Messages in this thread | | | Date | Fri, 16 Mar 2012 14:18:57 -0700 (PDT) | From | Hugh Dickins <> | Subject | Re: [PATCH 06/11] huge-memory: Use lockdep_assert_held |
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On Fri, 16 Mar 2012, Andrea Arcangeli wrote: > On Fri, Mar 16, 2012 at 12:00:59PM -0700, Andi Kleen wrote: > > From: Andi Kleen <ak@linux.intel.com> > > > > Use lockdep_assert_held to check for locks instead of an opencoded > > variant. > > > > Cc: aarcange@redhat.com > > Signed-off-by: Andi Kleen <ak@linux.intel.com> > > --- > > mm/huge_memory.c | 4 ++-- > > mm/swap.c | 2 +- > > 2 files changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > > index 91d3efb..28669c6 100644 > > --- a/mm/huge_memory.c > > +++ b/mm/huge_memory.c > > @@ -2083,7 +2083,7 @@ static void collect_mm_slot(struct mm_slot *mm_slot) > > { > > struct mm_struct *mm = mm_slot->mm; > > > > - VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); > > + lockdep_assert_held(&khugepaged_mm_lock); > > This check was intended to be a VM debug check, so getting enabled by > DEBUG_VM, not through lockdep. I mean I always have DEBUG_VM enabled > in all my kernels, but lockdep only enabled on my test system. So it's > not an opencoded variant strictly speaking. > > My estimate is that what gets more tested is BUG_ON, second VM_BUG_ON, > third LOCKDEP.
My estimate too.
> But hey, this code has been tested for a while so I'm > neutral and if you prefer the lockdep version it's up to you.
Yes, it's not as if these are public interfaces used by drivers and filesystems: they have very few callsites, and by now those lines are mostly useful as documentation.
Andrew did mention assert_spin_locked() when I added those NR_CPUS conditions, but we preferred VM_BUG_ON to BUG_ON, and I'm content with Andi's further restriction to lockdep.
Acked-by: Hugh Dickins <hughd@google.com>
Hugh
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