[PATCH] swapoff: use atomic_inc_not_zero() on mm_users (70af7c5c) · Commits · 戴 / test

Now that we have atomic_inc_not_zero, it's more elegant for try_to_unuse to use that on mm_users: doesn't actually matter at present, but safer to be sure that once mm_users has gone to 0, nothing raises it for an instant. Signed-off-by:

Hugh Dickins <hugh@veritas.com> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

mm/swapfile.c

+1 −3

Original line number	Original line	Diff line number	Diff line
	@@ -772,10 +772,8 @@ static int try_to_unuse(unsigned int type)
	while (*swap_map > 1 && !retval &&		while (*swap_map > 1 && !retval &&
	(p = p->next) != &start_mm->mmlist) {		(p = p->next) != &start_mm->mmlist) {
	mm = list_entry(p, struct mm_struct, mmlist);		mm = list_entry(p, struct mm_struct, mmlist);
	if (atomic_inc_return(&mm->mm_users) == 1) {		if (!atomic_inc_not_zero(&mm->mm_users))
	atomic_dec(&mm->mm_users);
	continue;		continue;
	}
	spin_unlock(&mmlist_lock);		spin_unlock(&mmlist_lock);
	mmput(prev_mm);		mmput(prev_mm);
	prev_mm = mm;		prev_mm = mm;

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