[Bug 203107] Bad page map in process during boot

[bugzilla-daemon@bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=203107

--- Comment #4 from Vlastimil Babka (vbabka@suse.cz) ---
On 4/4/19 3:08 PM, Kirill A. Shutemov wrote:
> On Tue, Apr 02, 2019 at 12:16:13PM +0200, Jan Kara wrote:
>> Switching to email...
>>
>> On Fri 29-03-19 20:46:22, bugzilla-daemon@bugzilla.kernel.org wrote:
>>> https://bugzilla.kernel.org/show_bug.cgi?id=203107
>>>
>>>             Bug ID: 203107
>>>            Summary: Bad page map in process during boot
>>>            Product: File System
>>>            Version: 2.5
>>>     Kernel Version: 5.0.5
>>>           Hardware: All
>>>                 OS: Linux
>>>               Tree: Mainline
>>>             Status: NEW
>>>           Severity: normal
>>>           Priority: P1
>>>          Component: ext4
>>>           Assignee: fs_ext4@kernel-bugs.osdl.org
>>>           Reporter: echto1@gmail.com
>>>         Regression: No
>>>
>>> Error occurs randomly at boot after upgrading kernel from 5.0.0 to 5.0.4.
>>>
>>> https://justpaste.it/387uf
>>
>> I don't think this is an ext4 error. Sure this is an error in file mapping
>> of libblkid.so.1.1.0 (which is handled by ext4) but the filesystem has very
>> little to say wrt how or which PTEs are installed. And the problem is that
>> invalid PTE (dead000000000100) is present in page tables. So this looks
>> more like a problem in MM itself. Adding MM guys to CC.
> 
> 0xdead000000000100 and 0xdead000000000200 are LIST_POISON1 and
> LIST_POISON2 repectively. Have no idea how would they end up in page table.

It's possible that CONFIG_DEBUG_LIST could catch the issue. Between
5.0.0 to 5.0.4 it should be also relatively easy to bisect with the
stable git tree [1], although if it happens randomly, you need to
perform enough attempts to accurately determine which commit is "good".

[1] git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git

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