From: Liu Shixin <liushixin2@xxxxxxxxxx>
commit 74c2f81054510d45b813548cb0a1c4ebf87cdd5f upstream.
The page table check trigger BUG_ON() unexpectedly when split hugepage:
------------[ cut here ]------------
kernel BUG at mm/page_table_check.c:119!
Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:
CPU: 7 PID: 210 Comm: transhuge-stres Not tainted 6.1.0-rc3+ #748
Hardware name: linux,dummy-virt (DT)
pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : page_table_check_set.isra.0+0x398/0x468
lr : page_table_check_set.isra.0+0x1c0/0x468
[...]
Call trace:
page_table_check_set.isra.0+0x398/0x468
__page_table_check_pte_set+0x160/0x1c0
__split_huge_pmd_locked+0x900/0x1648
__split_huge_pmd+0x28c/0x3b8
unmap_page_range+0x428/0x858
unmap_single_vma+0xf4/0x1c8
zap_page_range+0x2b0/0x410
madvise_vma_behavior+0xc44/0xe78
do_madvise+0x280/0x698
__arm64_sys_madvise+0x90/0xe8
invoke_syscall.constprop.0+0xdc/0x1d8
do_el0_svc+0xf4/0x3f8
el0_svc+0x58/0x120
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x19c/0x1a0
[...]
On arm64, pmd_leaf() will return true even if the pmd is invalid due to
pmd_present_invalid() check. So in pmdp_invalidate() the file_map_count
will not only decrease once but also increase once. Then in set_pte_at(),
the file_map_count increase again, and so trigger BUG_ON() unexpectedly.
Add !pmd_present_invalid() check in pmd_user_accessible_page() to fix the
problem.
Fixes: 42b2547137f5 ("arm64/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK")
Reported-by: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Signed-off-by: Liu Shixin <liushixin2@xxxxxxxxxx>
Acked-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Acked-by: Will Deacon <will@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20221121073608.4183459-1-liushixin2@xxxxxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/pgtable.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -863,7 +863,7 @@ static inline bool pte_user_accessible_p
static inline bool pmd_user_accessible_page(pmd_t pmd)
{
- return pmd_leaf(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
+ return pmd_leaf(pmd) && !pmd_present_invalid(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
}
static inline bool pud_user_accessible_page(pud_t pud)
