From ae80b404198434e49e903dc3b1ba83e2c7bb3ee2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Mon, 3 Jul 2023 10:08:50 -0700 Subject: [PATCH] mm: validate the mm before dropping the mmap lock Commit 408579cd627a ("mm: Update do_vmi_align_munmap() return semantics") made the return value and locking semantics of do_vmi_align_munmap() more straightforward, but in the process it ended up unlocking the mmap lock just a tad too early: the debug code doing the mmap layout validation still needs to run with the lock held, or things might change under it while it's trying to validate things. So just move the unlocking to after the validate_mm() call. Reported-by: kernel test robot Link: https://lore.kernel.org/lkml/ZKIsoMOT71uwCIZX@xsang-OptiPlex-9020/ Fixes: 408579cd627a ("mm: Update do_vmi_align_munmap() return semantics") Signed-off-by: Linus Torvalds --- mm/mmap.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 51e70fa..547b405 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2554,11 +2554,10 @@ do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma, mas_set(&mas_detach, start); remove_mt(mm, &mas_detach); __mt_destroy(&mt_detach); + validate_mm(mm); if (unlock) mmap_read_unlock(mm); - - validate_mm(mm); return 0; clear_tree_failed: -- 2.7.4