Replace miss typing va->va_start > tmp_va->va_start and va->va_end < tmp_va->va_end with va->va_start > tmp_va->va_end and va->va_end < tmp_va->va_end. It ensures va and tmp never overlap.
> On Sep 4, 2016, at 9:29 PM, Peng Gao <[email protected]> wrote: > > I am browsing the code > > static void __insert_vmap_area(struct vmap_area *va) > { > struct rb_node **p = &vmap_area_root.rb_node; > struct rb_node *parent = NULL; > struct rb_node *tmp; > > while (*p) { > struct vmap_area *tmp_va; > > parent = *p; > tmp_va = rb_entry(parent, struct vmap_area, rb_node); > if (va->va_start < tmp_va->va_end) > p = &(*p)->rb_left; > else if (va->va_end > tmp_va->va_start) > p = &(*p)->rb_right; > else > BUG(); > } > > rb_link_node(&va->rb_node, parent, p); > rb_insert_color(&va->rb_node, &vmap_area_root); > > /* address-sort this list */ > tmp = rb_prev(&va->rb_node); > if (tmp) { > struct vmap_area *prev; > prev = rb_entry(tmp, struct vmap_area, rb_node); > list_add_rcu(&va->list, &prev->list); > } else > list_add_rcu(&va->list, &vmap_area_list); > } > > As far as I can know map_area is a range for the vmalloc to alloc > non-contigious memory, which confuses me is that why not use va->va_start > > tmp_va->va_start and va->va_end < tmp_va->va_end to insert a new vmap_area. > Can a virtual address mapping overlap? > > One more question > > In alloc_map_area, I found this part of code. > > /* from the starting point, walk areas until a suitable hole is found */ > while (addr + size > first->va_start && addr + size <= vend) { > if (addr + cached_hole_size < first->va_start) /* > cached_hole_size */ > cached_hole_size = first->va_start - addr; > addr = ALIGN(first->va_end, align); > if (addr + size < addr) > goto overflow; > > if (list_is_last(&first->list, &vmap_area_list)) > goto found; > > first = list_next_entry(first, list); > } > > It seems like just inert a map_area at the end of list, what dose suitable > hole means? > Why not add this? > > if(addr+size < first->va_start) > goto notound > _______________________________________________ Kernelnewbies mailing list [email protected] https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
