All of lore.kernel.org
 help / color / mirror / Atom feed
From: Jens Axboe <axboe@kernel.dk>
To: Anton Ivanov <anton.ivanov@cambridgegreys.com>,
	linux-um@lists.infradead.org
Cc: richard@nod.at, hch@lst.de
Subject: Re: New Patch series for the UBD Driver
Date: Tue, 13 Nov 2018 06:30:53 -0700	[thread overview]
Message-ID: <1d7151d0-62b7-000c-c506-7b321bf788bb@kernel.dk> (raw)
In-Reply-To: <e6df0eee-6446-08b1-42be-ee93c95613cc@cambridgegreys.com>

On 11/13/18 3:15 AM, Anton Ivanov wrote:
> I have figured out part of it. It is not caused by the block layer at 
> all. The offending parts are printks in the io thread. You simply cannot 
> printk out of there, that causes the spinlock recursion, irqs, on/off, 
> etc warning.
> 
> This means that any errors MUST be reported only after they have gone 
> back to the main UML kernel thread.

That's a pretty serious issue with UML, there's absolutely nothing wrong
with doing printk from IRQ context, or from an IO thread like this one.
You don't know what the call stack below you will do for functions you
call, this is a ticking time bomb.

-- 
Jens Axboe


_______________________________________________
linux-um mailing list
linux-um@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-um


  parent reply	other threads:[~2018-11-13 13:31 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-12 17:41 New Patch series for the UBD Driver anton.ivanov
2018-11-12 17:41 ` [PATCH 1/3] um: Switch to block-mq constants in the UML UBD driver anton.ivanov
2018-11-12 17:48   ` Jens Axboe
2018-11-12 17:52     ` Anton Ivanov
2018-11-12 17:42 ` [PATCH 2/3] um: Clean-up command processing in " anton.ivanov
2018-11-12 17:42 ` [PATCH 3/3] um: Add support for DISCARD in the UBD Driver anton.ivanov
2018-11-12 17:50 ` New Patch series for " Jens Axboe
2018-11-12 18:00   ` Anton Ivanov
2018-11-12 18:04     ` Jens Axboe
2018-11-12 18:12       ` Anton Ivanov
2018-11-12 18:14         ` Jens Axboe
2018-11-12 18:23           ` Anton Ivanov
2018-11-12 18:24             ` Anton Ivanov
2018-11-12 18:28             ` Jens Axboe
2018-11-12 18:41               ` Anton Ivanov
2018-11-12 19:11                 ` Jens Axboe
2018-11-12 19:26                   ` Jens Axboe
2018-11-13  8:42                     ` Anton Ivanov
2018-11-13 10:15                       ` Anton Ivanov
2018-11-13 10:20                         ` Anton Ivanov
2018-11-13 13:30                         ` Jens Axboe [this message]
2018-11-13 13:56                           ` Anton Ivanov
2018-11-13 15:14                             ` Jens Axboe
2018-11-13 15:24                               ` Anton Ivanov
2018-11-13 15:29                                 ` Jens Axboe

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1d7151d0-62b7-000c-c506-7b321bf788bb@kernel.dk \
    --to=axboe@kernel.dk \
    --cc=anton.ivanov@cambridgegreys.com \
    --cc=hch@lst.de \
    --cc=linux-um@lists.infradead.org \
    --cc=richard@nod.at \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.