Re: dax pmd fault handler never returns to userspace
From: Dan Williams <hidden>
Date: 2015-11-18 21:57:25
Also in:
linux-fsdevel
Possibly related (same subject, not in this thread)
- 2015-11-19 · Re: dax pmd fault handler never returns to userspace · Dave Chinner <david@fromorbit.com>
- 2015-11-18 · Re: dax pmd fault handler never returns to userspace · Dan Williams <hidden>
- 2015-11-18 · Re: dax pmd fault handler never returns to userspace · Ross Zwisler <hidden>
- 2015-11-18 · Re: dax pmd fault handler never returns to userspace · Jeff Moyer <hidden>
- 2015-11-18 · Re: dax pmd fault handler never returns to userspace · Jeff Moyer <hidden>
On Wed, Nov 18, 2015 at 1:33 PM, Toshi Kani [off-list ref] wrote:
I am seeing a similar/same problem in my test. I think the problem is that in case of a WP fault, wp_huge_pmd() -> __dax_pmd_fault() -> vmf_insert_pfn_pmd(), which is a no-op since the PMD is mapped already. We need WP handling for this PMD map. If it helps, I have attached change for follow_trans_huge_pmd(). I have not tested much, though.
Interesting, I didn't get this far because my tests were crashing the kernel. I'll add this case the pmd fault test in ndctl.