@@ -431,7 +431,7 @@ static void insert_to_mm_slots_hash(stru
static inline int khugepaged_test_exit(struct mm_struct *mm)
{
- return atomic_read(&mm->mm_users) == 0;
+ return atomic_read(&mm->mm_users) == 0 || !mmget_still_valid(mm);
}
static bool hugepage_vma_check(struct vm_area_struct *vma,
@@ -1100,9 +1100,6 @@ static void collapse_huge_page(struct mm
* handled by the anon_vma lock + PG_lock.
*/
mmap_write_lock(mm);
- result = SCAN_ANY_PROCESS;
- if (!mmget_still_valid(mm))
- goto out;
result = hugepage_vma_revalidate(mm, address, &vma);
if (result)
goto out;
The patch titled Subject: khugepaged: khugepaged_test_exit() check mmget_still_valid() has been added to the -mm tree. Its filename is khugepaged-khugepaged_test_exit-check-mmget_still_valid.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/khugepaged-khugepaged_test_exit-check-mmget_still_valid.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/khugepaged-khugepaged_test_exit-check-mmget_still_valid.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Hugh Dickins <hughd@google.com> Subject: khugepaged: khugepaged_test_exit() check mmget_still_valid() Move collapse_huge_page()'s mmget_still_valid() check into khugepaged_test_exit() itself. collapse_huge_page() is used for anon THP only, and earned its mmget_still_valid() check because it inserts a huge pmd entry in place of the page table's pmd entry; whereas collapse_file()'s retract_page_tables() or collapse_pte_mapped_thp() merely clears the page table's pmd entry. But core dumping without mmap lock must have been as open to mistaking a racily cleared pmd entry for a page table at physical page 0, as exit_mmap() was. And we certainly have no interest in mapping as a THP once dumping core. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008021217020.27773@eggly.anvils Fixes: 59ea6d06cfa9 ("coredump: fix race condition between collapse_huge_page() and core dumping") Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Song Liu <songliubraving@fb.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- mm/khugepaged.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)