On Thu, Apr 11, 2013 at 12:59:38AM -0400, Naoya Horiguchi wrote:
> Hi Tanino-san,
> 
> On Thu, Apr 11, 2013 at 12:27:15PM +0900, Mitsuhiro Tanino wrote:
> > This patch introduces new sysctl interfaces in order to limit
> > a rate of outputting memory error messages.
> > 
> > - vm.memory_failure_print_ratelimit:
> >   Specify the minimum length of time between messages.
> >   By default the rate limiting is disabled.
> > 
> > - vm.memory_failure_print_ratelimit_burst:
> >   Specify the number of messages we can send before rate limiting.
> > 
> > Signed-off-by: Mitsuhiro Tanino <[email protected]>
...
> > @@ -78,6 +79,16 @@ EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);
> >  EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);
> >  EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);
> >  
> > +/*
> > + * This enforces a rate limit for outputting error message.
> > + * The default interval is set to "0" HZ. This means that
> > + * outputting error message is not limited by default.
> > + * The default burst is set to "10". This parameter can control
> > + * to output number of messages per interval.
> > + * If interval is set to "0", the burst is ineffective.
> > + */
> > +DEFINE_RATELIMIT_STATE(sysctl_memory_failure_print_ratelimit, 0 * HZ, 10);
> > +
> >  static int hwpoison_filter_dev(struct page *p)
> >  {
> >     struct address_space *mapping;
> > @@ -622,13 +633,16 @@ static int me_pagecache_dirty(struct page *p, 
> > unsigned long pfn)
> >     SetPageError(p);
> >     if (mapping) {
> >             /* Print more information about the file. */
> > -           if (mapping->host != NULL && S_ISREG(mapping->host->i_mode))
> > -                   pr_info("MCE %#lx: File was corrupted: Dev:%s Inode:%lu 
> > Offset:%lu\n",
> > -                           page_to_pfn(p), mapping->host->i_sb->s_id,
> > -                           mapping->host->i_ino, page_index(p));
> > -           else
> > -                   pr_info("MCE %#lx: A dirty page cache was corrupted.\n",
> > -                           page_to_pfn(p));
> > +           if (__ratelimit(&sysctl_memory_failure_print_ratelimit)) {
> > +                   if (mapping->host != NULL &&
> > +                       S_ISREG(mapping->host->i_mode))
> > +                           pr_info("MCE %#lx: File was corrupted: Dev:%s 
> > Inode:%lu Offset:%lu\n",
> > +                              page_to_pfn(p), mapping->host->i_sb->s_id,
> > +                              mapping->host->i_ino, page_index(p));
> > +                   else
> > +                           pr_info("MCE %#lx: A dirty page cache was 
> > corrupted.\n",
> > +                                   page_to_pfn(p));
> > +           }
> >  
> >             /*
> >              * IO error will be reported by write(), fsync(), etc.

I don't think it's enough to do ratelimit only for me_pagecache_dirty().
When tons of memory errors flood, all of printk()s in memory error handler
can print out tons of messages.

Thanks,
Naoya
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