Re: [PATCH] multithreaded coredumps for elf exeecutables for O(1)

[Manfred Spraul]

Have you checked that your patch doesn't deadlock on ia64?

> +       /* First pause all related threaded processes */
> +       if (dump_threads)       {
> +               suspend_threads();
> +       }
> +       
> +       /* now stop all vm operations */
> +       down_write(&current->mm->mmap_sem);
> +       segs = current->mm->map_count;
> +
Stopping all vm operations means that copy_{to,from}_user can cause
deadlocks.
ia64 needs copy_to_user in their stack unwind handler, IIRC called by
ELF_CORE_COPY_REGS.

Afaics you don't handle that. You must dump all thread state before
down_write(mmap_sem). And I don't see how you protect against 2 threads
of one process calling suspend_threads() simultaneously.

--
	Manfred