Messages in this thread | | | Date | Wed, 8 May 2013 15:26:09 +0300 | Subject | Re: [GIT PULL] SLAB changes for v3.10 | From | Pekka Enberg <> |
| |
On Wed, May 8, 2013 at 2:58 PM, Glauber Costa <glommer@parallels.com> wrote: > My first guess is that it hit a NULL cache. Being a NULL pointer > dereference, the thing among all that has the biggest chances of being > NULL and accessed unconditionally is the cache pointer itself. > > Due to the size being too big. But if that were the case, he would have > hit the WARN_ON recently introduced: > > if (WARN_ON_ONCE(size > KMALLOC_MAX_SIZE)) > return NULL; > > > Is this WARN hit ?
I doubt it:
[ 0.000000] r7 : 00000000 r6 : 600001d3 r5 : 00000000 r4 : 00008000 [ 0.000000] r3 : 00000050 r2 : c06ec000 r1 : c06f77c8 r0 : c00eda9c
[ 0.000000] [<c00edab4>] (kmem_cache_alloc_trace+0x50/0x178) from [<c0086958>] (alloc_desc+0x24/0xb4)
It's the kzalloc_node() in kernel/irq/irqdesc.c::alloc_desc() and AFAICT based on r4 it's a 32 KB allocation. It's more likely that KMALLOC_SHIFT_HIGH is less than 25 and because kmalloc_index() doesn't respect it, we return a pointer to an uninitialized kmalloc cache.
Pekka
| |