The quilt patch titled Subject: mempolicy: migration attempt to match interleave nodes: fix has been removed from the -mm tree. Its filename was mempolicy-migration-attempt-to-match-interleave-nodes-fix.patch This patch was dropped because it was folded into mempolicy-migration-attempt-to-match-interleave-nodes.patch ------------------------------------------------------ From: Hugh Dickins <hughd@xxxxxxxxxx> Subject: mempolicy: migration attempt to match interleave nodes: fix Date: Mon, 23 Oct 2023 23:50:42 -0700 (PDT) mm-unstable commit edd33b8807a1 ("mempolicy: migration attempt to match interleave nodes") added a second vma_iter search to do_mbind(), to determine the interleave index to be used in the MPOL_INTERLEAVE case. But sadly it added it just after the mmap_write_unlock(), leaving this new VMA search unprotected: and so syzbot reports suspicious RCU usage from lib/maple_tree.c:856. This could be fixed with an rcu_read_lock/unlock() pair (per Liam); but since we have been relying on the mmap_lock up to this point, it's slightly better to extend it over the new search too, for a well-defined result consistent with the policy this mbind() is establishing (rather than whatever might follow once the mmap_lock is dropped). Link: https://lkml.kernel.org/r/3311d544-fb05-a7f1-1b74-16aa0f6cd4fe@xxxxxxxxxx Fixes: edd33b8807a1 ("mempolicy: migration attempt to match interleave nodes") Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx> Reported-by: syzbot+79fcba037b6df73756d3@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://lore.kernel.org/linux-mm/000000000000c05f1b0608657fde@xxxxxxxxxx/ Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/mempolicy.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/mm/mempolicy.c~mempolicy-migration-attempt-to-match-interleave-nodes-fix +++ a/mm/mempolicy.c @@ -1291,8 +1291,6 @@ static long do_mbind(unsigned long start } } - mmap_write_unlock(mm); - if (!err && !list_empty(&pagelist)) { /* Convert MPOL_DEFAULT's NULL to task or default policy */ if (!new) { @@ -1334,7 +1332,11 @@ static long do_mbind(unsigned long start mmpol.ilx -= page->index >> order; } } + } + mmap_write_unlock(mm); + + if (!err && !list_empty(&pagelist)) { nr_failed |= migrate_pages(&pagelist, alloc_migration_target_by_mpol, NULL, (unsigned long)&mmpol, MIGRATE_SYNC, _ Patches currently in -mm which might be from hughd@xxxxxxxxxx are ext4-add-__gfp_nowarn-to-gfp_nowait-in-readahead.patch mm-mlock-avoid-folio_within_range-on-ksm-pages.patch hugetlbfs-drop-shared-numa-mempolicy-pretence.patch kernfs-drop-shared-numa-mempolicy-hooks.patch mempolicy-fix-migrate_pages2-syscall-return-nr_failed.patch mempolicy-trivia-delete-those-ancient-pr_debugs.patch mempolicy-trivia-slightly-more-consistent-naming.patch mempolicy-trivia-use-pgoff_t-in-shared-mempolicy-tree.patch mempolicy-mpol_shared_policy_init-without-pseudo-vma.patch mempolicy-remove-confusing-mpol_mf_lazy-dead-code.patch mm-add-page_rmappable_folio-wrapper.patch mempolicy-alloc_pages_mpol-for-numa-policy-without-vma.patch mempolicy-mmap_lock-is-not-needed-while-migrating-folios.patch mempolicy-migration-attempt-to-match-interleave-nodes.patch