On 6/7/22 08:58, Shakeel Butt wrote: > On Mon, Jun 6, 2022 at 11:45 AM Vasily Averin <vvs@xxxxxxxxxx> wrote: >> > [...] >> >> As far as I understand this report means that 'init_net' have incorrect >> virtual address on arm64. > > So, the two call stacks tell the addresses belong to the kernel > modules (nfnetlink and nf_tables) whose underlying memory is allocated > through vmalloc and virt_to_page() does not work on vmalloc() > addresses. However in both these cases get_mem_cgroup_from_obj() -> mem_cgroup_from_obj() -> virt_to_folio() -> virt_to_page() -> virt_to_pfn() -> __virt_to_phys() handles address of struct net taken from for_each_net(). The only net namespace that exists at this stage is init_net, and dmesg output confirms this: "virt_to_phys used for non-linear address: ffffd8efe2d2fe00 (init_net)" >> Roman, Shakeel, I need your help >> >> Should we perhaps verify kaddr via virt_addr_valid() before using virt_to_page() >> If so, where it should be checked? > > I think virt_addr_valid() check in mem_cgroup_from_obj() should work > but I think it is expensive on the arm64 platform. The cheaper and a > bit hacky way to avoid such addresses is to directly use > is_vmalloc_addr() directly. I do not understand why you mean that processed address is vmalloc-specific. As far as I understand it is valid address of static variable, and for some reason arm64 does not consider them valid virtual addresses. Thank you, Vasily Averin
