| Message ID | 20240827-patches-below_hint_mmap-v1-16-46ff2eb9022d@rivosinc.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: Introduce MAP_BELOW_HINT | expand |
On Tue, Aug 27, 2024 at 10:49:22PM GMT, Charlie Jenkins wrote: > Add a selftest for MAP_BELOW_HINT that maps until it runs out of space > below the hint address. > > Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> > --- > tools/testing/selftests/mm/Makefile | 1 + > tools/testing/selftests/mm/map_below_hint.c | 29 +++++++++++++++++++++++++++++ > 2 files changed, 30 insertions(+) > > diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile > index cfad627e8d94..4e2de85267b5 100644 > --- a/tools/testing/selftests/mm/Makefile > +++ b/tools/testing/selftests/mm/Makefile > @@ -50,6 +50,7 @@ TEST_GEN_FILES += hugepage-shm > TEST_GEN_FILES += hugepage-vmemmap > TEST_GEN_FILES += khugepaged > TEST_GEN_FILES += madv_populate > +TEST_GEN_FILES += map_below_hint > TEST_GEN_FILES += map_fixed_noreplace > TEST_GEN_FILES += map_hugetlb > TEST_GEN_FILES += map_populate > diff --git a/tools/testing/selftests/mm/map_below_hint.c b/tools/testing/selftests/mm/map_below_hint.c > new file mode 100644 > index 000000000000..305274c5af49 > --- /dev/null > +++ b/tools/testing/selftests/mm/map_below_hint.c > @@ -0,0 +1,29 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Test the MAP_BELOW_HINT mmap flag. > + */ > +#include <sys/mman.h> > +#include "../kselftest.h" > + > +#define ADDR 0x1000000UL > +#define LENGTH (ADDR / 100) > + > +#define MAP_BELOW_HINT 0x8000000 /* Not defined in all libc */ > + > +/* > + * Map memory with MAP_BELOW_HINT until no memory left. Ensure that all returned > + * addresses are below the hint. > + */ > +int main(int argc, char **argv) > +{ > + void *addr; > + > + do { > + addr = mmap((void *)ADDR, LENGTH, MAP_ANONYMOUS, MAP_BELOW_HINT, -1, 0); How can this be correct? mmap() has parameters: void *mmap(void addr[.length], size_t length, int prot, int flags, int fd, off_t offset); You'r setting prot = MAP_ANONYMOUS, flags = MAP_BELOW_HINT... This surely should be: mmap(..., PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE | MAP_BELOW_HINT, -1, 0); > + } while (addr == MAP_FAILED && (unsigned long)addr <= ADDR); How can addr == MAP_FAILED (i.e. ~0) and addr <= ADDR? This will just loop through once... If you want to make sure you're getting mappings only below the hint until you start getting MAP_FAILED's you'll need to handle this more robustly. > + > + if (addr != MAP_FAILED && (unsigned long)addr > ADDR) > + ksft_exit_fail_msg("mmap returned address above hint with MAP_BELOW_HINT\n"); This is just going to fail because your flags are wrong then wrongly claim to have passed... > + > + ksft_test_result_pass("MAP_BELOW_HINT works\n"); > +} > > -- > 2.45.0 >
On Wed, Aug 28, 2024 at 06:48:33PM +0100, Lorenzo Stoakes wrote: > On Tue, Aug 27, 2024 at 10:49:22PM GMT, Charlie Jenkins wrote: > > Add a selftest for MAP_BELOW_HINT that maps until it runs out of space > > below the hint address. > > > > Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> > > --- > > tools/testing/selftests/mm/Makefile | 1 + > > tools/testing/selftests/mm/map_below_hint.c | 29 +++++++++++++++++++++++++++++ > > 2 files changed, 30 insertions(+) > > > > diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile > > index cfad627e8d94..4e2de85267b5 100644 > > --- a/tools/testing/selftests/mm/Makefile > > +++ b/tools/testing/selftests/mm/Makefile > > @@ -50,6 +50,7 @@ TEST_GEN_FILES += hugepage-shm > > TEST_GEN_FILES += hugepage-vmemmap > > TEST_GEN_FILES += khugepaged > > TEST_GEN_FILES += madv_populate > > +TEST_GEN_FILES += map_below_hint > > TEST_GEN_FILES += map_fixed_noreplace > > TEST_GEN_FILES += map_hugetlb > > TEST_GEN_FILES += map_populate > > diff --git a/tools/testing/selftests/mm/map_below_hint.c b/tools/testing/selftests/mm/map_below_hint.c > > new file mode 100644 > > index 000000000000..305274c5af49 > > --- /dev/null > > +++ b/tools/testing/selftests/mm/map_below_hint.c > > @@ -0,0 +1,29 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * Test the MAP_BELOW_HINT mmap flag. > > + */ > > +#include <sys/mman.h> > > +#include "../kselftest.h" > > + > > +#define ADDR 0x1000000UL > > +#define LENGTH (ADDR / 100) > > + > > +#define MAP_BELOW_HINT 0x8000000 /* Not defined in all libc */ > > + > > +/* > > + * Map memory with MAP_BELOW_HINT until no memory left. Ensure that all returned > > + * addresses are below the hint. > > + */ > > +int main(int argc, char **argv) > > +{ > > + void *addr; > > + > > + do { > > + addr = mmap((void *)ADDR, LENGTH, MAP_ANONYMOUS, MAP_BELOW_HINT, -1, 0); > > How can this be correct? mmap() has parameters: > > void *mmap(void addr[.length], size_t length, int prot, int flags, > int fd, off_t offset); > > You'r setting prot = MAP_ANONYMOUS, flags = MAP_BELOW_HINT... > > This surely should be: > > mmap(..., PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE | MAP_BELOW_HINT, -1, 0); > > > + } while (addr == MAP_FAILED && (unsigned long)addr <= ADDR); > > How can addr == MAP_FAILED (i.e. ~0) and addr <= ADDR? This will just loop > through once... > > If you want to make sure you're getting mappings only below the hint until > you start getting MAP_FAILED's you'll need to handle this more robustly. > > > + > > + if (addr != MAP_FAILED && (unsigned long)addr > ADDR) > > + ksft_exit_fail_msg("mmap returned address above hint with MAP_BELOW_HINT\n"); > > This is just going to fail because your flags are wrong then wrongly claim > to have passed... I obviously didn't spend enough time thinking about this test case... You are correct that I wrote this incorrectly. I will make a proper test case and send out a new version. - Charlie > > > + > > + ksft_test_result_pass("MAP_BELOW_HINT works\n"); > > +} > > > > -- > > 2.45.0 > >
diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile index cfad627e8d94..4e2de85267b5 100644 --- a/tools/testing/selftests/mm/Makefile +++ b/tools/testing/selftests/mm/Makefile @@ -50,6 +50,7 @@ TEST_GEN_FILES += hugepage-shm TEST_GEN_FILES += hugepage-vmemmap TEST_GEN_FILES += khugepaged TEST_GEN_FILES += madv_populate +TEST_GEN_FILES += map_below_hint TEST_GEN_FILES += map_fixed_noreplace TEST_GEN_FILES += map_hugetlb TEST_GEN_FILES += map_populate diff --git a/tools/testing/selftests/mm/map_below_hint.c b/tools/testing/selftests/mm/map_below_hint.c new file mode 100644 index 000000000000..305274c5af49 --- /dev/null +++ b/tools/testing/selftests/mm/map_below_hint.c @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Test the MAP_BELOW_HINT mmap flag. + */ +#include <sys/mman.h> +#include "../kselftest.h" + +#define ADDR 0x1000000UL +#define LENGTH (ADDR / 100) + +#define MAP_BELOW_HINT 0x8000000 /* Not defined in all libc */ + +/* + * Map memory with MAP_BELOW_HINT until no memory left. Ensure that all returned + * addresses are below the hint. + */ +int main(int argc, char **argv) +{ + void *addr; + + do { + addr = mmap((void *)ADDR, LENGTH, MAP_ANONYMOUS, MAP_BELOW_HINT, -1, 0); + } while (addr == MAP_FAILED && (unsigned long)addr <= ADDR); + + if (addr != MAP_FAILED && (unsigned long)addr > ADDR) + ksft_exit_fail_msg("mmap returned address above hint with MAP_BELOW_HINT\n"); + + ksft_test_result_pass("MAP_BELOW_HINT works\n"); +}
Add a selftest for MAP_BELOW_HINT that maps until it runs out of space below the hint address. Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> --- tools/testing/selftests/mm/Makefile | 1 + tools/testing/selftests/mm/map_below_hint.c | 29 +++++++++++++++++++++++++++++ 2 files changed, 30 insertions(+)