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mm/hmm.c: allow VM_MIXEDMAP to work with hmm_range_fault

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hmm_range_fault() can be used instead of get_user_pages() for devices
which allow faulting however unlike get_user_pages() it will return an
error when used on a VM_MIXEDMAP range.

To make hmm_range_fault() more closely match get_user_pages() remove
this restriction.  This requires dealing with the !ARCH_HAS_PTE_SPECIAL
case in hmm_vma_handle_pte().  Rather than replicating the logic of
vm_normal_page() call it directly and do a check for the zero pfn
similar to what get_user_pages() currently does.

Also add a test to hmm selftest to verify functionality.

Link: https://lkml.kernel.org/r/20211104012001.2555676-1-apopple@nvidia.com
Fixes: da4c3c735e ("mm/hmm/mirror: helper to snapshot CPU page table")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alistair Popple
2022-01-14 14:09:31 -08:00
committed by Linus Torvalds
parent cab0a7c115
commit 87c01d57fa
3 changed files with 69 additions and 2 deletions
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24
lib/test_hmm.c
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@@ -1086,9 +1086,33 @@ static long dmirror_fops_unlocked_ioctl(struct file *filp,
return 0;
}
static int dmirror_fops_mmap(struct file *file, struct vm_area_struct *vma)
{
unsigned long addr;
for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) {
struct page *page;
int ret;
page = alloc_page(GFP_KERNEL | __GFP_ZERO);
if (!page)
return -ENOMEM;
ret = vm_insert_page(vma, addr, page);
if (ret) {
__free_page(page);
return ret;
}
put_page(page);
}
return 0;
}
static const struct file_operations dmirror_fops = {
.open = dmirror_fops_open,
.release = dmirror_fops_release,
.mmap = dmirror_fops_mmap,
.unlocked_ioctl = dmirror_fops_unlocked_ioctl,
.llseek = default_llseek,
.owner = THIS_MODULE,