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| author | Hugh Dickins <hugh@veritas.com> | 2005-10-29 18:16:23 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-10-29 21:40:40 -0700 |
| commit | c74df32c724a1652ad8399b4891bb02c9d43743a (patch) | |
| tree | 5a79d56fdcf7dc2053a277dbf6db7c3b339e9659 /kernel/fork.c | |
| parent | 1bb3630e89cb8a7b3d3807629c20c5bad88290ff (diff) | |
| download | linux-c74df32c724a1652ad8399b4891bb02c9d43743a.tar.gz linux-c74df32c724a1652ad8399b4891bb02c9d43743a.tar.bz2 linux-c74df32c724a1652ad8399b4891bb02c9d43743a.zip | |
[PATCH] mm: ptd_alloc take ptlock
Second step in pushing down the page_table_lock. Remove the temporary
bridging hack from __pud_alloc, __pmd_alloc, __pte_alloc: expect callers not
to hold page_table_lock, whether it's on init_mm or a user mm; take
page_table_lock internally to check if a racing task already allocated.
Convert their callers from common code. But avoid coming back to change them
again later: instead of moving the spin_lock(&mm->page_table_lock) down,
switch over to new macros pte_alloc_map_lock and pte_unmap_unlock, which
encapsulate the mapping+locking and unlocking+unmapping together, and in the
end may use alternatives to the mm page_table_lock itself.
These callers all hold mmap_sem (some exclusively, some not), so at no level
can a page table be whipped away from beneath them; and pte_alloc uses the
"atomic" pmd_present to test whether it needs to allocate. It appears that on
all arches we can safely descend without page_table_lock.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 2a587b3224e3..8a069612eac3 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -255,7 +255,6 @@ static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) /* * Link in the new vma and copy the page table entries. */ - spin_lock(&mm->page_table_lock); *pprev = tmp; pprev = &tmp->vm_next; @@ -265,7 +264,6 @@ static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) mm->map_count++; retval = copy_page_range(mm, oldmm, tmp); - spin_unlock(&mm->page_table_lock); if (tmp->vm_ops && tmp->vm_ops->open) tmp->vm_ops->open(tmp); |