Messages in this thread | | | From | Punit Agrawal <> | Subject | Re: [PATCH V2] arm64: hwpoison: add VM_FAULT_HWPOISON[_LARGE] handling | Date | Tue, 07 Mar 2017 19:56:15 +0000 |
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Punit Agrawal <punit.agrawal@arm.com> writes:
[...]
> > The code looks good but I ran into some failures while running the > hugepages hwpoison tests from mce-tests suite[0]. I get a bad pmd error > in dmesg - > > [ 344.165544] mm/pgtable-generic.c:33: bad pmd 000000083af00074. > > I suspect that this is due to the huge pte accessors not correctly > dealing with poisoned entries (which are represented as swap entries).
I think I've got to the bottom of the issue - the problem is due to huge_pte_at() returning NULL for poisoned pmd entries (which in turn is due to pmd_present() not handling poisoned pmd entries correctly)
The following is the call chain for the failure case.
do_munmap unmap_region unmap_vmas unmap_single_vma __unmap_hugepage_range_final # The test case uses hugepages __unmap_hugepage_range huge_pte_offset # Returns NULL for a poisoned pmd
Reverting 5bb1cc0ff9a6 ("arm64: Ensure pmd_present() returns false after pmd_mknotpresent()") fixes the problem for me but I don't think that is the right fix.
While I work on a proper fix, it would be great if you can confirm that reverting 5bb1cc0ff9a6 makes the problem go away at your end.
> > I am investigating the failure but could you try running the tests at > your end as well. > > To run the tests, I cloned the repository[0]. It test needs a simple fix > at the end of this mail to run correctly. With that applied and running > as root - > > # cd mce-test/cases/function/hwpoison > # ./run_hugepage.sh > > > [0] https://git.kernel.org/cgit/utils/cpu/mce/mce-test.git/ > > --------->8-------------- > commit cb5c61f18dd86baf01b90404d4ecf51dd3d176c7 > Author: Punit Agrawal <punit.agrawal@arm.com> > Date: Thu Mar 2 18:24:40 2017 +0000 > > Use correct return type for getopt_long > > getopt_long returns an int. Fix the return type to avoid issues when > checking for negative error codes on architectures with unsigned char, > e.g., arm. > > Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> > > diff --git a/cases/function/hwpoison/thugetlb.c b/cases/function/hwpoison/thugetlb.c > index 92dc7d2..fbcf426 100644 > --- a/cases/function/hwpoison/thugetlb.c > +++ b/cases/function/hwpoison/thugetlb.c > @@ -125,7 +125,7 @@ int main(int argc, char *argv[]) > int forkflag = 0; > int privateflag = 0; > int cowflag = 0; > - char c; > + int c; > pid_t pid = 0; > void *expected_addr = NULL; > struct sembuf sembuffer;
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