Re: [PATCH v3 1/3] vmalloc: Choose a better start address in vm_area_register_early()
From: Kefeng Wang
Date: Fri Aug 27 2021 - 04:36:33 EST
On 2021/8/26 1:59, Catalin Marinas wrote:
On Mon, Aug 09, 2021 at 05:37:48PM +0800, Kefeng Wang wrote:
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d5cd52805149..1e8fe08725b8 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2238,11 +2238,17 @@ void __init vm_area_add_early(struct vm_struct *vm)
*/
void __init vm_area_register_early(struct vm_struct *vm, size_t align)
{
- static size_t vm_init_off __initdata;
- unsigned long addr;
-
- addr = ALIGN(VMALLOC_START + vm_init_off, align);
- vm_init_off = PFN_ALIGN(addr + vm->size) - VMALLOC_START;
+ struct vm_struct *head = vmlist, *curr, *next;
+ unsigned long addr = ALIGN(VMALLOC_START, align);
+
+ while (head != NULL) {
Nitpick: I'd use the same pattern as in vm_area_add_early(), i.e. a
'for' loop. You might as well insert it directly than calling the add
function and going through the loop again. Not a strong preference
either way.
+ next = head->next;
+ curr = head;
+ head = next;
+ addr = ALIGN((unsigned long)curr->addr + curr->size, align);
+ if (next && (unsigned long)next->addr - addr > vm->size)
Is greater or equal sufficient?
+ break;
+ }
vm->addr = (void *)addr;
Another nitpick: it's very unlikely on a 64-bit architecture but not
impossible on 32-bit to hit VMALLOC_END here. Maybe some BUG_ON.
Hi Catalin, thank for your review, I will update in the next version,
Could you take a look the following change, is it OK?
void __init vm_area_register_early(struct vm_struct *vm, size_t align)
{
struct vm_struct *next, *cur, **p;
unsigned long addr = ALIGN(VMALLOC_START, align);
BUG_ON(vmap_initialized);
for (p = &vmlist; (cur = *p) != NULL, next = cur->next; p =
&next) {
addr = ALIGN((unsigned long)cur->addr + cur->size,
align);
if (next && (unsigned long)next->addr - addr >=
vm->size) {
p = &next;
break;
}
}
BUG_ON(addr > VMALLOC_END - vm->size);
vm->addr = (void *)addr;
vm->next = *p;
*p = vm;
}