Re: [PULL 00/31] testing/next and other misc fixes

[Alex Bennée]

Peter Maydell <peter.maydell@linaro.org> writes:

(adding the s390x people to the CC if they have any clues)

> On Wed, 12 Jan 2022 at 11:27, Alex Bennée <alex.bennee@linaro.org> wrote:
>>
>> The following changes since commit bf99e0ec9a51976868d7a8334620716df15fe7fe:
>>
>>   Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging 
>> (2022-01-11 10:12:29 +0000)
>>
>> are available in the Git repository at:
>>
>>   https://github.com/stsquad/qemu.git tags/pull-for-7.0-110122-1
>>
>> for you to fetch changes up to dbd30b7abee963f4fb08892a7d7f920bb76ece58:
>>
>>   linux-user: Remove the deprecated ppc64abi32 target (2022-01-11 13:00:53 
>> +0000)
>>
<snip>
> This seems to fail the ubuntu-18.04-s390x-all-linux-static job
> with segfaults running linux-user binaries (not always the same
> binary), eg:
> https://gitlab.com/qemu-project/qemu/-/jobs/1968789446
> https://gitlab.com/qemu-project/qemu/-/jobs/1968080419

*sigh*

So the regression is caused by:

  linux-user: don't adjust base of found hole

However it only occurs when pgb_static starts base at a low address. For
example:

  pgb_find_hole: base @ 13dd000 for 17432080 bytes
  pgb_static: base @ 13dd000 for 17432080 bytes
  Locating guest address space @ 0x13dd000

fails whereas:

  pgb_find_hole: base @ 41f97000 for 17432080 bytes      
  pgb_static: base @ 41f97000 for 17432080 bytes        
  Locating guest address space @ 0x41f97000      

works.

What I find confusing is why we end up with different addresses when
both QEMU and the test binary are static allocations. However the
varying allocation occurs before the change but without triggering the
crash:

  pgb_static: base @ 3dd000 for 17432080 bytes
  pgb_static: base @ 3dd000 for 17432080 bytes
  pgb_static: base @ 41246000 for 17432080 bytes
  pgb_static: base @ 3dd000 for 17432080 bytes
  pgb_static: base @ 40a2a000 for 17432080 bytes
  pgb_static: base @ 3dd000 for 17432080 bytes
  pgb_static: base @ 3dd000 for 17432080 bytes
  pgb_static: base @ 4060c000 for 17432080 bytes
  pgb_static: base @ 3dd000 for 17432080 bytes
  pgb_static: base @ 3dd000 for 17432080 bytes
  pgb_static: base @ 3dd000 for 17432080 bytes

>
>
> thanks
> -- PMM


-- 
Alex Bennée