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Re: [patch] thread-aware coredumps, 2.5.43-C3



On Thu, Oct 17, 2002 at 11:11:21AM +0200, Ingo Molnar wrote:
> - properly wait for all threads that share the same MM to serialize with
>   the coredumping thread. This is CLONE_VM based, not tied to
>   CLONE_THREAD and/or signal semantics, ie. old-style (or different-style)
>   threaded apps will be properly stopped as well.
> 
>   The locking might look a bit complex, but i wanted to keep the
>   __exit_mm() overhead as low as possible. It's not quite trivial to get
>   these bits right, because 'sharing the MM' is detached from signals
>   semantics, so we cannot rely on broadcast-kill catching all threads. So
>   zap_threads() iterates through every thread and zaps those which were
>   left out. (There's a minimal race left in where a newly forked child
>   might escape the attention of zap_threads() - this race is fixed by the
>   OOM fixes in the mmap-speedup patch.)

My only problem with this is that you're waiting for all threads by
SIGKILLing them.  If a process vforks or clones, and then the child
crashes, the parent will receive a SIGKILL - iff we are dumping core. 
That's a change in behavior that seems a bit too arbitrary to me.


-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer





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