| Message ID | 20220309014705.1265861-4-liupeng256@huawei.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 3cb1c9620eeeb67c614c0732a35861b0b1efdc53 |
| Headers | show |
| Series | kunit: fix a UAF bug and do some optimization | expand |
On 3/8/22 6:47 PM, Peng Liu wrote: > When CONFIG_KFENCE_DYNAMIC_OBJECTS is set to a big number, kfence > kunit-test-case test_gfpzero will eat up nearly all the CPU's > resources and rcu_stall is reported as the following log which is > cut from a physical server. > > rcu: INFO: rcu_sched self-detected stall on CPU > rcu: 68-....: (14422 ticks this GP) idle=6ce/1/0x4000000000000002 > softirq=592/592 fqs=7500 (t=15004 jiffies g=10677 q=20019) > Task dump for CPU 68: > task:kunit_try_catch state:R running task > stack: 0 pid: 9728 ppid: 2 flags:0x0000020a > Call trace: > dump_backtrace+0x0/0x1e4 > show_stack+0x20/0x2c > sched_show_task+0x148/0x170 > ... > rcu_sched_clock_irq+0x70/0x180 > update_process_times+0x68/0xb0 > tick_sched_handle+0x38/0x74 > ... > gic_handle_irq+0x78/0x2c0 > el1_irq+0xb8/0x140 > kfree+0xd8/0x53c > test_alloc+0x264/0x310 [kfence_test] > test_gfpzero+0xf4/0x840 [kfence_test] > kunit_try_run_case+0x48/0x20c > kunit_generic_run_threadfn_adapter+0x28/0x34 > kthread+0x108/0x13c > ret_from_fork+0x10/0x18 > > To avoid rcu_stall and unacceptable latency, a schedule point is > added to test_gfpzero. > > Signed-off-by: Peng Liu <liupeng256@huawei.com> > --- > mm/kfence/kfence_test.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/kfence/kfence_test.c b/mm/kfence/kfence_test.c > index caed6b4eba94..1b50f70a4c0f 100644 > --- a/mm/kfence/kfence_test.c > +++ b/mm/kfence/kfence_test.c > @@ -627,6 +627,7 @@ static void test_gfpzero(struct kunit *test) > kunit_warn(test, "giving up ... cannot get same object back\n"); > return; > } > + cond_resched(); This sounds like a band-aid - is there a better way to fix this? > } > > for (i = 0; i < size; i++) > thanks, -- Shuah
diff --git a/mm/kfence/kfence_test.c b/mm/kfence/kfence_test.c index caed6b4eba94..1b50f70a4c0f 100644 --- a/mm/kfence/kfence_test.c +++ b/mm/kfence/kfence_test.c @@ -627,6 +627,7 @@ static void test_gfpzero(struct kunit *test) kunit_warn(test, "giving up ... cannot get same object back\n"); return; } + cond_resched(); } for (i = 0; i < size; i++)
When CONFIG_KFENCE_DYNAMIC_OBJECTS is set to a big number, kfence kunit-test-case test_gfpzero will eat up nearly all the CPU's resources and rcu_stall is reported as the following log which is cut from a physical server. rcu: INFO: rcu_sched self-detected stall on CPU rcu: 68-....: (14422 ticks this GP) idle=6ce/1/0x4000000000000002 softirq=592/592 fqs=7500 (t=15004 jiffies g=10677 q=20019) Task dump for CPU 68: task:kunit_try_catch state:R running task stack: 0 pid: 9728 ppid: 2 flags:0x0000020a Call trace: dump_backtrace+0x0/0x1e4 show_stack+0x20/0x2c sched_show_task+0x148/0x170 ... rcu_sched_clock_irq+0x70/0x180 update_process_times+0x68/0xb0 tick_sched_handle+0x38/0x74 ... gic_handle_irq+0x78/0x2c0 el1_irq+0xb8/0x140 kfree+0xd8/0x53c test_alloc+0x264/0x310 [kfence_test] test_gfpzero+0xf4/0x840 [kfence_test] kunit_try_run_case+0x48/0x20c kunit_generic_run_threadfn_adapter+0x28/0x34 kthread+0x108/0x13c ret_from_fork+0x10/0x18 To avoid rcu_stall and unacceptable latency, a schedule point is added to test_gfpzero. Signed-off-by: Peng Liu <liupeng256@huawei.com> --- mm/kfence/kfence_test.c | 1 + 1 file changed, 1 insertion(+)