On 02/08/2024 16:55, David Hildenbrand wrote:
Let's remove yet another follow_page() user. Note that we have to do the
split without holding the PTL, after folio_walk_end(). We don't care
about losing the secretmem check in follow_page().
Hi David,
Our (arm64) CI is showing a regression in split_huge_page_test from mm selftests from next-20240805 onwards. Navigating around a couple of other lurking bugs, I was able to bisect to this change (which smells about right).
Newly failing test:
# # ------------------------------
# # running ./split_huge_page_test
# # ------------------------------
# # TAP version 13
# # 1..12
# # Bail out! Still AnonHugePages not split
# # # Planned tests != run tests (12 != 0)
# # # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
# # [FAIL]
# not ok 52 split_huge_page_test # exit=1
It's trying to split some pmd-mapped THPs then checking and finding that they are not split. The split is requested via /sys/kernel/debug/split_huge_pages, which I believe ends up in this function you are modifying here. Although I'll admit that looking at the change, there is nothing obviously wrong! Any ideas?