On 9/27/18 7:15 PM, Dmitry Vyukov wrote: > From: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > > Slub does not call kmalloc_slab() for sizes > KMALLOC_MAX_CACHE_SIZE, > instead it falls back to kmalloc_large(). > For slab KMALLOC_MAX_CACHE_SIZE == KMALLOC_MAX_SIZE and it calls > kmalloc_slab() for all allocations relying on NULL return value > for over-sized allocations. > This inconsistency leads to unwanted warnings from kmalloc_slab() > for over-sized allocations for slab. Returning NULL for failed > allocations is the expected behavior. > > Make slub and slab code consistent by checking size > > KMALLOC_MAX_CACHE_SIZE in slab before calling kmalloc_slab(). > > While we are here also fix the check in kmalloc_slab(). > We should check against KMALLOC_MAX_CACHE_SIZE rather than > KMALLOC_MAX_SIZE. It all kinda worked because for slab the > constants are the same, and slub always checks the size against > KMALLOC_MAX_CACHE_SIZE before kmalloc_slab(). > But if we get there with size > KMALLOC_MAX_CACHE_SIZE anyhow > bad things will happen. For example, in case of a newly introduced > bug in slub code. > > Also move the check in kmalloc_slab() from function entry > to the size > 192 case. This partially compensates for the additional > check in slab code and makes slub code a bit faster > (at least theoretically). > > Also drop __GFP_NOWARN in the warning check. > This warning means a bug in slab code itself, > user-passed flags have nothing to do with it. > > Nothing of this affects slob. > > Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Cc: Christoph Lameter <cl@xxxxxxxxx> > Cc: Pekka Enberg <penberg@xxxxxxxxxx> > Cc: David Rientjes <rientjes@xxxxxxxxxx> > Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: linux-mm@xxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > Reported-by: syzbot+87829a10073277282ad1@xxxxxxxxxxxxxxxxxxxxxxxxx > Reported-by: syzbot+ef4e8fc3a06e9019bb40@xxxxxxxxxxxxxxxxxxxxxxxxx > Reported-by: syzbot+6e438f4036df52cbb863@xxxxxxxxxxxxxxxxxxxxxxxxx > Reported-by: syzbot+8574471d8734457d98aa@xxxxxxxxxxxxxxxxxxxxxxxxx > Reported-by: syzbot+af1504df0807a083dbd9@xxxxxxxxxxxxxxxxxxxxxxxxx Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
