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Date: Fri, 24 Nov 2000 23:28:44 +1100
From: Andrew Morton <andrewm@uow.edu.au>
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To: Mark Ellis <mark.uzumati@virgin.net>
CC: linux-kernel@vger.kernel.org, Alexander Viro <viro@math.psu.edu>
Subject: Re: OOPS on bringing down ppp
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Mark Ellis wrote:
> 
> Hi all, consistently getting the following when pppd is terminated.

When pppd downs the ppp0 device, unregister_netdevice() is
trying to run /sbin/hotplug in a new kernel thread.  That
thread's `files' structure is copied from pppd, but it is
NULL.  Presumably pppd's files pointer was also NULL.

Try this:

--- linux-2.4.0-test11-ac2/kernel/kmod.c	Tue Nov 21 20:11:21 2000
+++ linux-akpm/kernel/kmod.c	Fri Nov 24 23:03:34 2000
@@ -99,8 +99,10 @@
 	flush_signal_handlers(current);
 	spin_unlock_irq(&current->sigmask_lock);
 
-	for (i = 0; i < current->files->max_fds; i++ ) {
-		if (current->files->fd[i]) close(i);
+	if (current->files) {
+		for (i = 0; i < current->files->max_fds; i++ ) {
+			if (current->files->fd[i]) close(i);
+		}
 	}
 
 	/* Drop the "current user" thing */


Not my area, but I don't think exec_usermodehelper() should assume
that current->files is always valid.

Al, is this correct?  If so, does daemonize() also need this test?
If not, then how did this thread get (current->files == NULL)?
-
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