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mm/hmm: return -EFAULT when setting HMM_PFN_ERROR on requested valid pages 

hmm_range_fault() should never return 0 if the caller requested a valid
page, but the pfns output for that page would be HMM_PFN_ERROR.

hmm_pte_need_fault() must always be called before setting HMM_PFN_ERROR to
detect if the page is in faulting mode or not.

Fix two cases in hmm_vma_walk_pmd() and reorganize some of the duplicated
code.

Fixes: d08faca018 ("mm/hmm: properly handle migration pmd")
Fixes: da4c3c735e ("mm/hmm/mirror: helper to snapshot CPU page table")
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Jason Gunthorpe 2020-03-05 15:26:33 -04:00
parent 76612d6ce4
commit 2288a9a681
1 changed files with 21 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
mm/hmm.c
View File

@ -371,8 +371,10 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
{
struct hmm_vma_walk *hmm_vma_walk = walk->private;
struct hmm_range *range = hmm_vma_walk->range;
uint64_t *pfns = range->pfns;
unsigned long addr = start, i;
uint64_t *pfns = &range->pfns[(start - range->start) >> PAGE_SHIFT];
unsigned long npages = (end - start) >> PAGE_SHIFT;
unsigned long addr = start;
bool fault, write_fault;
pte_t *ptep;
pmd_t pmd;
@ -382,14 +384,6 @@ again:
return hmm_vma_walk_hole(start, end, -1, walk);
if (thp_migration_supported() && is_pmd_migration_entry(pmd)) {
bool fault, write_fault;
unsigned long npages;
uint64_t *pfns;
i = (addr - range->start) >> PAGE_SHIFT;
npages = (end - addr) >> PAGE_SHIFT;
pfns = &range->pfns[i];
hmm_range_need_fault(hmm_vma_walk, pfns, npages,
0, &fault, &write_fault);
if (fault || write_fault) {
@ -398,8 +392,15 @@ again:
return -EBUSY;
}
return hmm_pfns_fill(start, end, range, HMM_PFN_NONE);
} else if (!pmd_present(pmd))
}
if (!pmd_present(pmd)) {
hmm_range_need_fault(hmm_vma_walk, pfns, npages, 0, &fault,
&write_fault);
if (fault || write_fault)
return -EFAULT;
return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR);
}
if (pmd_devmap(pmd) || pmd_trans_huge(pmd)) {
/*
@ -416,8 +417,7 @@ again:
if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd))
goto again;
i = (addr - range->start) >> PAGE_SHIFT;
return hmm_vma_handle_pmd(walk, addr, end, &pfns[i], pmd);
return hmm_vma_handle_pmd(walk, addr, end, pfns, pmd);
}
/*
@ -426,15 +426,19 @@ again:
* entry pointing to pte directory or it is a bad pmd that will not
* recover.
*/
if (pmd_bad(pmd))
if (pmd_bad(pmd)) {
hmm_range_need_fault(hmm_vma_walk, pfns, npages, 0, &fault,
&write_fault);
if (fault || write_fault)
return -EFAULT;
return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR);
}
ptep = pte_offset_map(pmdp, addr);
i = (addr - range->start) >> PAGE_SHIFT;
for (; addr < end; addr += PAGE_SIZE, ptep++, i++) {
for (; addr < end; addr += PAGE_SIZE, ptep++, pfns++) {
int r;
r = hmm_vma_handle_pte(walk, addr, end, pmdp, ptep, &pfns[i]);
r = hmm_vma_handle_pte(walk, addr, end, pmdp, ptep, pfns);
if (r) {
/* hmm_vma_handle_pte() did pte_unmap() */
hmm_vma_walk->last = addr;