Re: mainline boot failures I: qemu

[Al Viro <viro@ZenIV.linux.org.uk>]

On Sat, Apr 26, 2008 at 04:02:10PM +0200, Andi Kleen wrote:
> 
> FYI
> 
> I see lots of boot failures on various setups with current mainline
> (git8, b1721d0da266b4af8cb4419473b4ca36206ab200). Unfortunately 
> they are all different. 

See http://lkml.org/lkml/2008/4/26/1

FWIW, I've reconstructed what had happened:
	* broken changeset in local tree
	* breakage caught, fixed (still in local tree)
	* cherry-pick into new branch in local tree, fix folded
	* *old* changeset taken into the public tree
	* a couple of days later Linus asked to pull
	* pull from Linus' tree into local triggering conflict
	* what the... oh, hell.

Again, the missing bit is this, see if it fixes all of the breakage
you see.  It's a memory corruptor that got immediately caught in
testing, of course - most of the boots don't even get past exec
of /sbin/init.

Brown paperbag time ;-/

diff --git a/kernel/fork.c b/kernel/fork.c
index 4df3949..a647542 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1788,7 +1788,7 @@ bad_unshare_out:
 int unshare_files(struct files_struct **displaced)
 {
 	struct task_struct *task = current;
-	struct files_struct *copy;
+	struct files_struct *copy = NULL;
 	int error;
 
 	error = unshare_fd(CLONE_FILES, &copy);