Messages in this thread | | | Date | Wed, 9 May 2012 23:05:51 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 1/3] coredump: flush the fpu exit state for proper multi-threaded core dump |
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On 05/08, Suresh Siddha wrote: > > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -656,6 +656,11 @@ static void exit_mm(struct task_struct * tsk) > struct core_thread self; > up_read(&mm->mmap_sem); > > + /* > + * Flush the live extended register state to memory. > + */ > + prepare_to_copy(tsk);
This doesn't look very nice imho, but I guess you understand this...
Perhaps we need an arch-dependent helper which saves the FPU regs if needed.
I can be easily wrong, but I did the quick grep and I am not sure we can rely on prepare_to_copy(). For example, it is a nop in arch/sh/include/asm/processor_64.h. But at the same time it has save_fpu().
OTOH, I am not sure it is safe to use prepare_to_copy() in exit_mm(), at least in theory. God knows what it can do...
But again, I do not think I can comment this change. Perhaps this is the right step anyway.
Oleg.
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