On Wed, May 05, 2021 at 08:02:06PM +0200, Vlastimil Babka wrote: > On 5/5/21 7:30 PM, Roman Gushchin wrote: > > On Wed, May 05, 2021 at 11:46:13AM -0400, Waiman Long wrote: > >> > >> With this change, all the objcg pointer array objects will come from > >> KMALLOC_NORMAL caches which won't have their objcg pointer arrays. So > >> both the recursive kfree() problem and non-freeable slab problem are > >> gone. Since both the KMALLOC_NORMAL and KMALLOC_CGROUP caches no longer > >> have mixed accounted and unaccounted objects, this will slightly reduce > >> the number of objcg pointer arrays that need to be allocated and save > >> a bit of memory. > > > > Unfortunately the positive effect of this change will be likely > > reversed by a lower utilization due to a larger number of caches. > > > > Btw, I wonder if we also need a change in the slab caches merging procedure? > > KMALLOC_NORMAL caches should not be merged with caches which can potentially > > include accounted objects. > > Good point. But looks like kmalloc* caches are extempt from all merging in > create_boot_cache() via > > s->refcount = -1; /* Exempt from merging for now */ Wait, s->refcount is adjusted to 1 in create_kmalloc_cache() after calling into create_boot_cache? It means they are not exempt actually.
