On Thu, Jun 9, 2022 at 3:26 AM Catalin Marinas <catalin.marinas@xxxxxxx> wrote: > > On Thu, Jun 09, 2022 at 11:11:54AM +0100, Will Deacon wrote: > > On Thu, Jun 09, 2022 at 11:44:09AM +0800, Kefeng Wang wrote: > > > On 2022/6/9 10:49, Vasily Averin wrote: > > > > mem_cgroup_from_obj(): > > > > ffff80000836cf40: d503245f bti c > > > > ffff80000836cf44: d503201f nop > > > > ffff80000836cf48: d503201f nop > > > > ffff80000836cf4c: d503233f paciasp > > > > ffff80000836cf50: d503201f nop > > > > ffff80000836cf54: d2e00021 mov x1, #0x1000000000000 // #281474976710656 > > > > ffff80000836cf58: 8b010001 add x1, x0, x1 > > > > ffff80000836cf5c: b25657e4 mov x4, #0xfffffc0000000000 // #-4398046511104 > > > > ffff80000836cf60: d34cfc21 lsr x1, x1, #12 > > > > ffff80000836cf64: d37ae421 lsl x1, x1, #6 > > > > ffff80000836cf68: 8b040022 add x2, x1, x4 > > > > ffff80000836cf6c: f9400443 ldr x3, [x2, #8] > > > > > > > > x5 : ffff80000a96f000 x4 : fffffc0000000000 x3 : ffff80000ad5e680 > > > > x2 : fffffe00002bc240 x1 : 00000200002bc240 x0 : ffff80000af09740 > > > > > > > > x0 = 0xffff80000af09740 is an argument of mem_cgroup_from_obj() > > > > according to System.map it is init_net > > > > > > > > This issue is caused by calling virt_to_page() on address of static variable init_net. > > > > Arm64 consider that addresses of static variables are not valid virtual addresses. > > > > On x86_64 the same API works without any problem. > > > > This just depends on whether or not the kernel is running out of the linear > > mapping or not. On arm64, we use the vmalloc area for the kernel image and > > so virt_to_page() won't work, just like it won't work for modules on other > > architectures. > > > > How are module addresses handled by mem_cgroup_from_obj()? > > It doesn't look like they are handled in any way. It just expects the > pointer to be a linear map one. Yes, that is correct. > Something like below: > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 27cebaa53472..795bf3673fa7 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2860,6 +2860,11 @@ struct mem_cgroup *mem_cgroup_from_obj(void *p) > if (mem_cgroup_disabled()) > return NULL; > > + if (is_module_address((unsigned long)p)) > + return NULL; > + else if (is_kernel((unsigned long)p)) > + return NULL; > + How about just is_vmalloc_addr(p) check? It should cover modules and also arm64 using vmalloc for kernel image cases. > folio = virt_to_folio(p); > > /* > > -- > Catalin
