This series should apply to both mm-stable and mm-unstable, I am not sure whether it's even applicable to apply on mm-stable directly, but perhaps not urgently needed either. Anyway, it'll apply to either tree. It also means cc stable is not needed even if I had the Fixes attached. Patch 1 fixes that bug in mm-stable, patch 2 enhances the gup_longterm to be able to discover such issue. In general, the previous hugetlb rework [1] on gup-slow introduced an issue with R/O longterm pin. Nobody yet found it in either a real report or test case, probably because our test case doesn't yet cover it (not before patch 2), and it's also a pretty rare path: it only happens with Power longterm R/O pins on a page cache that is installed as a hugepd read-only. Please read each of the patch for details. I retested "./run_vmtests.sh -t gup_test -a" on a Power8 system with a Power8 VM, with 16MB hugepd hugepd entries installed. Note that I tested exactly the same matrix before, but patch 2 will change gup_longterm test, so it's actually slightly different test carried out, and the new test (gup_longterm.c, when apply patch 2 only) will hang mm-stable on Andrew's tree with that 16MB huge page. Thanks, [1] https://lore.kernel.org/r/20240327152332.950956-1-peterx@xxxxxxxxxx Peter Xu (2): mm/gup: Fix hugepd handling in hugetlb rework mm/selftests: Don't prefault in gup_longterm tests mm/gup.c | 64 ++++++++++++++--------- tools/testing/selftests/mm/gup_longterm.c | 12 +++-- 2 files changed, 48 insertions(+), 28 deletions(-) -- 2.44.0
