13 Jan
2022
13 Jan
'22
5:13 p.m.
On 2022/1/13 4:13 下午, Huang, Ying wrote:
zhong jiang <zhongjiang-ali(a)linux.alibaba.com>
writes:
but It will make nr_cpumask_bits equal to NR_CPUS when
CONFIG_CPUMASK_OFFSTACK=n.
The cpu excess nr_cpu_ids should has the some issue.
On 2022/1/13 9:02 H, Huang, Ying wrote:
I think nr_cpumask_bits should be replaced with
num_possible_cpus(), We should can not parse the cpu beyond
max_possible_cpus , is it right ?
If my understanding to the following code were correct, they are same in
most situations,
zhong jiang
<zhongjiang-ali(a)linux.alibaba.com> writes:
> Read tthe patch again, see the following issue.
>
> On 2022/1/12 11:02
H, Huang, Ying wrote:
> Hi,
Jiang,
>
> I failed to reproduce the bug on my side. Could you help me to test
> whether the below patch can fix the bug?
>
> Best Regards,
> Huang, Ying
>
> ------------------------------8<----------------------------------------
> From 919db496945d45e2c593470ce84f5d6c50ae95a8 Mon Sep 17 00:00:00 2001
> From: Huang Ying <ying.huang(a)intel.com>
> Date: Mon, 10 Jan 2022 15:29:38 +0800
> Subject: [PATCH] Fix panic when disabling memory tiering mode dynamically
>
> ---
> include/linux/mm.h | 5 +++++
> kernel/sched/fair.c | 20 +++++++++++++++++---
> 2 files changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index a9ea778eafe0..b22e18676d29 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1440,6 +1440,11 @@ static inline bool __cpupid_match_pid(pid_t task_pid, int
cpupid)
> return (task_pid & LAST__PID_MASK) == cpupid_to_pid(cpupid);
> }
> +static inline bool check_cpupid(int cpupid)
> +{
> + return cpupid_to_cpu(cpupid) >= nr_cpumask_bits;
> +}
> +
Oops. s/>=/</
Oops! Thanks for pointing this out. Have you tested your revised version?
void __init setup_nr_cpu_ids(void)
{
nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
}
And in theory, it's possible that there are "holes" in cpu_possible_mask.
Best Regards,
Huang, Ying
> Thanks,
>
> zhong jiang
>
>> Best Regards,
>> Huang, Ying
>>
>>>> #define cpupid_match_pid(task, cpupid)
__cpupid_match_pid(task->pid, cpupid)
>>>> #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
>>>> static inline int page_cpupid_xchg_last(struct page *page, int
cpupid)
>>>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>>>> index 7ca4ab033180..85a01906d796 100644
>>>> --- a/kernel/sched/fair.c
>>>> +++ b/kernel/sched/fair.c
>>>> @@ -1597,6 +1597,14 @@ bool should_numa_migrate_memory(struct task_struct
*p, struct page * page,
>>>> this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid);
>>>> last_cpupid = page_cpupid_xchg_last(page, this_cpupid);
>>>> + /*
>>>> + * The cpupid may be invalid when NUMA_BALANCING_MEMORY_TIERING
>>>> + * is disabled dynamically.
>>>> + */
>>>> + if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING)
&&
>>>> + !node_is_toptier(src_nid) && !check_cpupid(last_cpupid))
>>>> + return false;
>>>> +
>>>> /*
>>>> * Allow first faults or private faults to migrate immediately early
in
>>>> * the lifetime of a task. The magic number 4 is based on waiting
for
>>>> @@ -2812,9 +2820,15 @@ void task_numa_fault(int last_cpupid, int
mem_node, int pages, int flags)
>>>> if (!p->mm)
>>>> return;
>>>> - /* Numa faults statistics are unnecessary for the slow memory
>>>> node */
>>>> - if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING
&&
>>>> - !node_is_toptier(mem_node))
>>>> + /*
>>>> + * NUMA faults statistics are unnecessary for the slow memory node.
>>>> + *
>>>> + * And, the cpupid may be invalid when NUMA_BALANCING_MEMORY_TIERING
>>>> + * is disabled dynamically.
>>>> + */
>>>> + if (!node_is_toptier(mem_node) &&
>>>> + (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING
||
>>>> + !check_cpupid(last_cpupid)))
>>>> return;
>>>> /* Allocate buffer to track faults on a per-node basis */
>>> _______________________________________________
>>> Pmem mailing list -- pmem(a)lists.openanolis.cn
>>> To unsubscribe send an email to pmem-leave(a)lists.openanolis.cn