| Message ID | 20250110-virtual_address_range-tests-v2-1-262a2bf3c3d0@linutronix.de (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | selftests/mm: virtual_address_range: Reduce memory usage and avoid VVAR access | expand |
On 10.01.25 14:05, Thomas Weißschuh wrote: > When mapping a larger chunk than physical memory is available with > PROT_WRITE and overcommit is disabled, the mapping will fail. > This will prevent the test from running on systems with less then ~1GiB > of memory and triggering an inscrutinable test failure. > As the mappings are never written to anyways, the flag can be removed. > > Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()") > Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> > > --- > I went with dropping PROT_WRITE instead of adding MAP_NORESERVE as this > works even in the face of OVERCOMMIT_NEVER. Yes, makes sense, it's certainly simpler this way. Acked-by: David Hildenbrand <david@redhat.com>
On 10/01/25 6:35 pm, Thomas Weißschuh wrote: > When mapping a larger chunk than physical memory is available with > PROT_WRITE and overcommit is disabled, the mapping will fail. > This will prevent the test from running on systems with less then ~1GiB > of memory and triggering an inscrutinable test failure. > As the mappings are never written to anyways, the flag can be removed. > > Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()") > Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Thanks! FWIW: Acked-by: Dev Jain <dev.jain@arm.com>
diff --git a/tools/testing/selftests/mm/virtual_address_range.c b/tools/testing/selftests/mm/virtual_address_range.c index 2a2b69e91950a37999f606847c9c8328d79890c2..ea6ccf49ef4c552f26317c2a40b09bca1a677f8f 100644 --- a/tools/testing/selftests/mm/virtual_address_range.c +++ b/tools/testing/selftests/mm/virtual_address_range.c @@ -166,7 +166,7 @@ int main(int argc, char *argv[]) ksft_set_plan(1); for (i = 0; i < NR_CHUNKS_LOW; i++) { - ptr[i] = mmap(NULL, MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE, + ptr[i] = mmap(NULL, MAP_CHUNK_SIZE, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (ptr[i] == MAP_FAILED) { @@ -186,7 +186,7 @@ int main(int argc, char *argv[]) for (i = 0; i < NR_CHUNKS_HIGH; i++) { hint = hint_addr(); - hptr[i] = mmap(hint, MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE, + hptr[i] = mmap(hint, MAP_CHUNK_SIZE, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (hptr[i] == MAP_FAILED)
When mapping a larger chunk than physical memory is available with PROT_WRITE and overcommit is disabled, the mapping will fail. This will prevent the test from running on systems with less then ~1GiB of memory and triggering an inscrutinable test failure. As the mappings are never written to anyways, the flag can be removed. Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()") Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> --- I went with dropping PROT_WRITE instead of adding MAP_NORESERVE as this works even in the face of OVERCOMMIT_NEVER. --- tools/testing/selftests/mm/virtual_address_range.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)