On Wed, Jul 11, 2018 at 01:05:19PM +0100, Will Deacon wrote: > On Wed, Jul 11, 2018 at 07:06:28PM +0800, Yandong.Zhao wrote: > > From: Yandong Zhao <yandong77...@gmail.com> > > > > It does not matter if the caller of may_use_simd() migrates to > > another cpu after the call, but it is still important that the > > kernel_neon_busy percpu instance that is read matches the cpu the > > task is running on at the time of the read. > > > > This means that raw_cpu_read() is not sufficient. kernel_neon_busy > > may appear true if the caller migrates during the execution of > > raw_cpu_read() and the next task to be scheduled in on the initial > > cpu calls kernel_neon_begin(). > > > > This patch replaces raw_cpu_read() with this_cpu_read() to protect > > against this race. > > > > Fixes: cb84d11e1625 ("arm64: neon: Remove support for nested or hardirq > > kernel-mode NEON") > > Reviewed-by: Dave Martin <dave.mar...@arm.com> > > Signed-off-by: Yandong Zhao <yandong77...@gmail.com> > > --- > > arch/arm64/include/asm/simd.h | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > Does this need to go to stable?
It should, yes, so we should probably add Cc: sta...@vger.kernel.org Are you OK to pick that up? Cheers ---Dave