Re: [BUG] madvise05 leads kernel panic on 4.9.122

From: Yang Shi
Date: Tue Aug 21 2018 - 17:32:25 EST




On 8/21/18 1:36 PM, Andi Kleen wrote:
On Tue, Aug 21, 2018 at 01:30:20PM -0700, yang.shi@xxxxxxxxxxxxxxxxx wrote:

On 8/21/18 11:43 AM, David Woodhouse wrote:
On Tue, 2018-08-21 at 11:37 -0700, Yang Shi wrote:
I just ran some regression test on stable 4.9.122 with LTP. madvise05
triggers the below kernel panic:
Thanks, David. It works. A silly question, I don't get why this commit could
solve this issue, it looks just like a code refactor. Just because it
changed how to get pfn from page table entries? And, this may cause some
mismatch on 4.9 stable without it?
With the L1TF patches open coded pte_val() to get the PFN can cause problems
because it doesn't do the invert for PROT_NONE mappings

The cleanup changes the open coded versions to use p*_pfn(), which always
works correctly.

Thanks. Got it.


-Andi