The patch titled
Subject: kfence: test: try to avoid test_gfpzero trigger rcu_stall
has been added to the -mm tree. Its filename is
kfence-test-try-to-avoid-test_gfpzero-trigger-rcu_stall.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kfence-test-try-to-avoid-test_gfpzero-trigger-rcu_stall.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kfence-test-try-to-avoid-test_gfpzero-trigger-rcu_stall.patch
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------------------------------------------------------
From: Peng Liu <liupeng256@xxxxxxxxxx>
Subject: kfence: test: try to avoid test_gfpzero trigger rcu_stall
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@xxxxxxxxxx
Signed-off-by: Peng Liu <liupeng256@xxxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Brendan Higgins <brendanhiggins@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Wang Kefeng <wangkefeng.wang@xxxxxxxxxx>
Cc: Daniel Latypov <dlatypov@xxxxxxxxxx>
Cc: David Gow <davidgow@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kfence/kfence_test.c | 1 +
1 file changed, 1 insertion(+)
--- a/mm/kfence/kfence_test.c~kfence-test-try-to-avoid-test_gfpzero-trigger-rcu_stall
+++ a/mm/kfence/kfence_test.c
@@ -627,6 +627,7 @@ static void test_gfpzero(struct kunit *t
kunit_warn(test, "giving up ... cannot get same object back\n");
return;
}
+ cond_resched();
}
for (i = 0; i < size; i++)
_
Patches currently in -mm which might be from liupeng256@xxxxxxxxxx are
kunit-fix-uaf-when-run-kfence-test-case-test_gfpzero.patch
kunit-make-kunit_test_timeout-compatible-with-comment.patch
kfence-test-try-to-avoid-test_gfpzero-trigger-rcu_stall.patch
