lib/test_vmalloc.c: minor fixes to test_vmalloc.c

If PAGE_SIZE is larger than 4k and if you have a system with a large
number of CPUs, this test can require a very large amount of memory
leading to oom-killer firing.  Given the type of allocation, the kernel
won't have anything to kill, causing the system to stall.

Add a parameter to the test_vmalloc driver to represent the number of
times a percpu object will be allocated.  Calculate this in
test_vmalloc.sh to be 90% of available memory or the current default of
35000, whichever is smaller.

Link: https://lkml.kernel.org/r/20251201181848.1216197-1-audra@redhat.com
Signed-off-by: Audra Mitchell <audra@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rafael Aquini <raquini@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/lib/test_vmalloc.c b/lib/test_vmalloc.c
index 6521c05c781685610b3d83bb1c408b3fa4daf40b..270b6f7ca8074c6599f25ed5ab5a3add62647710 100644 (file)
--- a/lib/test_vmalloc.c
+++ b/lib/test_vmalloc.c
@@ -58,6 +58,9 @@ __param(int, run_test_mask, 7,
                /* Add a new test case description here. */
 );
 
+__param(int, nr_pcpu_objects, 35000,
+       "Number of pcpu objects to allocate for pcpu_alloc_test");
+
 /*
  * This is for synchronization of setup phase.
  */
@@ -317,24 +320,24 @@ pcpu_alloc_test(void)
        size_t size, align;
        int i;
 
-       pcpu = vmalloc(sizeof(void __percpu *) * 35000);
+       pcpu = vmalloc(sizeof(void __percpu *) * nr_pcpu_objects);
        if (!pcpu)
                return -1;
 
-       for (i = 0; i < 35000; i++) {
+       for (i = 0; i < nr_pcpu_objects; i++) {
                size = get_random_u32_inclusive(1, PAGE_SIZE / 4);
 
                /*
                 * Maximum PAGE_SIZE
                 */
-               align = 1 << get_random_u32_inclusive(1, 11);
+               align = 1 << get_random_u32_inclusive(1, PAGE_SHIFT - 1);
 
                pcpu[i] = __alloc_percpu(size, align);
                if (!pcpu[i])
                        rv = -1;
        }
 
-       for (i = 0; i < 35000; i++)
+       for (i = 0; i < nr_pcpu_objects; i++)
                free_percpu(pcpu[i]);
 
        vfree(pcpu);

diff --git a/tools/testing/selftests/mm/test_vmalloc.sh b/tools/testing/selftests/mm/test_vmalloc.sh
index d39096723fca0f7be4713a75f245c6a7512a46cf..b23d705bf570f05180e588db34561fde1b249b5b 100755 (executable)
--- a/tools/testing/selftests/mm/test_vmalloc.sh
+++ b/tools/testing/selftests/mm/test_vmalloc.sh
@@ -13,6 +13,9 @@ TEST_NAME="vmalloc"
 DRIVER="test_${TEST_NAME}"
 NUM_CPUS=`grep -c ^processor /proc/cpuinfo`
 
+# Default number of times we allocate percpu objects:
+NR_PCPU_OBJECTS=35000
+
 # 1 if fails
 exitcode=1
 
@@ -27,6 +30,8 @@ PERF_PARAM="sequential_test_order=1 test_repeat_count=3"
 SMOKE_PARAM="test_loop_count=10000 test_repeat_count=10"
 STRESS_PARAM="nr_threads=$NUM_CPUS test_repeat_count=20"
 
+PCPU_OBJ_PARAM="nr_pcpu_objects=$NR_PCPU_OBJECTS"
+
 check_test_requirements()
 {
        uid=$(id -u)
@@ -47,12 +52,30 @@ check_test_requirements()
        fi
 }
 
+check_memory_requirement()
+{
+       # The pcpu_alloc_test allocates nr_pcpu_objects per cpu. If the
+       # PAGE_SIZE is on the larger side it is easier to set a value
+       # that can cause oom events during testing. Since we are
+       # testing the functionality of vmalloc and not the oom-killer,
+       # calculate what is 90% of available memory and divide it by
+       # the number of online CPUs.
+       pages=$(($(getconf _AVPHYS_PAGES) * 90 / 100 / $NUM_CPUS))
+
+       if (($pages < $NR_PCPU_OBJECTS)); then
+               echo "Updated nr_pcpu_objects to 90% of available memory."
+               echo "nr_pcpu_objects is now set to: $pages."
+               PCPU_OBJ_PARAM="nr_pcpu_objects=$pages"
+       fi
+}
+
 run_performance_check()
 {
        echo "Run performance tests to evaluate how fast vmalloc allocation is."
        echo "It runs all test cases on one single CPU with sequential order."
 
-       modprobe $DRIVER $PERF_PARAM > /dev/null 2>&1
+       check_memory_requirement
+       modprobe $DRIVER $PERF_PARAM $PCPU_OBJ_PARAM > /dev/null 2>&1
        echo "Done."
        echo "Check the kernel message buffer to see the summary."
 }
@@ -63,7 +86,8 @@ run_stability_check()
        echo "available test cases are run by NUM_CPUS workers simultaneously."
        echo "It will take time, so be patient."
 
-       modprobe $DRIVER $STRESS_PARAM > /dev/null 2>&1
+       check_memory_requirement
+       modprobe $DRIVER $STRESS_PARAM $PCPU_OBJ_PARAM > /dev/null 2>&1
        echo "Done."
        echo "Check the kernel ring buffer to see the summary."
 }
@@ -74,7 +98,8 @@ run_smoke_check()
        echo "Please check $0 output how it can be used"
        echo "for deep performance analysis as well as stress testing."
 
-       modprobe $DRIVER $SMOKE_PARAM > /dev/null 2>&1
+       check_memory_requirement
+       modprobe $DRIVER $SMOKE_PARAM $PCPU_OBJ_PARAM > /dev/null 2>&1
        echo "Done."
        echo "Check the kernel ring buffer to see the summary."
 }