linux-kernel - Re: [RFC Patch 2/2] mm: Add parameters to limit a rate of outputting memory error messages

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Message-ID: <1365691626-w2h428s2-mutt-n-horiguchi@ah.jp.nec.com>
Date:	Thu, 11 Apr 2013 10:47:06 -0400
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Mitsuhiro Tanino <mitsuhiro.tanino.gm@...achi.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>
Subject: Re: [RFC Patch 2/2] mm: Add parameters to limit a rate of outputting
 memory error messages

On Thu, Apr 11, 2013 at 04:00:12PM +0200, Andi Kleen wrote:
> > 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.
> 
> Note that when you really have a flood of uncorrected errors you'll
> likely die soon anyways as something unrecoverable is very likely to
> happen. Error memory recovery cannot fix large scale memory corruptions,
> just the rare events that slip through all the other memory error correction
> schemes.
> 
> So I wouldn't worry too much about that.

I agree.
My previous comment is valid only when we assume the flooding can happen
(and I personally don't believe that can happen except for in testing.)

And for paranoid users, we can suggest that they set up mcelog script
triggering to turn off vm.memory_failure_recovery when memory errors flood.
Such users don't expect that memory error handling works fine in flooding,
so just suppressing kernel messages is pointless.

Thanks,
Naoya
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