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Date:   Wed, 13 Sep 2023 11:10:10 +0200
From:   Cyril Hrubis <chrubis@suse.cz>
To:     kernel test robot <oliver.sang@intel.com>
Cc:     Edward AD <eadavis@sina.com>,
        syzbot+b591856e0f0139f83023@syzkaller.appspotmail.com,
        lkp@intel.com, syzkaller-bugs@googlegroups.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        oe-lkp@lists.linux.dev, akpm@linux-foundation.org,
        ltp@lists.linux.it
Subject: Re: [LTP] [PATCH] mm: as the same logic with queue_pages_range
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 <202309121302.8864096c-oliver.sang@intel.com>
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Hi!
> Running tests.......
> <<<test_start>>>
> tag=vma02 stime=1694438526
> cmdline="vma02"
> contacts=""
> analysis=exit
> <<<test_output>>>
> vma02       0  TINFO  :  pid = 3639 addr = 0x7f5202dd6000
> vma02       0  TINFO  :  start = 0x7f5202dd6000, end = 0x7f5202dd7000
> vma02       0  TINFO  :  start = 0x7f5202dd7000, end = 0x7f5202dd8000
> vma02       0  TINFO  :  start = 0x7f5202dd8000, end = 0x7f5202dd9000
> vma02       1  TFAIL  :  vma02.c:144: >1 unmerged VMAs.
> incrementing stop

So the test is reproducer for:

commit 9d8cebd4bcd7c3878462fdfda34bbcdeb4df7ef4
Author: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Date:   Fri Mar 5 13:41:57 2010 -0800

    mm: fix mbind vma merge problem

    Strangely, current mbind() doesn't merge vma with neighbor vma although it's possible.
    Unfortunately, many vma can reduce performance...


And what the test does is:

- map 3 continous pages
- popluate
- mbind() first page
- mbind() all three pages
- checks that there is only single VMA for the pages after second
  mbind()

-- 
Cyril Hrubis
chrubis@suse.cz