Messages in this thread Patch in this message | | | From | Guanghui Feng <> | Subject | [PATCH] printk: fix softlockup/rcu stall warning without setting CONFIG_PREEMPTION | Date | Sat, 12 Feb 2022 21:27:42 +0800 |
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If without setting CONFIG_PREEMPTION, and there are too many messages only in one cpu which will set console_may_schedule to 0 without cond_resched, we will find softlockup/rcu stall warning. Although the timer interrupt can be raised in the routine of console_unlock, the irq interrupt return to user/kernel will't schedule other tasks(without setting CONFIG_PREEMPTION). So I add need_resched() for cond_schedule to avoid it.
Call trace: console_unlock+0x220/0x420 vprintk_emit+0x17c/0x1ac vprintk_default+0x3c/0x44 vprintk+0x38/0x70 printk+0x64/0x88 dump_task.part.0+0xc4/0xe0 dump_task+0x70/0x74 dump_tasks+0x78/0x90 dump_global_header+0xcc/0xe8 oom_kill_process+0x258/0x274 out_of_memory.part.0+0xb0/0x33c out_of_memory+0x4c/0xa0 __alloc_pages_may_oom+0x11c/0x1a0 __alloc_pages_slowpath.constprop.0+0x4c0/0x75c __alloc_pages_nodemask+0x2b4/0x310 alloc_pages_current+0x8c/0x140 get_zeroed_page+0x20/0x50 __pud_alloc+0x40/0x190 copy_pud_range+0x264/0x280 copy_page_range+0xe8/0x204 dup_mmap+0x334/0x434 dup_mm+0x64/0x11c copy_process+0x5e0/0x11a0 kernel_clone+0x94/0x364 __do_sys_clone+0x54/0x80 __arm64_sys_clone+0x24/0x30 el0_svc_common.constprop.0+0x7c/0x210 do_el0_svc+0x74/0x90 el0_svc+0x24/0x60 el0_sync_handler+0xa8/0xb0 el0_sync+0x140/0x180
Signed-off-by: Guanghui Feng <guanghuifeng@linux.alibaba.com> --- kernel/printk/printk.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 82abfaf..54b6cf2 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2716,7 +2716,11 @@ void console_unlock(void) if (handover) return; +#ifndef CONFIG_PREEMPTION + if (do_cond_resched || need_resched()) +#else if (do_cond_resched) +#endif cond_resched(); } -- 1.8.3.1
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