igt/drv_suspend: Suspend under memory pressure

Recently we discovered that we have a race between swapping and
suspend in our resume path (we might be trying to page in an object
after disabling the block devices). Let's try to exercise that by
exhausting all of system memory before suspend.

v2: Explicitly share the large memory area on forking to avoid running
out of memory inside the suspend helpers (for they fork!)

References: https://bugs.freedesktop.org/show_bug.cgi?id=106640
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tomi Sarvela <tomi.p.sarvela@intel.com>
Reviewed-by: Antonio Argenziano <antonio.argenziano@intel.com>

1 files changed, 54 insertions, 0 deletions

diff --git a/tests/drv_suspend.c b/tests/drv_suspend.c
index 2e39f20a..9a9ff200 100644
--- a/tests/drv_suspend.c
+++ b/tests/drv_suspend.c
@@ -161,6 +161,57 @@ test_sysfs_reader(bool hibernate)
 }
 
 static void
+test_shrink(int fd, unsigned int mode)
+{
+	uint64_t *can_mlock, pin;
+
+	gem_quiescent_gpu(fd);
+	intel_purge_vm_caches(fd);
+
+	pin = (intel_get_total_ram_mb() + 1) << 20;
+
+	igt_debug("Total memory %'"PRIu64" B (%'"PRIu64" MiB)\n",
+		  pin, pin >> 20);
+	can_mlock = mmap(NULL, pin, PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
+	igt_require(can_mlock != MAP_FAILED);
+
+	/* Lock all the system memory, forcing the driver into swap and OOM */
+	for (uint64_t inc = 64 << 20; inc >= 4 << 10; inc >>= 1) {
+		igt_debug("Testing+ %'"PRIu64" B (%'"PRIu64" MiB)\n",
+			  *can_mlock, *can_mlock >> 20);
+
+		igt_fork(child, 1) {
+			for (uint64_t bytes = *can_mlock;
+			     bytes <= pin;
+			     bytes += inc) {
+				if (mlock(can_mlock, bytes))
+					break;
+
+				*can_mlock = bytes;
+				__sync_synchronize();
+			}
+		}
+		__igt_waitchildren();
+	}
+
+	intel_purge_vm_caches(fd);
+
+	igt_require(*can_mlock > 64 << 20);
+	*can_mlock -= 64 << 20;
+
+	igt_debug("Locking %'"PRIu64" B (%'"PRIu64" MiB)\n",
+		  *can_mlock, *can_mlock >> 20);
+	igt_assert(!mlock(can_mlock, *can_mlock));
+	igt_info("Locked %'"PRIu64" B (%'"PRIu64" MiB)\n",
+		 *can_mlock, *can_mlock >> 20);
+
+	intel_purge_vm_caches(fd);
+	igt_system_suspend_autoresume(mode, SUSPEND_TEST_NONE);
+
+	munmap(can_mlock, pin);
+}
+
+static void
 test_forcewake(int fd, bool hibernate)
 {
 	int fw_fd;
@@ -199,6 +250,9 @@ igt_main
 	igt_subtest("sysfs-reader")
 		test_sysfs_reader(false);
 
+	igt_subtest("shrink")
+		test_shrink(fd, SUSPEND_STATE_MEM);
+
 	igt_subtest("forcewake")
 		test_forcewake(fd, false);