linux-kernel - Re: futex strangeness in 2.6.23-mm1/UML

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Date:	Tue, 23 Oct 2007 12:55:44 +0400
From:	Pavel Emelyanov <xemul@...nvz.org>
To:	Miklos Szeredi <miklos@...redi.hu>, riel@...hat.com
CC:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	xemul@...nvz.org, raven@...maw.net
Subject: Re: futex strangeness in 2.6.23-mm1/UML

Miklos Szeredi wrote:
>> I guess we can debug it in the old-fashioned ways.  The first of which is
>> to palm the problem off on Pavel ;)

I look at the 2.6.23-mm1 and see that there's one hunk lost. This
is the one Oleg re-sent some days ago (the mail thread subject was
2.6.23-mm1 thread exit_group issue). Here it is (sent 13 oct 2007):

--- kernel/fork.c~	2007-10-13 15:41:35.000000000 +0400
+++ kernel/fork.c	2007-10-13 15:41:41.000000000 +0400
@@ -1443,6 +1443,9 @@ long do_fork(unsigned long clone_flags,
 			task_pid_nr_ns(p, current->nsproxy->pid_ns) :
 				task_pid_vnr(p);
 
+		if (clone_flags & CLONE_PARENT_SETTID)
+			put_user(nr, parent_tidptr);
+
 		if (clone_flags & CLONE_VFORK) {
 			p->vfork_done = &vfork;
 			init_completion(&vfork);

Please, try with this patch.

>> I don't recall seeing a simple step-by-step way by which others can
>> reproduce this?
> 
> My method is this:
> 
> - enable CONFIG_FUSE_FS
> - compile fuse from CVS:
>  cvs -d:pserver:anonymous@...e.cvs.sourceforge.net:/cvsroot/fuse co -P fuse
>  cd fuse
>  ./makeconf.sh
>  ./configure
>  make
>  make -C test
> 
> - in one shell:
>  mkdir /tmp/fuse
>  example/fusexmp_fh -d /tmp/fuse
> 
> - in another shell:
>  mkdir /tmp/test
>  test/test /tmp/fuse/tmp/test
> 
> The result is normally a completed run with "1 tests failed".  On
> 2.6.23-mm1, it just hangs after the first test.
> 
> I've only tried under UML, but since Rick is seeing it on real HW, I
> guess this method may work there as well.
> 
> Miklos
> -
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