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authorHugh Dickins <hugh@veritas.com>2005-10-29 18:16:33 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-10-29 21:40:41 -0700
commitdeceb6cd17e6dfafe4c4f81b1b4153bc41b2cb70 (patch)
tree2a722f50e8edef8609a49f65bfcb222e499c44cc /kernel/futex.c
parentc34d1b4d165c67b966bca4aba026443d7ff161eb (diff)
downloadblackbird-op-linux-deceb6cd17e6dfafe4c4f81b1b4153bc41b2cb70.tar.gz
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[PATCH] mm: follow_page with inner ptlock
Final step in pushing down common core's page_table_lock. follow_page no longer wants caller to hold page_table_lock, uses pte_offset_map_lock itself; and so no page_table_lock is taken in get_user_pages itself. But get_user_pages (and get_futex_key) do then need follow_page to pin the page for them: take Daniel's suggestion of bitflags to follow_page. Need one for WRITE, another for TOUCH (it was the accessed flag before: vanished along with check_user_page_readable, but surely get_numa_maps is wrong to mark every page it finds as accessed), another for GET. And another, ANON to dispose of untouched_anonymous_page: it seems silly for that to descend a second time, let follow_page observe if there was no page table and return ZERO_PAGE if so. Fix minor bug in that: check VM_LOCKED - make_pages_present ought to make readonly anonymous present. Give get_numa_maps a cond_resched while we're there. 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/futex.c')
-rw-r--r--kernel/futex.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index ca05fe6a70b2..3b4d5ad44cc6 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -205,15 +205,13 @@ static int get_futex_key(unsigned long uaddr, union futex_key *key)
/*
* Do a quick atomic lookup first - this is the fastpath.
*/
- spin_lock(&current->mm->page_table_lock);
- page = follow_page(mm, uaddr, 0);
+ page = follow_page(mm, uaddr, FOLL_TOUCH|FOLL_GET);
if (likely(page != NULL)) {
key->shared.pgoff =
page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
- spin_unlock(&current->mm->page_table_lock);
+ put_page(page);
return 0;
}
- spin_unlock(&current->mm->page_table_lock);
/*
* Do it the general way.
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