rem: struct qm_frag_end *end;
context: static inline void qm_detach_free(struct qm_block* qm, struct qm_frag* frag){	struct qm_frag *prev;	struct qm_frag *next;		struct qm_frag_end *end;	prev=FRAG_END(frag)->prev_free;	next=frag->u.nxt_free;	prev->u.nxt_free=next;	FRAG_END(next)->prev_free=prev;	}