Commit f3a45709 authored by John Hubbard's avatar John Hubbard Committed by Linus Torvalds

selftests/vm: hmm-tests: remove the libhugetlbfs dependency

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).

Link: https://lkml.kernel.org/r/20201026064021.3545418-9-jhubbard@nvidia.comSigned-off-by: default avatarJohn 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>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d943fe81
......@@ -20,3 +20,4 @@ va_128TBswitch
map_fixed_noreplace
write_to_hugetlbfs
hmm-tests
local_config.*
# 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/')
......@@ -80,8 +83,6 @@ 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))
......@@ -134,3 +135,22 @@ 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
#!/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}.*
......@@ -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).
......
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