Re: [Bug 202149] New: NULL Pointer Dereference in __split_huge_pmd on PPC64LE

It's normal daily usage on a workstation (TALOS 2). I've seen it at least twice, both times in rustc, though I've run rustc more times than I can count. Note that the program that triggered it was running in lxc and it only happened after upgrading to 4.19.

On Jan 9, 2019, at 06:50, Aneesh Kumar K.V [off-list ref] wrote:

Matt Corallo [off-list ref] writes:

quoted

.config follows. I have not tested with 64K pages as, sadly, I have a 
large BTRFS volume that was formatted on x86, and am thus stuck with 4K 
pages. Note that this is roughly the Debian kernel, so it has whatever 
patches Debian defaults to applying, a list of which follows.

What is the test you are running? I tried a 4K page size config on P9. I
am running ltp test suite there. Also tried few thp memremap tests.
Nothing hit that.

root@:~/tests/ltp/testcases/kernel/mem/thp# getconf  PAGESIZE
4096
root@ltc-boston123:~/tests/ltp/testcases/kernel/mem/thp# grep thp /proc/vmstat 
thp_fault_alloc 641141
thp_fault_fallback 0
thp_collapse_alloc 90
thp_collapse_alloc_failed 0
thp_file_alloc 0
thp_file_mapped 0
thp_split_page 1
thp_split_page_failed 0
thp_deferred_split_page 641150
thp_split_pmd 24
thp_zero_page_alloc 1
thp_zero_page_alloc_failed 0
thp_swpout 0
thp_swpout_fallback 0
root@:~/tests/ltp/testcases/kernel/mem/thp# 

-aneesh