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author | Jason Gunthorpe <jgg@mellanox.com> | 2020-03-05 15:26:33 -0400 |
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committer | Jason Gunthorpe <jgg@mellanox.com> | 2020-03-26 14:33:37 -0300 |
commit | 2288a9a68175cec9f91afb52948ba585b690774b (patch) | |
tree | aee7488ed3189342b3b5a5973c33058076100343 /mm/hmm.c | |
parent | 76612d6ce4ccd21329ce8c90dc51c5f747057b5b (diff) | |
download | lwn-2288a9a68175cec9f91afb52948ba585b690774b.tar.gz lwn-2288a9a68175cec9f91afb52948ba585b690774b.zip |
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: d08faca018c4 ("mm/hmm: properly handle migration pmd")
Fixes: da4c3c735ea4 ("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>
Diffstat (limited to 'mm/hmm.c')
-rw-r--r-- | mm/hmm.c | 38 |
1 files changed, 21 insertions, 17 deletions
@@ -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; |