On Tue, 2007-07-31 at 11:31 +0200, Pavel Machek wrote:
> Hi!
>
> >
> > During VM oom condition, kill all threads in process group.
> >
> > We have had complaints where a threaded application is left in a bad
> > state after one of it's threads is killed when we hit a VM: out_of_memory
> > condition.
> > Killing just one of the process threads can leave the application in a
> > bad state, whereas killing the entire process group would allow for
> > the application to restart, or be otherwise handled, and makes it very
> > obvious that something has gone wrong.
> >
> > This change allows the entire process group to be taken down, rather
> > than just the one thread.
> >
> > Signed-off-by: Will Schmidt <[email protected]>
>
> > diff --git a/arch/sparc64/mm/fault.c b/arch/sparc64/mm/fault.c
> > index 17123e9..13fdfa3 100644
> > --- a/arch/sparc64/mm/fault.c
> > +++ b/arch/sparc64/mm/fault.c
> > @@ -466,7 +466,7 @@ out_of_memory:
> > up_read(&mm->mmap_sem);
> > printk("VM: killing process %s\n", current->comm);
> > if (!(regs->tstate & TSTATE_PRIV))
> > - do_exit(SIGKILL);
> > + do_group_exit(SIGKILL);
> > goto handle_kernel_fault;
> >
> > intr_or_no_mm:
>
> is the printk still accurate (does it kill more than one process now)?
I was going to double-check this morning.. but don't see where
current->comm is copied into a new task_struct. I thought that all
processes within the group had the same current->comm value, so figure
this is OK.
> Why does it print when it will not really kill the process?
no idea..
> I see similar code across all the archs... would it make sense to
> create common helper... or is the helper too trivial?
The checks blocking flow into do_group_exit, like (regs->tstate &
TSTATE_PRIV) for sparc64, or (user_mode(regs)) for powerpc, do vary
across the arch's. The code could be rearranged to have a helper
containing just the printk and the do_group_exit() call; but I'm not
sure that would be an improvement.
maybe a do_group_sigkill_if(condition); helper :-)
-Will
> Pavel
-
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