On 02/22/2013 07:00 PM, Christoph Lameter wrote: > On Fri, 22 Feb 2013, Glauber Costa wrote: > >> Although not verified in practice, I also point out that it is not safe to scan >> the full list only when debugging is on in this case. As unlikely as it is, it >> is theoretically possible for the pages to be full. If they are, they will >> become unreachable. Aside from scanning the full list, we also need to make >> sure that the pages indeed sit in there: the easiest way to do it is to make >> sure the boot caches have the SLAB_STORE_USER debug flag set. > > SLAB_STORE_USER typically increases the size of the managed object. It is > not available when slab debugging is not compiled in. There is no list of > full slab objects that is maintained in the non debug case and if the > allocator is compiled without debug support also the code to manage full > lists will not be present. > > Only one or two kmem_cache item is allocated in the bootstrap code and so > far the size of the objects was signficantly smaller than page size. So > the slab pages will be on the partial lists. Why are your slab management > structures so large that a page can no longer contain multiple objects? > They are not. As I've mentioned in the description, the real bug is from partial slabs being temporarily in the cpu_slab during a recent allocation and therefore unreachable through the partial list. I've just read the code, and it seemed to me that theoretically that could happen. I agree with you that this is an unlikely scenario and if you prefer I can resend the patch without that part. Would that be preferable ? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>