lkml.org 
[lkml]   [2022]   [Mar]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 1/1] mm/page_alloc: add scheduling point to free_unref_page_list
From
Date
On 03/03/2022 07:34 AM, Andrew Morton wrote:
> On Tue, 1 Mar 2022 20:38:25 -0500 wangjianxing <wangjianxing@loongson.cn> wrote:
>
>> free a large list of pages maybe cause rcu_sched starved on
>> non-preemptible kernels
>>
>> rcu: rcu_sched kthread starved for 5359 jiffies! g454793 f0x0
>> RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=19
>> [...]
>> Call Trace:
>> free_unref_page_list+0x19c/0x270
>> release_pages+0x3cc/0x498
>> tlb_flush_mmu_free+0x44/0x70
>> zap_pte_range+0x450/0x738
>> unmap_page_range+0x108/0x240
>> unmap_vmas+0x74/0xf0
>> unmap_region+0xb0/0x120
>> do_munmap+0x264/0x438
>> vm_munmap+0x58/0xa0
>> sys_munmap+0x10/0x20
>> syscall_common+0x24/0x38
> Thanks.
>
> How did this large list of pages come about?
>
> Will people be seeing this message in upstream kernels, or is it
> specific to some caller code which you have added?
>
> Please always include details such as this so that others can determine
> whether the fix should be backported into -stable kernels.
Thanks.

I try to increase the overcommit ratio of cpu to 1:2~1:3 in KVM
hypervisor, per-vm has the same number of vcpu with host cpu, then setup
2 or 3 vm.
Run ltpstress test in per vm, both host and guest is non-preemptiable
kernel, vm dmesg will throw some rcu_sched warning.

ltp version is 20180926, but until now I didn't analysis ltpstress code
deeply.

\
 
 \ /
  Last update: 2022-03-03 03:03    [W:0.349 / U:0.088 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site