HMM selftests are incredibly useful, but they are only effective if people actually build and run them. All the other tests in selftests/vm can be built with very standard, always-available libraries: libpthread, librt. The hmm-tests.c program, on the other hand, requires something that is (much) less readily available: libhugetlbfs. And so the build will typically fail for many developers.
A simple attempt to install libhugetlbfs will also run into complications on some common distros these days: Fedora and Arch Linux (yes, Arch AUR has it, but that's fragile, as always with AUR). The library is not maintained actively enough at the moment, for distros to deal with it. I had to build it from source, for Fedora, and that didn't go too smoothly either.
It turns out that, out of 21 tests in hmm-tests.c, only 2 actually require functionality from libhugetlbfs. Therefore, if libhugetlbfs is missing, simply ifdef those two tests out and allow the developer to at least have the other 19 tests, if they don't want to pause to work through the above issues. Also issue a warning, so that it's clear that there is an imperfection in the build.
In order to do that, a tiny shell script (check_config.sh) runs a quick compile (not link, that's too prone to false failures with library paths), and basically, if the compiler doesn't find hugetlbfs.h in its standard locations, then the script concludes that libhugetlbfs is not available. The output is in two files, one for inclusion in hmm-test.c (local_config.h), and one for inclusion in the Makefile (local_config.mk).
Signed-off-by: John Hubbard jhubbard@nvidia.com Cc: Ralph Campbell rcampbell@nvidia.com Cc: Jérôme Glisse jglisse@redhat.com Cc: Jonathan Corbet corbet@lwn.net Cc: Shuah Khan shuah@kernel.org --- tools/testing/selftests/vm/.gitignore | 1 + tools/testing/selftests/vm/Makefile | 24 +++++++++++++++-- tools/testing/selftests/vm/check_config.sh | 31 ++++++++++++++++++++++ tools/testing/selftests/vm/hmm-tests.c | 10 ++++++- 4 files changed, 63 insertions(+), 3 deletions(-) create mode 100644 tools/testing/selftests/vm/check_config.sh
diff --git a/tools/testing/selftests/vm/.gitignore b/tools/testing/selftests/vm/.gitignore index 2c8ddcf41c0e..e90d28bcd518 100644 --- a/tools/testing/selftests/vm/.gitignore +++ b/tools/testing/selftests/vm/.gitignore @@ -20,3 +20,4 @@ va_128TBswitch map_fixed_noreplace write_to_hugetlbfs hmm-tests +local_config.* diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile index 2579242386ac..a9332a7cf33f 100644 --- a/tools/testing/selftests/vm/Makefile +++ b/tools/testing/selftests/vm/Makefile @@ -1,5 +1,8 @@ # SPDX-License-Identifier: GPL-2.0 # Makefile for vm selftests + +include local_config.mk + uname_M := $(shell uname -m 2>/dev/null || echo not) MACHINE ?= $(shell echo $(uname_M) | sed -e 's/aarch64.*/arm64/')
@@ -76,8 +79,6 @@ TEST_FILES := test_vmalloc.sh KSFT_KHDR_INSTALL := 1 include ../lib.mk
-$(OUTPUT)/hmm-tests: LDLIBS += -lhugetlbfs - ifeq ($(ARCH),x86_64) BINARIES_32 := $(patsubst %,$(OUTPUT)/%,$(BINARIES_32)) BINARIES_64 := $(patsubst %,$(OUTPUT)/%,$(BINARIES_64)) @@ -130,3 +131,22 @@ endif $(OUTPUT)/mlock-random-test: LDLIBS += -lcap
$(OUTPUT)/gup_test: ../../../../mm/gup_test.h + +$(OUTPUT)/hmm-tests: local_config.h + +# HMM_EXTRA_LIBS may get set in local_config.mk, or it may be left empty. +$(OUTPUT)/hmm-tests: LDLIBS += $(HMM_EXTRA_LIBS) + +local_config.mk local_config.h: check_config.sh + /bin/sh ./check_config.sh $(CC) + +EXTRA_CLEAN += local_config.mk local_config.h + +ifeq ($(HMM_EXTRA_LIBS),) +all: warn_missing_hugelibs + +warn_missing_hugelibs: + @echo ; \ + echo "Warning: missing libhugetlbfs support. Some HMM tests will be skipped." ; \ + echo +endif diff --git a/tools/testing/selftests/vm/check_config.sh b/tools/testing/selftests/vm/check_config.sh new file mode 100644 index 000000000000..079c8a40b85d --- /dev/null +++ b/tools/testing/selftests/vm/check_config.sh @@ -0,0 +1,31 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# +# Probe for libraries and create header files to record the results. Both C +# header files and Makefile include fragments are created. + +OUTPUT_H_FILE=local_config.h +OUTPUT_MKFILE=local_config.mk + +# libhugetlbfs +tmpname=$(mktemp) +tmpfile_c=${tmpname}.c +tmpfile_o=${tmpname}.o + +echo "#include <sys/types.h>" > $tmpfile_c +echo "#include <hugetlbfs.h>" >> $tmpfile_c +echo "int func(void) { return 0; }" >> $tmpfile_c + +CC=${1:?"Usage: $0 <compiler> # example compiler: gcc"} +$CC -c $tmpfile_c -o $tmpfile_o >/dev/null 2>&1 + +if [ -f $tmpfile_o ]; then + echo "#define LOCAL_CONFIG_HAVE_LIBHUGETLBFS 1" > $OUTPUT_H_FILE + echo "HMM_EXTRA_LIBS = -lhugetlbfs" > $OUTPUT_MKFILE +else + echo "// No libhugetlbfs support found" > $OUTPUT_H_FILE + echo "# No libhugetlbfs support found, so:" > $OUTPUT_MKFILE + echo "HMM_EXTRA_LIBS = " >> $OUTPUT_MKFILE +fi + +rm ${tmpname}.* diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c index c9404ef9698e..5d1ac691b9f4 100644 --- a/tools/testing/selftests/vm/hmm-tests.c +++ b/tools/testing/selftests/vm/hmm-tests.c @@ -21,12 +21,16 @@ #include <strings.h> #include <time.h> #include <pthread.h> -#include <hugetlbfs.h> #include <sys/types.h> #include <sys/stat.h> #include <sys/mman.h> #include <sys/ioctl.h>
+#include "./local_config.h" +#ifdef LOCAL_CONFIG_HAVE_LIBHUGETLBFS +#include <hugetlbfs.h> +#endif + /* * This is a private UAPI to the kernel test module so it isn't exported * in the usual include/uapi/... directory. @@ -662,6 +666,7 @@ TEST_F(hmm, anon_write_huge) hmm_buffer_free(buffer); }
+#ifdef LOCAL_CONFIG_HAVE_LIBHUGETLBFS /* * Write huge TLBFS page. */ @@ -720,6 +725,7 @@ TEST_F(hmm, anon_write_hugetlbfs) buffer->ptr = NULL; hmm_buffer_free(buffer); } +#endif /* LOCAL_CONFIG_HAVE_LIBHUGETLBFS */
/* * Read mmap'ed file memory. @@ -1336,6 +1342,7 @@ TEST_F(hmm2, snapshot) hmm_buffer_free(buffer); }
+#ifdef LOCAL_CONFIG_HAVE_LIBHUGETLBFS /* * Test the hmm_range_fault() HMM_PFN_PMD flag for large pages that * should be mapped by a large page table entry. @@ -1411,6 +1418,7 @@ TEST_F(hmm, compound) buffer->ptr = NULL; hmm_buffer_free(buffer); } +#endif /* LOCAL_CONFIG_HAVE_LIBHUGETLBFS */
/* * Test two devices reading the same memory (double mapped).