[libvirt] [PATCH] LXC: make sure fuse thread start to run before we do clone

Daniel P. Berrange berrange at redhat.com
Fri Nov 8 05:30:09 UTC 2013


On Thu, Nov 07, 2013 at 09:15:43PM +0800, Gao feng wrote:
> I met a problem that container blocked by seteuid/setegid
> which is call in lxcContainerSetID on UP system and libvirt
> compiled with --with-fuse=yes.
> 
> I looked into the glibc's codes, and found setxid in glibc
> calls futex() to wait for other threads to change their
> setxid_futex to 0(see setxid_mark_thread in glibc).
> 
> since the process created by clone system call will not
> share the memory with the other threads and the context
> of memory doesn't changed until we call execl.(COW)
> 
> So if the process which created by clone is called before
> fuse thread being stated, the new setxid_futex of fuse
> thread will not be saw in this process, it will be blocked
> forever.
> 
> Maybe this problem should be fixed in glibc, but I send
> this patch as a quick fix.

Can you show a stack trace of the threads/processes deadlocking


Daniel
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