I wondered whether to post this munlocking rework in https://lore.kernel.org/linux-mm/35c340a6-96f-28a0-2b7b-2f9fbddc01f@xxxxxxxxxx/ There the discussion was OOM reaping, but the main reason for the rework has been catastrophic contention on i_mmap_rwsem when exiting from multiply mlocked files; and frustration with how contorted munlocking is. Here it is based on 5.17-rc2, applies also to -rc3, almost cleanly to mmotm 2022-02-03-21-58 (needs two easy fixups in mm/huge_memory.c); but likely to conflict (I hope not fundamentally) with several concurrent large patchsets. tl;dr mm/mlock.c | 634 +++++++++++++++----------------------- 23 files changed, 510 insertions(+), 779 deletions(-) In my own opinion, this is ready to go in: that whatever its defects, it's a big practical improvement over what's presently there. Others may differ; and it may be too much to arrive at a quick opinion on. My hope is that it will strike a chord with some who have laboured in this area in the past: I'll be short of time to do much more with it, so maybe someone else could take over if necessary. At present there's no update to Documentation/vm/unevictable-lru.rst: that always needs a different mindset, can follow later, please refer to commit messages for now. There are two half-related mm/thp patches at the end: enhancements we've had for a long time, but more suited after the mlock changes. 01/13 mm/munlock: delete page_mlock() and all its works 02/13 mm/munlock: delete FOLL_MLOCK and FOLL_POPULATE gupflags 03/13 mm/munlock: delete munlock_vma_pages_all(), allow oomreap 04/13 mm/munlock: rmap call mlock_vma_page() munlock_vma_page() 05/13 mm/munlock: replace clear_page_mlock() by final clearance 06/13 mm/munlock: maintain page->mlock_count while unevictable 07/13 mm/munlock: mlock_pte_range() when mlocking or munlocking 08/13 mm/migrate: __unmap_and_move() push good newpage to LRU 09/13 mm/munlock: delete smp_mb() from __pagevec_lru_add_fn() 10/13 mm/munlock: mlock_page() munlock_page() batch by pagevec 11/13 mm/munlock: page migration needs mlock pagevec drained 12/13 mm/thp: collapse_file() do try_to_unmap(TTU_BATCH_FLUSH) 13/13 mm/thp: shrink_page_list() avoid splitting VM_LOCKED THP include/linux/mm.h | 2 include/linux/mm_inline.h | 11 include/linux/mm_types.h | 19 + include/linux/rmap.h | 23 - kernel/events/uprobes.c | 7 mm/gup.c | 43 -- mm/huge_memory.c | 55 --- mm/hugetlb.c | 4 mm/internal.h | 64 ++- mm/khugepaged.c | 14 mm/ksm.c | 12 mm/madvise.c | 5 mm/memcontrol.c | 3 mm/memory.c | 45 -- mm/migrate.c | 42 +- mm/mlock.c | 634 +++++++++++++++----------------------- mm/mmap.c | 32 - mm/mmzone.c | 7 mm/oom_kill.c | 2 mm/rmap.c | 156 ++------- mm/swap.c | 89 ++--- mm/userfaultfd.c | 14 mm/vmscan.c | 6 23 files changed, 510 insertions(+), 779 deletions(-) Hugh
