diff options
| author | Alistair Popple <[email protected]> | 2022-09-02 10:35:51 +1000 |
|---|---|---|
| committer | Andrew Morton <[email protected]> | 2022-09-11 16:22:30 -0700 |
| commit | 60bae73708963de4a17231077285bd9ff2f41c44 (patch) | |
| tree | bcc79ab6765df5cb1c5e8d444e655150354b2965 | |
| parent | 818c4fdaa98769ce2d0bf64bc50a6c9af89290ea (diff) | |
mm/migrate_device.c: flush TLB while holding PTL
When clearing a PTE the TLB should be flushed whilst still holding the PTL
to avoid a potential race with madvise/munmap/etc. For example consider
the following sequence:
CPU0 CPU1
---- ----
migrate_vma_collect_pmd()
pte_unmap_unlock()
madvise(MADV_DONTNEED)
-> zap_pte_range()
pte_offset_map_lock()
[ PTE not present, TLB not flushed ]
pte_unmap_unlock()
[ page is still accessible via stale TLB ]
flush_tlb_range()
In this case the page may still be accessed via the stale TLB entry after
madvise returns. Fix this by flushing the TLB while holding the PTL.
Fixes: 8c3328f1f36a ("mm/migrate: migrate_vma() unmap page from vma while collecting pages")
Link: https://lkml.kernel.org/r/9f801e9d8d830408f2ca27821f606e09aa856899.1662078528.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple <[email protected]>
Reported-by: Nadav Amit <[email protected]>
Reviewed-by: "Huang, Ying" <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Acked-by: Peter Xu <[email protected]>
Cc: Alex Sierra <[email protected]>
Cc: Ben Skeggs <[email protected]>
Cc: Felix Kuehling <[email protected]>
Cc: huang ying <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Karol Herbst <[email protected]>
Cc: Logan Gunthorpe <[email protected]>
Cc: Lyude Paul <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Ralph Campbell <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
| -rw-r--r-- | mm/migrate_device.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/mm/migrate_device.c b/mm/migrate_device.c index 27fb37d65476..6a5ef9f0da6a 100644 --- a/mm/migrate_device.c +++ b/mm/migrate_device.c @@ -254,13 +254,14 @@ next: migrate->dst[migrate->npages] = 0; migrate->src[migrate->npages++] = mpfn; } - arch_leave_lazy_mmu_mode(); - pte_unmap_unlock(ptep - 1, ptl); /* Only flush the TLB if we actually modified any entries */ if (unmapped) flush_tlb_range(walk->vma, start, end); + arch_leave_lazy_mmu_mode(); + pte_unmap_unlock(ptep - 1, ptl); + return 0; } |