[PATCH V2] arm64: hwpoison: add VM_FAULT_HWPOISON[_LARGE] handling
From: Punit Agrawal <hidden>
Date: 2017-03-07 20:50:15
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Punit Agrawal [off-list ref] 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.
quoted hunk
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 [off-list ref] 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 [off-list ref]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;