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authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>2014-01-13 11:34:24 +0530
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-01-15 15:46:38 +1100
commitb3084f4db3aeb991c507ca774337c7e7893ed04f (patch)
treec5cad3a6843272a173e95a87a6087d362e19073e /arch/powerpc/include/asm/pgtable-ppc64.h
parenta6da83f98267bc8ee4e34aa899169991eb0ceb93 (diff)
powerpc/thp: Fix crash on mremap
This patch fix the below crash NIP [c00000000004cee4] .__hash_page_thp+0x2a4/0x440 LR [c0000000000439ac] .hash_page+0x18c/0x5e0 ... Call Trace: [c000000736103c40] [00001ffffb000000] 0x1ffffb000000(unreliable) [437908.479693] [c000000736103d50] [c0000000000439ac] .hash_page+0x18c/0x5e0 [437908.479699] [c000000736103e30] [c00000000000924c] .do_hash_page+0x4c/0x58 On ppc64 we use the pgtable for storing the hpte slot information and store address to the pgtable at a constant offset (PTRS_PER_PMD) from pmd. On mremap, when we switch the pmd, we need to withdraw and deposit the pgtable again, so that we find the pgtable at PTRS_PER_PMD offset from new pmd. We also want to move the withdraw and deposit before the set_pmd so that, when page fault find the pmd as trans huge we can be sure that pgtable can be located at the offset. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/include/asm/pgtable-ppc64.h')
-rw-r--r--arch/powerpc/include/asm/pgtable-ppc64.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h
index 4a191c47286..d27960c89a7 100644
--- a/arch/powerpc/include/asm/pgtable-ppc64.h
+++ b/arch/powerpc/include/asm/pgtable-ppc64.h
@@ -558,5 +558,19 @@ extern pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp);
#define __HAVE_ARCH_PMDP_INVALIDATE
extern void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp);
+
+#define pmd_move_must_withdraw pmd_move_must_withdraw
+typedef struct spinlock spinlock_t;
+static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
+ spinlock_t *old_pmd_ptl)
+{
+ /*
+ * Archs like ppc64 use pgtable to store per pmd
+ * specific information. So when we switch the pmd,
+ * we should also withdraw and deposit the pgtable
+ */
+ return true;
+}
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_POWERPC_PGTABLE_PPC64_H_ */