All of lore.kernel.org
 help / color / mirror / Atom feed
From: Anton Ivanov <anton.ivanov@kot-begemot.co.uk>
To: Christoph Hellwig <hch@lst.de>, Richard Weinberger <richard@nod.at>
Cc: axboe@kernel.dk, linux-um@lists.infradead.org
Subject: Re: 4.20-rc1 looks broken for UML
Date: Wed, 7 Nov 2018 10:46:05 +0000	[thread overview]
Message-ID: <31d79c23-0fa0-956e-5477-0c326416fc45@kot-begemot.co.uk> (raw)
In-Reply-To: <20181107075318.GA24381@lst.de>

On 11/7/18 7:53 AM, Christoph Hellwig wrote:

> On Tue, Nov 06, 2018 at 09:49:45PM +0100, Richard Weinberger wrote:
>> Christoph,
>>
>> Anton found a problem in your "ubd: remove use of blk_rq_map_sg" patch.
>> With CONFIG_DEBUG_PAGEALLOC enabled, the ubd driver crashes because it tries
>> to deref address 0x12345678, which is the poison from store_stackinfo().
>>
>> Please see below for more info.
>> Can it be that your change introduced a use-after-free bug in UML's block driver?
> Sounds like it.  But I'll need some more time to debug it.

I had to revert 4e6da0fe8058df9bfa937902fcd9cb2b7b89b2df "um: Convert 
ubd driver to blk-mq" as well to get things back to business as usual.

The block-mq driver works for reading - no issues if everything is ro. 
It also clearly works for writing for some configs in older kernels, 
otherwise it would have been picked up.

Something changed in 4.20-rc1 which made it fail in my config. The 
failure is instantaneous for 4.20-rc1 with only 
ecb0a83e3198f2c1142901687afacbc73602a13b " ubd: remove use of 
blk_rq_map_sg" reverted.

Reverting both and restoring the driver to 4.19 state fixes things.

I am going to give it a go to debug exactly what breaks for writing in 
ecb0a83e3198f2c1142901687afacbc73602a13b " ubd: remove use of 
blk_rq_map_sg".

A.


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

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


  reply	other threads:[~2018-11-07 10:46 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-05 13:13 4.20-rc1 looks broken for UML Anton Ivanov
2018-11-05 15:22 ` Anton Ivanov
2018-11-05 22:07   ` Richard Weinberger
2018-11-06  7:03     ` Anton Ivanov
2018-11-06 15:00     ` Anton Ivanov
2018-11-06 15:07       ` Anton Ivanov
2018-11-06 18:00         ` Lance Roy
2018-11-06 18:12           ` Anton Ivanov
2018-11-06 17:04       ` Richard Weinberger
2018-11-06 17:25         ` Anton Ivanov
2018-11-06 19:09           ` Anton Ivanov
2018-11-06 19:56             ` Richard Weinberger
2018-11-06 20:49               ` Richard Weinberger
2018-11-07  7:53                 ` Christoph Hellwig
2018-11-07 10:46                   ` Anton Ivanov [this message]
2018-11-07 13:33                     ` Anton Ivanov
2018-11-06 17:42         ` Anton Ivanov

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=31d79c23-0fa0-956e-5477-0c326416fc45@kot-begemot.co.uk \
    --to=anton.ivanov@kot-begemot.co.uk \
    --cc=axboe@kernel.dk \
    --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.