This check effectively catches anon vma hierarchy inconsistence and some vma corruptions. It was effective for catching corner cases in anon vma reusing logic. For now this code seems stable so check could be hidden under CONFIG_DEBUG_VM and replaced with WARN because it's not so fatal.
Signed-off-by: Konstantin Khlebnikov <[email protected]> Suggested-by: Vasily Averin <[email protected]> --- mm/rmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/rmap.c b/mm/rmap.c index 395e314b7996..a8d52d3f40ed 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -409,7 +409,7 @@ void unlink_anon_vmas(struct vm_area_struct *vma) list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { struct anon_vma *anon_vma = avc->anon_vma; - BUG_ON(anon_vma->degree); + VM_WARN_ON(anon_vma->degree); put_anon_vma(anon_vma); list_del(&avc->same_vma);
