On 03/07/2018 11:33 PM, Herbert Xu wrote:
On Wed, Mar 07, 2018 at 11:24:16AM -0800, Greg Hackmann wrote:
f7c83bcbfaf5 ("net: xfrm: use __this_cpu_read per-cpu helper") added a
__this_cpu_read() call inside ipcomp_alloc_tfms(). Since this call was
introduced, the rules around per-cpu accessors have been tightened and
__this_cpu_read() cannot be used in a preemptible context.
syzkaller reported this leading to the following kernel BUG while
fuzzing sendmsg:
How about reverting f7c83bcbfaf5 instead?
Thanks,
Because that would not be nice.
this_cpu_read() is faster than going through raw_smp_processor_id() and
per_cpu_ptr()