There is a problem now:
CPU 0 CPU 1
pmdp_invalidate do_page_fault
... __handle_mm_fault
is_swap_pmd == true
trigger VM_BUG_ON() ?
set_pmd_at
the reason is when a pmd entry is invalidated by pmd_mkinvalid,
pmd_present should return true but now pmd_present return false.
Like arm64 does in
commit b65399f6111b ("arm64/mm: Change THP helpers to comply with
generic MM semantics"). we introduce a _PMD_PRESENT_INVALID_SHIFT
bit to check if a pmd is present but invalidated by pmd_mkinvalid.
After this commit pmd_present will return the correct value and
the VM_BUG_ON will not be triggered.
Signed-off-by: Hongchen Zhang <zhanghongchen@xxxxxxxxxxx>
---
arch/mips/include/asm/pgtable-64.h | 2 +-
arch/mips/include/asm/pgtable-bits.h | 2 ++
arch/mips/include/asm/pgtable.h | 3 +++
3 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/mips/include/asm/pgtable-64.h b/arch/mips/include/asm/pgtable-64.h
index 41921ac..050cf66 100644
--- a/arch/mips/include/asm/pgtable-64.h
+++ b/arch/mips/include/asm/pgtable-64.h
@@ -265,7 +265,7 @@ static inline int pmd_present(pmd_t pmd)
{
#ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
if (unlikely(pmd_val(pmd) & _PAGE_HUGE))
- return pmd_val(pmd) & _PAGE_PRESENT;
+ return pmd_val(pmd) & (_PAGE_PRESENT | _PMD_PRESENT_INVALID);
#endif
return pmd_val(pmd) != (unsigned long) invalid_pte_table;
diff --git a/arch/mips/include/asm/pgtable-bits.h b/arch/mips/include/asm/pgtable-bits.h
index 2362842..72cd88a 100644
--- a/arch/mips/include/asm/pgtable-bits.h
+++ b/arch/mips/include/asm/pgtable-bits.h
@@ -130,6 +130,7 @@ enum pgtable_bits {
_PAGE_MODIFIED_SHIFT,
#if defined(CONFIG_MIPS_HUGE_TLB_SUPPORT)
_PAGE_HUGE_SHIFT,
+ _PMD_PRESENT_INVALID_SHIFT,
#endif
#if defined(CONFIG_ARCH_HAS_PTE_SPECIAL)
_PAGE_SPECIAL_SHIFT,
@@ -157,6 +158,7 @@ enum pgtable_bits {
#define _PAGE_MODIFIED (1 << _PAGE_MODIFIED_SHIFT)
#if defined(CONFIG_MIPS_HUGE_TLB_SUPPORT)
# define _PAGE_HUGE (1 << _PAGE_HUGE_SHIFT)
+#define _PMD_PRESENT_INVALID (1 << _PMD_PRESENT_INVALID_SHIFT)
#endif
#if defined(CONFIG_ARCH_HAS_PTE_SPECIAL)
# define _PAGE_SPECIAL (1 << _PAGE_SPECIAL_SHIFT)
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 374c632..a75f461 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -696,12 +696,15 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
return pmd;
}
+#ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
static inline pmd_t pmd_mkinvalid(pmd_t pmd)
{
+ pmd_val(pmd) |= _PMD_PRESENT_INVALID;
pmd_val(pmd) &= ~(_PAGE_PRESENT | _PAGE_VALID | _PAGE_DIRTY);
return pmd;
}
+#endif
/*
* The generic version pmdp_huge_get_and_clear uses a version of pmd_clear() with a
--
1.8.3.1
