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mm: validate the mm before dropping the mmap lock 

Commit 408579cd62 ("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 <oliver.sang@intel.com>
Link: https://lore.kernel.org/lkml/ZKIsoMOT71uwCIZX@xsang-OptiPlex-9020/
Fixes: 408579cd62 ("mm: Update do_vmi_align_munmap() return semantics")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2023-07-03 10:08:50 -07:00
parent f66066bc51
commit ae80b40419
1 changed files with 1 additions and 2 deletions
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3
mm/mmap.c
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@ -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;
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