diff options
| author | Zach O'Keefe <zokeefe@google.com> | 2022-09-22 15:27:31 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2022-10-03 14:03:32 -0700 |
| commit | 780a4b6fb865534fcb3aa9150942f3a719d11ce9 (patch) | |
| tree | 14c69ce8e03be4fd439e8393414aaee698362ccd | |
| parent | 958f32ce832ba781ac20e11bb2d12a9352ea28fc (diff) | |
mm/khugepaged: check compound_order() in collapse_pte_mapped_thp()
By the time we lock a page in collapse_pte_mapped_thp(), the page mapped
by the address pushed onto the slot's .pte_mapped_thp[] array might have
changed arbitrarily since we last looked at it. We revalidate that the
page is still the head of a compound page, but we don't revalidate if the
compound page is of order HPAGE_PMD_ORDER before applying rmap and page
table updates.
Since the kernel now supports large folios of arbitrary order, and since
replacing page's pte mappings by a pmd mapping only makes sense for
compound pages of order HPAGE_PMD_ORDER, revalidate that the compound
order is indeed of order HPAGE_PMD_ORDER before proceeding.
Link: https://lore.kernel.org/linux-mm/CAHbLzkon+2ky8v9ywGcsTUgXM_B35jt5NThYqQKXW2YV_GUacw@mail.gmail.com/
Link: https://lkml.kernel.org/r/20220922222731.1124481-1-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Suggested-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/khugepaged.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 57af2c841b41..40fd9f7b3ed3 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1399,6 +1399,9 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) if (!PageHead(hpage)) goto drop_hpage; + if (compound_order(hpage) != HPAGE_PMD_ORDER) + goto drop_hpage; + if (find_pmd_or_thp_or_none(mm, haddr, &pmd) != SCAN_SUCCEED) goto drop_hpage; |