From: Joonsoo Kim <js1...@gmail.com> This patch is preparing step for removing vmlist entirely. For above purpose, we change iterating a vmap_list codes to iterating a vmap_area_list. It is somewhat trivial change, but just one thing should be noticed.
Using vmap_area_list in vmallocinfo() introduce ordering problem in SMP system. In s_show(), we retrieve some values from vm_struct. vm_struct's values is not fully setup when va->vm is assigned. Full setup is notified by removing VM_UNLIST flag without holding a lock. When we see that VM_UNLIST is removed, it is not ensured that vm_struct has proper values in view of other CPUs. So we need smp_[rw]mb for ensuring that proper values is assigned when we see that VM_UNLIST is removed. Therefore, this patch not only change a iteration list, but also add a appropriate smp_[rw]mb to right places. Signed-off-by: Joonsoo Kim <js1...@gmail.com> Signed-off-by: Joonsoo Kim <iamjoonsoo....@lge.com> diff --git a/mm/vmalloc.c b/mm/vmalloc.c index aee1f61..bda6cef 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1304,7 +1304,14 @@ static void insert_vmalloc_vmlist(struct vm_struct *vm) { struct vm_struct *tmp, **p; + /* + * Before removing VM_UNLIST, + * we should make sure that vm has proper values. + * Pair with smp_rmb() in show_numa_info(). + */ + smp_wmb(); vm->flags &= ~VM_UNLIST; + write_lock(&vmlist_lock); for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) { if (tmp->addr >= vm->addr) @@ -2542,19 +2549,19 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms) #ifdef CONFIG_PROC_FS static void *s_start(struct seq_file *m, loff_t *pos) - __acquires(&vmlist_lock) + __acquires(&vmap_area_lock) { loff_t n = *pos; - struct vm_struct *v; + struct vmap_area *va; - read_lock(&vmlist_lock); - v = vmlist; - while (n > 0 && v) { + spin_lock(&vmap_area_lock); + va = list_entry((&vmap_area_list)->next, typeof(*va), list); + while (n > 0 && &va->list != &vmap_area_list) { n--; - v = v->next; + va = list_entry(va->list.next, typeof(*va), list); } - if (!n) - return v; + if (!n && &va->list != &vmap_area_list) + return va; return NULL; @@ -2562,16 +2569,20 @@ static void *s_start(struct seq_file *m, loff_t *pos) static void *s_next(struct seq_file *m, void *p, loff_t *pos) { - struct vm_struct *v = p; + struct vmap_area *va = p, *next; ++*pos; - return v->next; + next = list_entry(va->list.next, typeof(*va), list); + if (&next->list != &vmap_area_list) + return next; + + return NULL; } static void s_stop(struct seq_file *m, void *p) - __releases(&vmlist_lock) + __releases(&vmap_area_lock) { - read_unlock(&vmlist_lock); + spin_unlock(&vmap_area_lock); } static void show_numa_info(struct seq_file *m, struct vm_struct *v) @@ -2582,6 +2593,11 @@ static void show_numa_info(struct seq_file *m, struct vm_struct *v) if (!counters) return; + /* Pair with smp_wmb() in insert_vmalloc_vmlist() */ + smp_rmb(); + if (v->flags & VM_UNLIST) + return; + memset(counters, 0, nr_node_ids * sizeof(unsigned int)); for (nr = 0; nr < v->nr_pages; nr++) @@ -2595,7 +2611,20 @@ static void show_numa_info(struct seq_file *m, struct vm_struct *v) static int s_show(struct seq_file *m, void *p) { - struct vm_struct *v = p; + struct vmap_area *va = p; + struct vm_struct *v; + + if (va->flags & (VM_LAZY_FREE | VM_LAZY_FREEING)) + return 0; + + if (!(va->flags & VM_VM_AREA)) { + seq_printf(m, "0x%pK-0x%pK %7ld vm_map_ram\n", + (void *)va->va_start, (void *)va->va_end, + va->va_end - va->va_start); + return 0; + } + + v = va->vm; seq_printf(m, "0x%pK-0x%pK %7ld", v->addr, v->addr + v->size, v->size); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/