diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2013-12-12 17:12:33 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-12-12 18:19:26 -0800 |
| commit | 3592806cfa08b7cca968f793c33f8e9460bab395 (patch) | |
| tree | fb988d60d644cf5b561fff0866e2ee5632874b36 /mm/huge_memory.c | |
| parent | 3e1e4a5f3a324502c27c4e8808e06ac2ea842360 (diff) | |
thp: move preallocated PTE page table on move_huge_pmd()
Andrey Wagin reported crash on VM_BUG_ON() in pgtable_pmd_page_dtor() with
fallowing backtrace:
free_pgd_range+0x2bf/0x410
free_pgtables+0xce/0x120
unmap_region+0xe0/0x120
do_munmap+0x249/0x360
move_vma+0x144/0x270
SyS_mremap+0x3b9/0x510
system_call_fastpath+0x16/0x1b
The crash can be reproduce with this test case:
#define _GNU_SOURCE
#include <sys/mman.h>
#include <stdio.h>
#include <unistd.h>
#define MB (1024 * 1024UL)
#define GB (1024 * MB)
int main(int argc, char **argv)
{
char *p;
int i;
p = mmap((void *) GB, 10 * MB, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
for (i = 0; i < 10 * MB; i += 4096)
p[i] = 1;
mremap(p, 10 * MB, 10 * MB, MREMAP_FIXED | MREMAP_MAYMOVE, 2 * GB);
return 0;
}
Due to split PMD lock, we now store preallocated PTE tables for THP
pages per-PMD table. It means we need to move them to other PMD table
if huge PMD moved there.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Andrey Vagin <avagin@openvz.org>
Tested-by: Andrey Vagin <avagin@openvz.org>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index bccd5a628ea..33a5dc49281 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1481,8 +1481,18 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, pmd = pmdp_get_and_clear(mm, old_addr, old_pmd); VM_BUG_ON(!pmd_none(*new_pmd)); set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); - if (new_ptl != old_ptl) + if (new_ptl != old_ptl) { + pgtable_t pgtable; + + /* + * Move preallocated PTE page table if new_pmd is on + * different PMD page table. + */ + pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); + pgtable_trans_huge_deposit(mm, new_pmd, pgtable); + spin_unlock(new_ptl); + } spin_unlock(old_ptl); } out: |