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cc: linux-kernel@vger.kernel.org, linux-mm@vger.kernel.org
Subject: next-20160314 - KASAN breaks 'make C=2' build...
From: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
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Date: Tue, 15 Mar 2016 05:11:20 -0400
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This config breaks sparse:

grep KASAN .config
CONFIG_KASAN_SHADOW_OFFSET=0xdffffc0000000000
CONFIG_HAVE_ARCH_KASAN=y
CONFIG_KASAN=y
# CONFIG_KASAN_OUTLINE is not set
CONFIG_KASAN_INLINE=y
CONFIG_TEST_KASAN=m

 LANG=C make C=2
  CHK     include/config/kernel.release
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
  CHK     include/generated/bounds.h
  CHK     include/generated/timeconst.h
  CHK     include/generated/asm-offsets.h
  CALL    scripts/checksyscalls.sh
  DESCEND  objtool
  CHECK   scripts/mod/empty.c
No such file: asan-stack=1
scripts/Makefile.build:291: recipe for target 'scripts/mod/empty.o' failed
make[2]: *** [scripts/mod/empty.o] Error 1
scripts/Makefile.build:440: recipe for target 'scripts/mod' failed
make[1]: *** [scripts/mod] Error 2
Makefile:552: recipe for target 'scripts' failed
make: *** [scripts] Error 2

Looks like it's this chunk from scripts/Makefile.kasan:

CFLAGS_KASAN := $(call cc-option, -fsanitize=kernel-address 
                -fasan-shadow-offset=$(KASAN_SHADOW_OFFSET) 
                --param asan-stack=1 --param asan-globals=1 
                --param asan-instrumentation-with-call-threshold=$(call_threshold))

4AM is a bad time to figure out who's to blame here....