Re: x86: bad pte in pageattr_test

[Andrey Ryabinin]

On 04/11/2016 11:28 AM, Dmitry Vyukov wrote:
> Hello,
> 
> I've got the following WARNING while running syzkaller fuzzer:
> 
> CPA ffff880054118000: bad pte after revert 8000000054118363
> ------------[ cut here ]------------
> WARNING: CPU: 2 PID: 1503 at arch/x86/mm/pageattr-test.c:226
> pageattr_test+0xa6c/0xd10
> NOT PASSED. Please report.
> Modules linked in:
> CPU: 2 PID: 1503 Comm: pageattr-test Not tainted 4.6.0-rc2+ #346
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>  ffffffff87eb25c0 ffff88003b627a70 ffffffff82c8b17f ffffffff81490b58
>  fffffbfff0fd64b8 ffff88003b627ae8 0000000000000000 ffffffff86a77e00
>  ffffffff8129487c 0000000000000009 ffff88003b627ab8 ffffffff8136639f
> Call Trace:
>  [<     inline     >] __dump_stack lib/dump_stack.c:15
>  [<ffffffff82c8b17f>] dump_stack+0x12e/0x18f lib/dump_stack.c:51
>  [<ffffffff8136639f>] __warn+0x19f/0x1e0 kernel/panic.c:512
>  [<ffffffff8136648c>] warn_slowpath_fmt+0xac/0xd0 kernel/panic.c:527
>  [<ffffffff8129487c>] pageattr_test+0xa6c/0xd10 arch/x86/mm/pageattr-test.c:226
>  [<ffffffff81294b3b>] do_pageattr_test+0x1b/0x60 arch/x86/mm/pageattr-test.c:240
>  [<ffffffff813cde7f>] kthread+0x23f/0x2d0 drivers/block/aoe/aoecmd.c:1303

It seems, that your script is buggy. It should be kthread() from kernel/kthread.c here.


>  [<ffffffff867b6252>] ret_from_fork+0x22/0x50 arch/x86/entry/entry_64.S:392
> ---[ end trace e669a8d69b836be8 ]---
> 
> Unfortunately it is not reproducible, tried bumping checking frequency to 1.
> 
> On commit 541d8f4d59d79f5d37c8c726f723d42ff307db57 (Apr 5).
> 
> For the repcord, full syzkaller log:
> https://gist.githubusercontent.com/dvyukov/323ff7275c5ac38156cb40caeacac057/raw/0836f8dd81024e441f81caebdcb73ca1221aef97/gistfile1.txt
>