On Tue, Aug 14, 2018 at 05:36:19PM -0700, Roman Gushchin wrote:
> @@ -224,9 +224,14 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
> return s->addr;
> }
>
> + /*
> + * Allocated stacks are cached and later reused by new threads,
> + * so memcg accounting is performed manually on assigning/releasing
> + * stacks to tasks. Drop __GFP_ACCOUNT.
> + */
> stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
> VMALLOC_START, VMALLOC_END,
> - THREADINFO_GFP,
> + THREADINFO_GFP & ~__GFP_ACCOUNT,
> PAGE_KERNEL,
> 0, node, __builtin_return_address(0));
>
> @@ -246,12 +251,41 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
> #endif
> }
>
> +static void memcg_charge_kernel_stack(struct task_struct *tsk)
> +{
> +#ifdef CONFIG_VMAP_STACK
> + struct vm_struct *vm = task_stack_vm_area(tsk);
> +
> + if (vm) {
> + int i;
> +
> + for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
> + memcg_kmem_charge(vm->pages[i], __GFP_NOFAIL,
> + compound_order(vm->pages[i]));
> +
> + /* All stack pages belong to the same memcg. */
> + mod_memcg_page_state(vm->pages[0], MEMCG_KERNEL_STACK_KB,
> + THREAD_SIZE / 1024);
> + }
> +#endif
> +}
Before this change, the memory limit can fail the fork, but afterwards
fork() can grow memory consumption unimpeded by the cgroup settings.
Can we continue to use try_charge() here and fail the fork?
