On 5/5/21 8:32 PM, Roman Gushchin wrote: > 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? Hmm I missed that Now I wonder why all kmalloc caches on my system have 0 aliases :) cat /sys/kernel/slab/kmalloc-*/aliases > It means they are not exempt actually. >
