tree 80e206d025be3823797924a8ea8b70c56a6deab9
parent a0acd820807680d2ccc4ef3448387fcdbf152c73
author Christoph Lameter <clameter@sgi.com> 1184670213 -0700
committer Linus Torvalds <torvalds@woody.linux-foundation.org> 1184692982 -0700

Add VM_BUG_ON in case someone uses page_mapping on a slab page

Detect slab objects being passed to the page oriented functions of the VM.

It is not sufficient to simply return NULL because the functions calling
page_mapping may depend on other items of the page_struct also to be setup
properly.  Moreover slab object may not be properly aligned.  The page
oriented functions of the VM expect to operate on page aligned, page sized
objects.  Operations on object straddling page boundaries may only affect the
objects partially which may lead to surprising results.

It is better to detect eventually remaining uses and eliminate them.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>