On 3/11/20 11:35 AM, Jason Gunthorpe wrote:
From: Jason Gunthorpe jgg@mellanox.com
Currently if a special PTE is encountered hmm_range_fault() immediately returns EFAULT and sets the HMM_PFN_SPECIAL error output (which nothing uses).
EFAULT should only be returned after testing with hmm_pte_need_fault().
Also pte_devmap() and pte_special() are exclusive, and there is no need to check IS_ENABLED, pte_special() is stubbed out to return false on unsupported architectures.
Fixes: 992de9a8b751 ("mm/hmm: allow to mirror vma of a file on a DAX backed filesystem") Signed-off-by: Jason Gunthorpe jgg@mellanox.com
Reviewed-by: Ralph Campbell rcampbell@nvidia.com
mm/hmm.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/mm/hmm.c b/mm/hmm.c index f61fddf2ef6505..ca33d086bdc190 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -335,16 +335,21 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, pte_unmap(ptep); return -EBUSY; }
- } else if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && pte_special(pte)) {
if (!is_zero_pfn(pte_pfn(pte))) {
- }
- /*
* Since each architecture defines a struct page for the zero page, just* fall through and treat it like a normal page.*/- if (pte_special(pte) && !is_zero_pfn(pte_pfn(pte))) {
hmm_pte_need_fault(hmm_vma_walk, orig_pfn, 0, &fault,&write_fault);if (fault || write_fault) { pte_unmap(ptep);
*pfn = range->values[HMM_PFN_SPECIAL]; return -EFAULT;/** Since each architecture defines a struct page for the zero* page, just fall through and treat it like a normal page.*/
*pfn = range->values[HMM_PFN_SPECIAL];return 0;}
*pfn = hmm_device_entry_from_pfn(range, pte_pfn(pte)) | cpu_flags;