Re: [BUG] running strace utility can cause system to hang at sys_ptrace

From: Christoph Hellwig <hch_at_infradead.org>
Date: 2006-07-14 04:45:59
On Thu, Jul 13, 2006 at 11:24:40AM -0700, Jay Lan wrote:
> >We ran into a system hang problem at sys_ptrace.
> >
> >The system may hang if a user attempts to "strace" a pthreaded
> >application that is making frequent calls to pthread_create &
> >pthread_exit.
> >The hang is caused by a task sleeping (yield()) while holding the
> >tasklist_lock.
> >
> >Note that the problem appears to exist ONLY on IA64. IA64 has an
> >ARCH-specific implementation of sys_ptrace().

And David's patch to get rid of this ia64-special would fix this aswell:

http://marc.theaimsgroup.com/?l=linux-kernel&m=111575781225495&w=2

Note that this patch would need some updates for merging these days:

 - make ptrace_attach_sync_user_rbs and architecture hook aswell, so
   that ia64 can use the generic ptrace code
 - kmalloc return value needs checking
 - adjust coding style to match the normal linux style now that
   arch/ia64/ adheres to it.

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Received on Fri Jul 14 04:46:37 2006

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