Re: [PATCH] mm: BUG when __kmap_atomic_idx crosses boundary

[Davidlohr Bueso]

On Wed, 2014-07-30 at 03:37 -0700, Davidlohr Bueso wrote:
> On Wed, 2014-07-30 at 02:06 -0700, Andrew Morton wrote:
> > On Wed, 30 Jul 2014 14:22:35 +0530 Chintan Pandya <cpandya@xxxxxxxxxxxxxx> wrote:
> > 
> > > __kmap_atomic_idx >= KM_TYPE_NR or < ZERO is a bug.
> > > Report it even if CONFIG_DEBUG_HIGHMEM is not enabled.
> > > That saves much debugging efforts.
> > 
> > Please take considerably more care when preparing patch changelogs.
> > 
> > kmap_atomic() is a very commonly called function so we'll need much
> > more detail than this to justify adding overhead to it.
> > 
> > I don't think CONFIG_DEBUG_HIGHMEM really needs to exist.  We could do
> > s/CONFIG_DEBUG_HIGHMEM/CONFIG_DEBUG_VM/g and perhaps your secret bug
> > whatever it was would have been found more easily.
> 
> Agreed, it would be nice to fold DEBUG_HIGHMEM into DEBUG_VM. However
> you'd still need some kind of intermediate option as DEBUG_VM must still
> exist if !HIGHMEM.

Actually no, it's a lot more straightforward than I thought.

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