The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 24bf08c4376be417f16ceb609188b16f461b0443 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2023042216-retainer-immersion-5428@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: 24bf08c4376b ("mm/userfaultfd: fix uffd-wp handling for THP migration entries") 6c287605fd56 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive") 6c54dc6c7437 ("mm/rmap: use page_move_anon_rmap() when reusing a mapped PageAnon() page exclusively") 28c5209dfd5f ("mm/rmap: pass rmap flags to hugepage_add_anon_rmap()") f1e2db12e45b ("mm/rmap: remove do_page_add_anon_rmap()") 14f9135d5470 ("mm/rmap: convert RMAP flags to a proper distinct rmap_t type") fb3d824d1a46 ("mm/rmap: split page_dup_rmap() into page_dup_file_rmap() and page_try_dup_anon_rmap()") b51ad4f8679e ("mm/memory: slightly simplify copy_present_pte()") 623a1ddfeb23 ("mm/hugetlb: take src_mm->write_protect_seq in copy_hugetlb_page_range()") 3bff7e3f1f16 ("mm/huge_memory: streamline COW logic in do_huge_pmd_wp_page()") c145e0b47c77 ("mm: streamline COW logic in do_swap_page()") 84d60fdd3733 ("mm: slightly clarify KSM logic in do_swap_page()") 53a05ad9f21d ("mm: optimize do_wp_page() for exclusive pages in the swapcache") 9030fb0bb9d6 ("Merge tag 'folio-5.18c' of git://git.infradead.org/users/willy/pagecache") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 24bf08c4376be417f16ceb609188b16f461b0443 Mon Sep 17 00:00:00 2001 From: David Hildenbrand <david@xxxxxxxxxx> Date: Wed, 5 Apr 2023 18:02:35 +0200 Subject: [PATCH] mm/userfaultfd: fix uffd-wp handling for THP migration entries Looks like what we fixed for hugetlb in commit 44f86392bdd1 ("mm/hugetlb: fix uffd-wp handling for migration entries in hugetlb_change_protection()") similarly applies to THP. Setting/clearing uffd-wp on THP migration entries is not implemented properly. Further, while removing migration PMDs considers the uffd-wp bit, inserting migration PMDs does not consider the uffd-wp bit. We have to set/clear independently of the migration entry type in change_huge_pmd() and properly copy the uffd-wp bit in set_pmd_migration_entry(). Verified using a simple reproducer that triggers migration of a THP, that the set_pmd_migration_entry() no longer loses the uffd-wp bit. Link: https://lkml.kernel.org/r/20230405160236.587705-2-david@xxxxxxxxxx Fixes: f45ec5ff16a7 ("userfaultfd: wp: support swap and page migration") Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> Reviewed-by: Peter Xu <peterx@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Cc: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 032fb0ef9cd1..e3706a2b34b2 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1838,10 +1838,10 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, if (is_swap_pmd(*pmd)) { swp_entry_t entry = pmd_to_swp_entry(*pmd); struct page *page = pfn_swap_entry_to_page(entry); + pmd_t newpmd; VM_BUG_ON(!is_pmd_migration_entry(*pmd)); if (is_writable_migration_entry(entry)) { - pmd_t newpmd; /* * A protection check is difficult so * just be safe and disable write @@ -1855,8 +1855,16 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, newpmd = pmd_swp_mksoft_dirty(newpmd); if (pmd_swp_uffd_wp(*pmd)) newpmd = pmd_swp_mkuffd_wp(newpmd); - set_pmd_at(mm, addr, pmd, newpmd); + } else { + newpmd = *pmd; } + + if (uffd_wp) + newpmd = pmd_swp_mkuffd_wp(newpmd); + else if (uffd_wp_resolve) + newpmd = pmd_swp_clear_uffd_wp(newpmd); + if (!pmd_same(*pmd, newpmd)) + set_pmd_at(mm, addr, pmd, newpmd); goto unlock; } #endif @@ -3251,6 +3259,8 @@ int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, pmdswp = swp_entry_to_pmd(entry); if (pmd_soft_dirty(pmdval)) pmdswp = pmd_swp_mksoft_dirty(pmdswp); + if (pmd_uffd_wp(pmdval)) + pmdswp = pmd_swp_mkuffd_wp(pmdswp); set_pmd_at(mm, address, pvmw->pmd, pmdswp); page_remove_rmap(page, vma, true); put_page(page);
