Re: Frequent ext4 oopses with 4.4.0 on Intel NUC6i3SYB

On 04.10.2016 10:41, Jan Kara wrote:

The problem looks like memory corruption:

[...]

Huh, very interesting -- thanks for the walkthrough!

Anyway, adding linux-mm to CC since this does not look ext4 related but
rather mm related issue.

Bugs like these are always hard to catch, usually it's some flaky device
driver, sometimes also flaky HW. You can try running kernel with various
debug options enabled in a hope to catch the code corrupting memory
earlier - e.g. CONFIG_DEBUG_PAGE_ALLOC sometimes catches something,
CONFIG_SLAB_DEBUG can be useful as well. Another option is to get a
crashdump when the oops happens (although that's going to be a pain to
setup on such a small machine) and then look at which places point to
the corrupted memory - sometimes you can find old structures pointing to
the place and find the use-after-free issue or stuff like that...

Uhh, that sounds painful. So I'm following Ted's advice and building
myself a 4.8 as we speak.

If the problem is fixed, would it be of any help to trace the source by
going back to the 4.4.0 and reproduce with the debug symbols you
mentioned? I don't think a memdump would be difficult on the machine
(while it certainly has a small form factor, it's got a 1 TB hdd and 16
GB of RAM, so it's not really that small).

Cheers,
Johannes

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