From: Peng Liu liupeng256@huawei.com
mainline inclusion from mainline-v5.18-rc1 commit 3cb1c9620eeeb67c614c0732a35861b0b1efdc53 category: bugfix bugzilla: 187071, https://gitee.com/openeuler/kernel/issues/I5DLA7 CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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When CONFIG_KFENCE_NUM_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.
Link: https://lkml.kernel.org/r/20220309083753.1561921-4-liupeng256@huawei.com Signed-off-by: Peng Liu liupeng256@huawei.com Reviewed-by: Marco Elver elver@google.com Tested-by: Brendan Higgins brendanhiggins@google.com Cc: Alexander Potapenko glider@google.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Wang Kefeng wangkefeng.wang@huawei.com Cc: Daniel Latypov dlatypov@google.com Cc: David Gow davidgow@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com Reviewed-by: Kefeng Wang wangkefeng.wang@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@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 4c9a9a47c8e3..0acbc7365412 100644 --- a/mm/kfence/kfence_test.c +++ b/mm/kfence/kfence_test.c @@ -625,6 +625,7 @@ 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++)