diff options
| author | Miaohe Lin <linmiaohe@huawei.com> | 2021-05-04 18:33:40 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-05-05 11:27:20 -0700 |
| commit | 588d01f918d42d2d453d8cd5af6bf2c2e1072a47 (patch) | |
| tree | 63077971b0e6a5166c1ea3b76f1c477d31298014 /mm/khugepaged.c | |
| parent | 0edf61e5ee5c334f33bb7bf95d1b470f01ae9fec (diff) | |
khugepaged: reuse the smp_wmb() inside __SetPageUptodate()
smp_wmb() is needed to avoid the copy_huge_page writes to become visible
after the set_pmd_at() write here. But we can reuse the smp_wmb() inside
__SetPageUptodate() to remove this redundant one.
Link: https://lkml.kernel.org/r/20210306032947.35921-3-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/khugepaged.c')
| -rw-r--r-- | mm/khugepaged.c | 13 |
1 files changed, 6 insertions, 7 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index d43812c5ce16..287e7ecf978c 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1183,19 +1183,18 @@ static void collapse_huge_page(struct mm_struct *mm, __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl, &compound_pagelist); pte_unmap(pte); + /* + * spin_lock() below is not the equivalent of smp_wmb(), but + * the smp_wmb() inside __SetPageUptodate() can be reused to + * avoid the copy_huge_page writes to become visible after + * the set_pmd_at() write. + */ __SetPageUptodate(new_page); pgtable = pmd_pgtable(_pmd); _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); - /* - * spin_lock() below is not the equivalent of smp_wmb(), so - * this is needed to avoid the copy_huge_page writes to become - * visible after the set_pmd_at() write. - */ - smp_wmb(); - spin_lock(pmd_ptl); BUG_ON(!pmd_none(*pmd)); page_add_new_anon_rmap(new_page, vma, address, true); |