr;
> - page_size = hmm_range_page_size(range);
> - i = (addr - range->start) >> range->page_shift;
> + i = (addr - range->start) >> PAGE_SHIFT;
>
> - for (; addr < end; addr += page_size, i++) {
> + for (; addr < end; addr += PAGE_SIZE, i++) {
> pfns[i] = range->values[HMM_PFN_NONE];
> if (fault || write_fault) {
> int ret;
> @@ -772,7 +771,7 @@ static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
> struct mm_walk *walk)
> {
> #ifdef CONFIG_HUGETLB_PAGE
> - unsigned long addr = start, i, pfn, mask, size, pfn_inc;
> + unsigned long addr = start, i, pfn, mask;
> struct hmm_vma_walk *hmm_vma_walk = walk->private;
> struct hmm_range *range = hmm_vma_walk->range;
> struct vm_area_struct *vma = walk->vma;
> @@ -783,24 +782,12 @@ static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
> pte_t entry;
> int ret = 0;
>
> - size = huge_page_size(h);
> - mask = size - 1;
> - if (range->page_shift != PAGE_SHIFT) {
> - /* Make sure we are looking at a full page. */
> - if (start & mask)
> - return -EINVAL;
> - if (end < (start + size))
> - return -EINVAL;
> - pfn_inc = size >> PAGE_SHIFT;
> - } else {
> - pfn_inc = 1;
> - size = PAGE_SIZE;
> - }
> + mask = huge_page_size(h) - 1;
>
> ptl = huge_pte_lock(hstate_vma(vma), walk->mm, pte);
> entry = huge_ptep_get(pte);
>
> - i = (start - range->start) >> range->page_shift;
> + i = (start - range->start) >> PAGE_SHIFT;
> orig_pfn = range->pfns[i];
> range->pfns[i] = range->values[HMM_PFN_NONE];
> cpu_flags = pte_to_hmm_pfn_flags(range, entry);
> @@ -812,8 +799,8 @@ static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
> goto unlock;
> }
>
> - pfn = pte_pfn(entry) + ((start & mask) >> range->page_shift);
> - for (; addr < end; addr += size, i++, pfn += pfn_inc)
> + pfn = pte_pfn(entry) + ((start & mask) >> PAGE_SHIFT);
> + for (; addr < end; addr += PAGE_SIZE, i++, pfn++)
> range->pfns[i] = hmm_device_entry_from_pfn(range, pfn) |
> cpu_flags;
> hmm_vma_walk->last = end;
> @@ -850,14 +837,13 @@ static void hmm_pfns_clear(struct hmm_range *range,
> */
> int hmm_range_register(struct hmm_range *range, struct hmm_mirror *mirror)
> {
> - unsigned long mask = ((1UL << range->page_shift) - 1UL);
> struct hmm *hmm = mirror->hmm;
> unsigned long flags;
>
> range->valid = false;
> range->hmm = NULL;
>
> - if ((range->start & mask) || (range->end & mask))
> + if ((range->start & (PAGE_SIZE - 1)) || (range->end & (PAGE_SIZE - 1)))
> return -EINVAL;
PAGE_SIZE-1 == PAGE_MASK ? If yes I can fix it
Reviewed-by: Jason Gunthorpe <jgg@...lanox.com>
Jason
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