linux-kernel - Re: [patch] vmscan: print shrink_slab symbol name on negative shrinker objects

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Date:	Fri, 20 Mar 2009 03:15:41 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: [patch] vmscan: print shrink_slab symbol name on negative shrinker
 objects

On Thu, 19 Mar 2009, Andrew Morton wrote:

> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -40,6 +40,7 @@
> >  #include <linux/memcontrol.h>
> >  #include <linux/delayacct.h>
> >  #include <linux/sysctl.h>
> > +#include <linux/kallsyms.h>
> >  
> >  #include <asm/tlbflush.h>
> >  #include <asm/div64.h>
> > @@ -214,8 +215,12 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
> >  		do_div(delta, lru_pages + 1);
> >  		shrinker->nr += delta;
> >  		if (shrinker->nr < 0) {
> > -			printk(KERN_ERR "%s: nr=%ld\n",
> > -					__func__, shrinker->nr);
> > +			char symname[KSYM_NAME_LEN];
> > +
> > +			if (lookup_symbol_name((unsigned long)shrinker->shrink,
> > +					       symname) > 0)
> > +				printk(KERN_ERR "shrink_slab: %s nr=%ld\n",
> > +				       symname, shrinker->nr);
> >  			shrinker->nr = max_pass;
> >  		}
> 
> Can we use the new printk("%pF", ...) here?
> 

Cool, that's super convenient.


vmscan: print shrink_slab symbol name on negative shrinker objects

When a shrinker has a negative number of objects to delete, the symbol
name of the shrinker should be printed, not shrink_slab.  This also makes
the error message slightly more informative.

Cc: Ingo Molnar <mingo@...e.hu>
Signed-off-by: David Rientjes <rientjes@...gle.com>
---
 mm/vmscan.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -214,8 +214,9 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
 		do_div(delta, lru_pages + 1);
 		shrinker->nr += delta;
 		if (shrinker->nr < 0) {
-			printk(KERN_ERR "%s: nr=%ld\n",
-					__func__, shrinker->nr);
+			printk(KERN_ERR "shrink_slab: %pF negative objects to "
+			       "delete nr=%ld\n",
+			       shrinker->shrink, shrinker->nr);
 			shrinker->nr = max_pass;
 		}
 
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