From: Theodore Ts'o <tytso@mit.edu>
To: Anatol Pomazau <anatol@google.com>
Cc: linux-ext4@vger.kernel.org, Anatol Pomozov <anatol.pomozov@gmail.com>
Subject: Re: ext4: Rate limit printk in buffer_io_error()
Date: Thu, 11 Jul 2013 22:44:12 -0400 [thread overview]
Message-ID: <20130712024412.GA23785@thunk.org> (raw)
In-Reply-To: <1373410898-26826-1-git-send-email-anatol@google.com>
On Tue, Jul 09, 2013 at 04:01:38PM -0700, Anatol Pomazau wrote:
> From: Anatol Pomozov <anatol.pomozov@gmail.com>
>
> If there are a lot of outstanding buffered IOs when a device is
> taken offline (due to hardware errors etc), ext4_end_bio prints
> out a message for each failed logical block. While this is desirable,
> we see thousands of such lines being printed out before the
> serial console gets overwhelmed, causing ext4_end_bio() wait for
> the printk to complete.
>
> This in itself isn't a disaster, except for the detail that this
> function is being called with the queue lock held.
> This causes any other function in the block layer
> to spin on its spin_lock_irqsave while the serial console is
> draining. If NMI watchdog is enabled on this machine then it
> eventually comes along and shoots the machine in the head.
>
> The end result is that losing any one disk causes the machine to
> go down. This patch rate limits the printk to bandaid around the
> problem.
>
> Tested: xfstests
> Change-Id: I8ab5690dcf4f3a67e78be147d45e489fdf4a88d8
> Signed-off-by: Anatol Pomozov <anatol.pomozov@gmail.com>
Thanks, applied.
- Ted
prev parent reply other threads:[~2013-07-12 2:44 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-09 23:01 [PATCH] ext4: Rate limit printk in buffer_io_error() Anatol Pomazau
2013-07-12 2:44 ` Theodore Ts'o [this message]
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