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| author | Nicholas Piggin <npiggin@gmail.com> | 2019-06-07 13:56:36 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2019-06-07 16:28:28 +1000 |
| commit | a00196a272161338d4b1d66ec69e3d57c6b280e0 (patch) | |
| tree | 8c1b21d16a2fede66919f4809292087fde2a3215 | |
| parent | 33258a1db165cf43a9e6382587ad06e9b7f8187c (diff) | |
| download | linux-a00196a272161338d4b1d66ec69e3d57c6b280e0.tar.bz2 | |
powerpc/64s: __find_linux_pte() synchronization vs pmdp_invalidate()
The change to pmdp_invalidate() to mark the pmd with _PAGE_INVALID
broke the synchronisation against lock free lookups,
__find_linux_pte()'s pmd_none() check no longer returns true for such
cases.
Fix this by adding a check for this condition as well.
Fixes: da7ad366b497 ("powerpc/mm/book3s: Update pmd_present to look at _PAGE_PRESENT bit")
Cc: stable@vger.kernel.org # v4.20+
Suggested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
| -rw-r--r-- | arch/powerpc/mm/pgtable.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c index db4a6253df92..533fc6fa6726 100644 --- a/arch/powerpc/mm/pgtable.c +++ b/arch/powerpc/mm/pgtable.c @@ -372,13 +372,25 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea, pdshift = PMD_SHIFT; pmdp = pmd_offset(&pud, ea); pmd = READ_ONCE(*pmdp); + /* - * A hugepage collapse is captured by pmd_none, because - * it mark the pmd none and do a hpte invalidate. + * A hugepage collapse is captured by this condition, see + * pmdp_collapse_flush. */ if (pmd_none(pmd)) return NULL; +#ifdef CONFIG_PPC_BOOK3S_64 + /* + * A hugepage split is captured by this condition, see + * pmdp_invalidate. + * + * Huge page modification can be caught here too. + */ + if (pmd_is_serializing(pmd)) + return NULL; +#endif + if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) { if (is_thp) *is_thp = true; |