diff options
| author | Baolin Wang <baolin.wang@linux.alibaba.com> | 2022-05-09 18:20:52 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2022-05-13 07:20:07 -0700 |
| commit | 3d0b95cd87b26b0b10e0cda8ee6105c2194a5800 (patch) | |
| tree | 86532f8f27b7791c9157a1359a8707b2da7f320d /mm/hugetlb.c | |
| parent | 6366238b8dfc383723c211c1ffe8c8d7914107e5 (diff) | |
mm: hugetlb: considering PMD sharing when flushing cache/TLBs
This patchset fixes some cache flushing issues if PMD sharing is possible
for hugetlb pages, which were found by code inspection. Meanwhile Mike
found the flush_cache_page() can not cover the whole size of a hugetlb
page on some architectures [1], so I added a new patch 3 to fix this
issue, since I found only try_to_unmap_one() and try_to_migrate_one() need
to fix after some investigation.
[1] https://lore.kernel.org/linux-mm/064da3bb-5b4b-7332-a722-c5a541128705@oracle.com/
This patch (of 3):
When moving hugetlb page tables, the cache flushing is called in
move_page_tables() without considering the shared PMDs, which may be cause
cache issues on some architectures.
Thus we should move the hugetlb cache flushing into
move_hugetlb_page_tables() with considering the shared PMDs ranges,
calculated by adjust_range_if_pmd_sharing_possible(). Meanwhile also
expanding the TLBs flushing range in case of shared PMDs.
Note this is discovered via code inspection, and did not meet a real
problem in practice so far.
Link: https://lkml.kernel.org/r/cover.1651056365.git.baolin.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/0443c8cf20db554d3ff4b439b30e0ff26c0181dd.1651056365.git.baolin.wang@linux.alibaba.com
Fixes: 550a7d60bd5e ("mm, hugepages: add mremap() support for hugepage backed vma")
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Mina Almasry <almasrymina@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 4454c42a82f0..fc31a8f49067 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4922,10 +4922,17 @@ int move_hugetlb_page_tables(struct vm_area_struct *vma, unsigned long old_addr_copy; pte_t *src_pte, *dst_pte; struct mmu_notifier_range range; + bool shared_pmd = false; mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, old_addr, old_end); adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end); + /* + * In case of shared PMDs, we should cover the maximum possible + * range. + */ + flush_cache_range(vma, range.start, range.end); + mmu_notifier_invalidate_range_start(&range); /* Prevent race with file truncation */ i_mmap_lock_write(mapping); @@ -4942,8 +4949,10 @@ int move_hugetlb_page_tables(struct vm_area_struct *vma, */ old_addr_copy = old_addr; - if (huge_pmd_unshare(mm, vma, &old_addr_copy, src_pte)) + if (huge_pmd_unshare(mm, vma, &old_addr_copy, src_pte)) { + shared_pmd = true; continue; + } dst_pte = huge_pte_alloc(mm, new_vma, new_addr, sz); if (!dst_pte) @@ -4951,7 +4960,11 @@ int move_hugetlb_page_tables(struct vm_area_struct *vma, move_huge_pte(vma, old_addr, new_addr, src_pte, dst_pte); } - flush_tlb_range(vma, old_end - len, old_end); + + if (shared_pmd) + flush_tlb_range(vma, range.start, range.end); + else + flush_tlb_range(vma, old_end - len, old_end); mmu_notifier_invalidate_range_end(&range); i_mmap_unlock_write(mapping); |