Re: [PATCH v2] Show kernel stack usage to /proc/meminfo and OOM log

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

> On Wed, 1 Jul 2009, KOSAKI Motohiro wrote:
> 
> > Subject: [PATCH] Show kernel stack usage to /proc/meminfo and OOM log
> > 
> > if the system have a lot of thread, kernel stack consume unignorable large size
> > memory.
> > IOW, it make a lot of unaccountable memory.
> > 
> > Tons unaccountable memory bring to harder analyse memory related trouble.
> > 
> > Then, kernel stack account is useful.
> > 
> > 
> 
> I know this is the second revision of the patch, apologies for not 
> responding to the first.

Thanks, good review.

> 
> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> > ---
> >  fs/proc/meminfo.c      |    2 ++
> >  include/linux/mmzone.h |    3 ++-
> >  kernel/fork.c          |   12 ++++++++++++
> >  mm/page_alloc.c        |    6 ++++--
> >  mm/vmstat.c            |    1 +
> >  5 files changed, 21 insertions(+), 3 deletions(-)
> > 
> > Index: b/fs/proc/meminfo.c
> > ===================================================================
> > --- a/fs/proc/meminfo.c
> > +++ b/fs/proc/meminfo.c
> > @@ -85,6 +85,7 @@ static int meminfo_proc_show(struct seq_
> >  		"SReclaimable:   %8lu kB\n"
> >  		"SUnreclaim:     %8lu kB\n"
> >  		"PageTables:     %8lu kB\n"
> > +		"KernelStack     %8lu kB\n"
> 
> Missing :.

Grr, thanks. Will fix.

> 
> >  #ifdef CONFIG_QUICKLIST
> >  		"Quicklists:     %8lu kB\n"
> >  #endif
> > @@ -129,6 +130,7 @@ static int meminfo_proc_show(struct seq_
> >  		K(global_page_state(NR_SLAB_RECLAIMABLE)),
> >  		K(global_page_state(NR_SLAB_UNRECLAIMABLE)),
> >  		K(global_page_state(NR_PAGETABLE)),
> > +		K(global_page_state(NR_KERNEL_STACK)),
> >  #ifdef CONFIG_QUICKLIST
> >  		K(quicklist_total_size()),
> >  #endif
> > Index: b/include/linux/mmzone.h
> > ===================================================================
> > --- a/include/linux/mmzone.h
> > +++ b/include/linux/mmzone.h
> > @@ -94,10 +94,11 @@ enum zone_stat_item {
> >  	NR_SLAB_RECLAIMABLE,
> >  	NR_SLAB_UNRECLAIMABLE,
> >  	NR_PAGETABLE,		/* used for pagetables */
> > +	NR_KERNEL_STACK,
> > +	/* Second 128 byte cacheline */
> >  	NR_UNSTABLE_NFS,	/* NFS unstable pages */
> >  	NR_BOUNCE,
> >  	NR_VMSCAN_WRITE,
> > -	/* Second 128 byte cacheline */
> >  	NR_WRITEBACK_TEMP,	/* Writeback using temporary buffers */
> >  #ifdef CONFIG_NUMA
> >  	NUMA_HIT,		/* allocated in intended node */
> > Index: b/kernel/fork.c
> > ===================================================================
> > --- a/kernel/fork.c
> > +++ b/kernel/fork.c
> > @@ -137,9 +137,18 @@ struct kmem_cache *vm_area_cachep;
> >  /* SLAB cache for mm_struct structures (tsk->mm) */
> >  static struct kmem_cache *mm_cachep;
> >  
> > +static void account_kernel_stack(struct thread_info *ti, int on)
> > +{
> > +	struct zone *zone = page_zone(virt_to_page(ti));
> > +	int pages = THREAD_SIZE / PAGE_SIZE;
> > +
> > +	mod_zone_page_state(zone, NR_KERNEL_STACK, on ? pages : -pages);
> > +}
> > +
> >  void free_task(struct task_struct *tsk)
> >  {
> >  	prop_local_destroy_single(&tsk->dirties);
> > +	account_kernel_stack(tsk->stack, 0);
> 
> I think it would be better to do
> 
> 	#define THREAD_PAGES	(THREAD_SIZE / PAGE_SIZE)
> 
> since it's currently unused and then
> 
> 	struct zone *zone = page_zone(virt_to_page(tsk->stack));
> 	mod_zone_page_state(zone, NR_KERNEL_STACK, THREAD_PAGES);
> 
> in free_task() and
> 
> 	struct zone *zone = page_zone(virt_to_page(ti));
> 	mod_zone_page_state(zone, NR_KERNEL_STACK, -THREAD_PAGES);
> 
> in dup_task_struct().

maybe, gcc makes same code. then I keep current code. because
"struct zone *zone = page_zone(virt_to_page(tsk->stack))" line is a bit 
complicate statement and I don't hope sprinkle it.

> 
> >  	free_thread_info(tsk->stack);
> >  	rt_mutex_debug_task_free(tsk);
> >  	ftrace_graph_exit_task(tsk);
> > @@ -255,6 +264,9 @@ static struct task_struct *dup_task_stru
> >  	tsk->btrace_seq = 0;
> >  #endif
> >  	tsk->splice_pipe = NULL;
> > +
> > +	account_kernel_stack(ti, 1);
> > +
> >  	return tsk;
> >  
> >  out:
> > Index: b/mm/page_alloc.c
> > ===================================================================
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -2119,7 +2119,8 @@ void show_free_areas(void)
> >  		" inactive_file:%lu"
> >  		" unevictable:%lu"
> >  		" dirty:%lu writeback:%lu unstable:%lu\n"
> > -		" free:%lu slab:%lu mapped:%lu pagetables:%lu bounce:%lu\n",
> > +		" free:%lu slab:%lu mapped:%lu pagetables:%lu bounce:%lu\n"
> > +		" kernel_stack:%lu\n",
> 
> Does kernel_stack really need to be printed on its own line?

Well, my another patch (Makes slab pages field in show_free_areas() separate two field)
already used full space of previous line. new line is really needed.





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