David Hildenbrand
96ffece6c6
commitd6718941a2upstream. It's very easy to crash the kernel right now by simply trying to enable memtrace concurrently, hammering on the "enable" interface loop.sh: #!/bin/bash dmesg --console-off while true; do echo 0x40000000 > /sys/kernel/debug/powerpc/memtrace/enable done [root@localhost ~]# loop.sh & [root@localhost ~]# loop.sh & Resulting quickly in a kernel crash. Let's properly protect using a mutex. Fixes:9d5171a8f2("powerpc/powernv: Enable removal of memory for in memory tracing") Cc: stable@vger.kernel.org# v4.14+ Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20201111145322.15793-3-david@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>