On 2018年02月14日 17:28, Daniel Borkmann wrote:
[ +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!

It looks to me the only solution is to revert that commit.

Will post a patch.

Thanks

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