Ceph » Linux kernel client

Sorry I didn't see this earlier.

The panic is not in ceph_kvmalloc() but in the guts of slab memory allocator. It's hard to make conclusions from the backtrace alone, the best I can tell is it died from a page fault in mm/slub.c

244 static inline void *get_freepointer(struct kmem_cache *s, void *object)
245 {
246         return *(void **)(object + s->offset); <<--
247 }

on a invalid *object - 0x6232ae8. This value came from

2416         preempt_enable();
2417 
2418         object = c->freelist; <<--
2419         page = c->page;
2420         if (unlikely(!object || !node_match(page, node))) {

which suggests a busted struct kmem_cache_cpu. How exactly it got busted is an open question and it probably has to do with the sudden memory usage spike shown on your graph. More questions then answers for sure, if you can reproduce this on a latest kernel we can take a deeper look - a lot of changes went into cephfs caps-related bits since 3.19.5.