Messages in this thread | | | From | Hoeun Ryu <> | Date | Fri, 10 Feb 2017 23:31:41 +0900 | Subject | Re: [PATCH v3] fork: free vmapped stacks in cache when cpus are offline |
| |
On Fri, Feb 10, 2017 at 9:05 PM, Michal Hocko <mhocko@kernel.org> wrote: > On Fri 10-02-17 17:32:07, Hoeun Ryu wrote: > [...] >> +static int free_vm_stack_cache(unsigned int cpu) >> +{ >> + struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu); >> + int i; >> + >> + for (i = 0; i < NR_CACHED_STACKS; i++) { >> + struct vm_struct **vm_stack = &cached_vm_stacks[i]; >> + >> + if (*vm_stack == NULL) >> + continue; >> + >> + vfree((*vm_stack)->addr); >> + *vm_stack = NULL; > > this seems more obscure than necessary. Probably a matter of taste but I > would find the following easier to read > struct vm_struct *vm_stack = cached_vm_stacks[i]; > > if (!vm_stack) > continue; > > vfree(vm_stack); > cached_vm_stacks[i] = NULL; >
OK, it's easier to read, I'll fix it.
>> + } >> + >> + return 0; >> +} >> #endif >> >> static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node) >> @@ -456,6 +474,11 @@ void __init fork_init(void) >> for (i = 0; i < UCOUNT_COUNTS; i++) { >> init_user_ns.ucount_max[i] = max_threads/2; >> } >> + >> +#ifdef CONFIG_VMAP_STACK >> + cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "vm_stack_cache", >> + NULL, free_vm_stack_cache); >> +#endif > > I am not familiar the new hotplug infrastructure so I might be missing > something. CPUHP_AP_ONLINE_DYN will allocate a state which is has only > 30 slots available. The name also suggests this will be called on an > online event. Why doesn't this have its own state like other users. The > name should also reflect offline event CPUHP_STACK_CACHE_DEAD or > something like that.
I'll define CPUHP_VMSTACK_CACHE_DEAD before CPUHP_BP_PREPARE_DYN in cpuhotplug.h. Do you think the change is made in a separate patch or not ?
Thank you for your review anyway.
> > -- > Michal Hocko > SUSE Labs
| |