lkml.org 
[lkml]   [2012]   [Mar]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 06/11] huge-memory: Use lockdep_assert_held
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


\
 
 \ /
  Last update: 2012-03-16 22:21    [W:0.096 / U:0.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site