[Based on tag v5.14, but it should still apply to -mm too. If not, I can repost anytime] Hugh, So I found one thing that I feel like a bug of commit 22061a1ffabdb9c3, but I'm not sure. If that's the case, patch 5 of this series may be the fix for it. The problem is unmap_mapping_page() in current tree is calling unmap_mapping_range_tree() with a details pointer, while by default when detail pointer is specified, it means "we want to skip zapping swap entries". I didn't mention this in v1 simply because I thought it was fine, e.g., swap entry won't be kept in shmem ptes so skipped is okay (it is never okay with shmem uffd-wp but uffd-wp code is not landed yet). However I just remembered there could also be e.g. shmem migration entries if I'm not wrong. From that pov, skipping swap entries for unmap_mapping_page() seems wrong. Would you please help check? It'll be great if you can comment on patch 1 too, to see whether that's okay and what I could have been missing there (e.g., if you have other concern on breaking stuff, I'll be happy to test). v2: - Patch "mm: Clear vmf->pte after pte_unmap_same() returns" - Remove one comment [David] - Collect r-b for patch 2/3 - Rewrite the last two patches to drop ZAP_FLAG_CHECK_MAPPING, dropping Alistair's r-b on patch 5 because it changed [David, Matthew] ===== v1 cover letter ===== I picked up these patches from uffd-wp v5 series here: https://lore.kernel.org/lkml/20210715201422.211004-1-peterx@xxxxxxxxxx/ IMHO all of them are very nice cleanups to existing code already, they're all small and self-contained. They'll be needed by uffd-wp coming series. I would appreciate if they can be accepted earlier, so as to not carry them over always with the uffd-wp series. I removed some CC from the uffd-wp v5 series to reduce the noise, and added a few more into it. Reviews are greatly welcomed, thanks. Peter Xu (5): mm/shmem: Unconditionally set pte dirty in mfill_atomic_install_pte mm: Clear vmf->pte after pte_unmap_same() returns mm: Drop first_index/last_index in zap_details mm: Add zap_skip_check_mapping() helper mm: Add ZAP_FLAG_SKIP_SWAP and zap_flags include/linux/mm.h | 33 ++++++++++++++++++-- mm/memory.c | 76 +++++++++++++++++++--------------------------- mm/shmem.c | 1 - mm/userfaultfd.c | 3 +- 4 files changed, 62 insertions(+), 51 deletions(-) -- 2.31.1
