Re: [PATCH 0/5] dump_stack: allow specifying printk log level

[Michal Hocko <mhocko@kernel.org>]

On Thu 05-11-15 17:30:14, aris@redhat.com wrote:
> This patchset lays the foundation work to allow using dump_stack() with a
> specified printk log level. Currently each architecture uses a different
> log level in show_stack() and it's not possible to control it without
> calling directly architecture specific functions.
> 
> The motivation behind this work is to limit the amount of kernel messages
> printed in the console when a process is killed by the OOM killer. In some
> scenarios (lots of containers running different customers' workloads) OOMs
> are way more common and don't require the console to be flooded by stack
> traces when the OOM killer probably did the right choice. During a recent
> discussion it was determined that a knob to control when dump_stack() is
> called is a bad idea and instead we should tune the log level in dump_stack()
> which prompted this work.
> 
> This patchset introduces two new functions:
> 	dump_stack_lvl(char *log_lvl)
> 	show_stack_lvl(struct task_struct *task, unsigned long *sp, char *log_lvl)
> 
> and both can be reimplemented by each architecture but only the second is
> expected. The idea is to initially implement show_stack_lvl() in all
> architectures then simply have show_stack() to require log_lvl as parameter.
> While that happens, dump_stack() uses can be changed to dump_stack_lvl() and
> once everything is in place, dump_stack() will require the log_level as well.

This looks good to me FWIW.
 
> I have a draft patch for every architecture but for this patchset I'm only
> including x86 to get some feedback while I try to get a cross compiler working
> for each one of them (which is being harder than I thought).
>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Greg Thelen <gthelen@google.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: David Rientjes <rientjes@google.com>
> Signed-off-by: Aristeu Rozanski <aris@redhat.com>
> 
> -- 
> Aristeu

-- 
Michal Hocko
SUSE Labs

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