Re: WARNING in kvmalloc_node

[Daniel Borkmann]

[ +Jason, +Jesper ]

On 02/14/2018 09:43 AM, Michal Hocko wrote:
> On Tue 13-02-18 18:55:33, Matthew Wilcox wrote:
>> On Tue, Feb 13, 2018 at 03:59:01PM -0800, syzbot wrote:
> [...]
>>>  kvmalloc include/linux/mm.h:541 [inline]
>>>  kvmalloc_array include/linux/mm.h:557 [inline]
>>>  __ptr_ring_init_queue_alloc include/linux/ptr_ring.h:474 [inline]
>>>  ptr_ring_init include/linux/ptr_ring.h:492 [inline]
>>>  __cpu_map_entry_alloc kernel/bpf/cpumap.c:359 [inline]
>>>  cpu_map_update_elem+0x3c3/0x8e0 kernel/bpf/cpumap.c:490
>>>  map_update_elem kernel/bpf/syscall.c:698 [inline]
>>
>> Blame the BPF people, not the MM people ;-)

Heh, not really. ;-)

> Yes. kvmalloc (the vmalloc part) doesn't support GFP_ATOMIC semantic.

Agree, that doesn't work.

Bug was added in commit 0bf7800f1799 ("ptr_ring: try vmalloc() when kmalloc() fails").

Jason, please take a look at fixing this, thanks!