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

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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>
This commit is contained in:
Audra Mitchell 2025-12-01 13:18:48 -05:00 • committed by Andrew Morton
parent bd4526e64b
commit a98ec863fd
2 changed files with 35 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

11
lib/test_vmalloc.c
View file

@ -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);

31
tools/testing/selftests/mm/test_vmalloc.sh
View file

@ -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."
}