Switching to -O2 when building the mm tests has the unexpected side effect of triggering many unused-result warnings on certain distros like Ubuntu, where GCC is configured so that -O2 implies -D_FORTIFY_SOURCE. Explicitly disable FORTIFY_SOURCE to avoid those warnings. This has no effect on upstream toolchains where FORTIFY_SOURCE is not implicitly enabled. Suggested-by: Ryan Roberts <ryan.roberts@xxxxxxx> Signed-off-by: Kevin Brodsky <kevin.brodsky@xxxxxxx> --- Hi Andrew, Could you please take this fixup patch for "selftests/mm: Build with -O2" in mm-unstable? Ryan found that building the mm kselftests on Ubuntu yields a bunch of warnings, this patch suppresses them. Cheers, - Kevin Cc: aruna.ramakrishna@xxxxxxxxxx Cc: catalin.marinas@xxxxxxx Cc: dave.hansen@xxxxxxxxxxxxxxx Cc: joey.gouly@xxxxxxx Cc: keith.lucas@xxxxxxxxxx Cc: shuah@xxxxxxxxxx Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx Cc: linux-kselftest@xxxxxxxxxxxxxxx Cc: linux-mm@xxxxxxxxx Cc: x86@xxxxxxxxxx --- tools/testing/selftests/mm/Makefile | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile index fce194a92cad..d633d6b6a6e1 100644 --- a/tools/testing/selftests/mm/Makefile +++ b/tools/testing/selftests/mm/Makefile @@ -36,6 +36,13 @@ MAKEFLAGS += --no-builtin-rules CFLAGS = -Wall -O2 -I $(top_srcdir) $(EXTRA_CFLAGS) $(KHDR_INCLUDES) $(TOOLS_INCLUDES) LDLIBS = -lrt -lpthread -lm +# Some distributions (such as Ubuntu) configure GCC so that _FORTIFY_SOURCE is +# automatically enabled at -O1 or above. This triggers various unused-result +# warnings where functions such as read() or write() are called and their +# return value is not checked. Disable _FORTIFY_SOURCE to silence those +# warnings. +CFLAGS += -U_FORTIFY_SOURCE + KDIR ?= /lib/modules/$(shell uname -r)/build ifneq (,$(wildcard $(KDIR)/Module.symvers)) ifneq (,$(wildcard $(KDIR)/include/linux/page_frag_cache.h)) -- 2.47.0
