Merge branch 'error-injection'

Masami Hiramatsu says:

====================
Here are the 5th version of patches to moving error injection
table from kprobes. This version fixes a bug and update
fail-function to support multiple function error injection.

Here is the previous version:

https://patchwork.ozlabs.org/cover/858663/

Changes in v5:
 - [3/5] Fix a bug that within_error_injection returns false always.
 - [5/5] Update to support multiple function error injection.

Thank you,
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Signed-off-by: Alexei Starovoitov <ast@kernel.org>