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author | 2020-08-06 23:26:25 -0700 | |
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committer | 2020-08-07 11:33:29 -0700 | |
commit | bbe98f9cadff58cdd6a4acaeba0efa8565dabe65 (patch) | |
tree | a1a006139ee1f1335ed085830965f9962fd068da /mm/page_isolation.c | |
parent | khugepaged: retract_page_tables() remember to test exit (diff) | |
download | linux-bbe98f9cadff58cdd6a4acaeba0efa8565dabe65.tar.gz linux-bbe98f9cadff58cdd6a4acaeba0efa8565dabe65.tar.bz2 linux-bbe98f9cadff58cdd6a4acaeba0efa8565dabe65.zip |
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.
Fixes: 59ea6d06cfa9 ("coredump: fix race condition between collapse_huge_page() and core dumping")
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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+]
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008021217020.27773@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_isolation.c')
0 files changed, 0 insertions, 0 deletions