The patch below does not apply to the 4.19-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@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7b358c6f12dc82364f6d317f8c8f1d794adbc3f5 Mon Sep 17 00:00:00 2001

From: Ralph Campbell rcampbell@nvidia.com Date: Fri, 2 Aug 2019 21:49:08 -0700 Subject: [PATCH] mm/migrate.c: initialize pud_entry in migrate_vma() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

When CONFIG_MIGRATE_VMA_HELPER is enabled, migrate_vma() calls migrate_vma_collect() which initializes a struct mm_walk but didn't initialize mm_walk.pud_entry. (Found by code inspection) Use a C structure initialization to make sure it is set to NULL.

Link: http://lkml.kernel.org/r/20190719233225.12243-1-rcampbell@nvidia.com Fixes: 8763cb45ab967 ("mm/migrate: new memory migration helper for use with device memory") Signed-off-by: Ralph Campbell rcampbell@nvidia.com Reviewed-by: John Hubbard jhubbard@nvidia.com Reviewed-by: Andrew Morton akpm@linux-foundation.org Cc: "Jérôme Glisse" jglisse@redhat.com Cc: Mel Gorman mgorman@techsingularity.net Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org

diff --git a/mm/migrate.c b/mm/migrate.c index 515718392b24..a42858d8e00b 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -2340,16 +2340,13 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, static void migrate_vma_collect(struct migrate_vma *migrate) { struct mmu_notifier_range range; - struct mm_walk mm_walk; - - mm_walk.pmd_entry = migrate_vma_collect_pmd; - mm_walk.pte_entry = NULL; - mm_walk.pte_hole = migrate_vma_collect_hole; - mm_walk.hugetlb_entry = NULL; - mm_walk.test_walk = NULL; - mm_walk.vma = migrate->vma; - mm_walk.mm = migrate->vma->vm_mm; - mm_walk.private = migrate; + struct mm_walk mm_walk = { + .pmd_entry = migrate_vma_collect_pmd, + .pte_hole = migrate_vma_collect_hole, + .vma = migrate->vma, + .mm = migrate->vma->vm_mm, + .private = migrate, + };

mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm_walk.mm, migrate->start,