From: Oleg Nesterov <oleg@tv-sign.ru>
Date: Sat, 18 Mar 2006 17:41:10 +0000 (+0300)
Subject: [PATCH] disable unshare(CLONE_VM) for now
X-Git-Tag: v2.6.16~7
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2d61b86775a5676a8fba2ba2f0f869564e35c630;p=linux-2.6

[PATCH] disable unshare(CLONE_VM) for now

sys_unshare() does mmput(new_mm).  This is not enough if we have
mm->core_waiters.

This patch is a temporary fix for soon to be released 2.6.16.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
[ Checked with Uli: "I'm not planning to use unshare(CLONE_VM).  It's
  not needed for any functionality planned so far.  What we (as in Red
  Hat) need unshare() for now is the filesystem side." ]
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/kernel/fork.c b/kernel/fork.c
index 46060cb24a..b373322ca4 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1478,9 +1478,7 @@ static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp)
 
 	if ((unshare_flags & CLONE_VM) &&
 	    (mm && atomic_read(&mm->mm_users) > 1)) {
-		*new_mmp = dup_mm(current);
-		if (!*new_mmp)
-			return -ENOMEM;
+		return -EINVAL;
 	}
 
 	return 0;