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| author | David S. Miller <davem@davemloft.net> | 2017-01-28 10:33:06 -0500 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-01-28 10:33:06 -0500 |
| commit | 4e8f2fc1a55d543717efb70e170b09e773d0542b (patch) | |
| tree | 30df1d7fc9dfa24fe2916711a17656682c3f7ec9 /mm/huge_memory.c | |
| parent | 158f323b9868b59967ad96957c4ca388161be321 (diff) | |
| parent | 1b1bc42c1692e9b62756323c675a44cb1a1f9dbd (diff) | |
| download | linux-4e8f2fc1a55d543717efb70e170b09e773d0542b.tar.bz2 | |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Two trivial overlapping changes conflicts in MPLS and mlx5.
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 9a6bd6c8d55a..5f3ad65c85de 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -783,6 +783,12 @@ struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, assert_spin_locked(pmd_lockptr(mm, pmd)); + /* + * When we COW a devmap PMD entry, we split it into PTEs, so we should + * not be in this function with `flags & FOLL_COW` set. + */ + WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); + if (flags & FOLL_WRITE && !pmd_write(*pmd)) return NULL; @@ -1128,6 +1134,16 @@ out_unlock: return ret; } +/* + * FOLL_FORCE can write to even unwritable pmd's, but only + * after we've gone through a COW cycle and they are dirty. + */ +static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) +{ + return pmd_write(pmd) || + ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); +} + struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, unsigned long addr, pmd_t *pmd, @@ -1138,7 +1154,7 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, assert_spin_locked(pmd_lockptr(mm, pmd)); - if (flags & FOLL_WRITE && !pmd_write(*pmd)) + if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) goto out; /* Avoid dumping huge zero page */ |