From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3A56BC433F5 for ; Thu, 17 Feb 2022 10:24:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239250AbiBQKY5 (ORCPT ); Thu, 17 Feb 2022 05:24:57 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:60834 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239119AbiBQKY2 (ORCPT ); Thu, 17 Feb 2022 05:24:28 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E63E827908B; Thu, 17 Feb 2022 02:24:13 -0800 (PST) From: Sebastian Andrzej Siewior DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1645093452; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tzmkYQx1xEwd8qVOArg0icKqGEVrOwoPune071DIWs8=; b=d1irsmpnpAwkcPjHdfgmtqMiHqSi+YL/levDedGRPQEn1oS4VFnwx6l9/ejdwGj+bvhf2p +xXVb6+/r2EpVUpUeLcq6xBptRmty36qUk1VE7luZ9DmWWhZSFnw1a4ciRXv8Y8M5XiOCq brO5btU1XSHG3VEAQI+Ypzwy22Notd8+Gpt5VbsjrjNZ2iUgci1VLa6B6XQ9uxkC6V288Y Lps/wh2zvZcVVA/A2Nga6Aw2Dq65cTqEwjbYdcAXwHZYlu5SM/CCjyFgIad5HWaFExUnFB bvpY8oiKOCirUZX6x+zgXcs2lznrruZacG0EHw23kgiHI1KQZVoz3l4koqWKhA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1645093452; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tzmkYQx1xEwd8qVOArg0icKqGEVrOwoPune071DIWs8=; b=Lk1Szs2FYGOr7TkfHTqLlL31Z65/3LhH7VGR35I5JpgSTBGvZiWkTz2GmzxDot2rwu3DX7 ZKT1iiITznfAPgBA== To: linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org Cc: Andy Lutomirski , Ben Segall , Daniel Bristot de Oliveira , Dietmar Eggemann , Ingo Molnar , Juri Lelli , Peter Zijlstra , Steven Rostedt , Thomas Gleixner , Vincent Guittot , Sebastian Andrzej Siewior Subject: [PATCH v2 6/8] kernel/fork: Move task stack account to do_exit(). Date: Thu, 17 Feb 2022 11:24:04 +0100 Message-Id: <20220217102406.3697941-7-bigeasy@linutronix.de> In-Reply-To: <20220217102406.3697941-1-bigeasy@linutronix.de> References: <20220217102406.3697941-1-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is no need to perform the stack accounting of the outgoing task in its final schedule() invocation which happens with disabled preemption. The task is leaving, the resources will be freed and the accounting can happen in do_exit() before the actual schedule invocation which frees the stack memory. Move the accounting of the stack memory from release_task_stack() to exit_task_stack_account() which then can be invoked from do_exit(). Signed-off-by: Sebastian Andrzej Siewior --- include/linux/sched/task_stack.h | 2 ++ kernel/exit.c | 1 + kernel/fork.c | 35 +++++++++++++++++++++----------- 3 files changed, 26 insertions(+), 12 deletions(-) diff --git a/include/linux/sched/task_stack.h b/include/linux/sched/task_st= ack.h index d10150587d819..892562ebbd3aa 100644 --- a/include/linux/sched/task_stack.h +++ b/include/linux/sched/task_stack.h @@ -79,6 +79,8 @@ static inline void *try_get_task_stack(struct task_struct= *tsk) static inline void put_task_stack(struct task_struct *tsk) {} #endif =20 +void exit_task_stack_account(struct task_struct *tsk); + #define task_stack_end_corrupted(task) \ (*(end_of_stack(task)) !=3D STACK_END_MAGIC) =20 diff --git a/kernel/exit.c b/kernel/exit.c index b00a25bb4ab93..c303cffe7fdb4 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -845,6 +845,7 @@ void __noreturn do_exit(long code) put_page(tsk->task_frag.page); =20 validate_creds_for_do_exit(tsk); + exit_task_stack_account(tsk); =20 check_stack_usage(); preempt_disable(); diff --git a/kernel/fork.c b/kernel/fork.c index 919bdcf21b8e5..984f69d6f211f 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -211,9 +211,8 @@ static int free_vm_stack_cache(unsigned int cpu) return 0; } =20 -static int memcg_charge_kernel_stack(struct task_struct *tsk) +static int memcg_charge_kernel_stack(struct vm_struct *vm) { - struct vm_struct *vm =3D task_stack_vm_area(tsk); int i; int ret; =20 @@ -239,6 +238,7 @@ static int memcg_charge_kernel_stack(struct task_struct= *tsk) =20 static int alloc_thread_stack_node(struct task_struct *tsk, int node) { + struct vm_struct *vm; void *stack; int i; =20 @@ -256,7 +256,7 @@ static int alloc_thread_stack_node(struct task_struct *= tsk, int node) /* Clear stale pointers from reused stack. */ memset(s->addr, 0, THREAD_SIZE); =20 - if (memcg_charge_kernel_stack(tsk)) { + if (memcg_charge_kernel_stack(s)) { vfree(s->addr); return -ENOMEM; } @@ -279,7 +279,8 @@ static int alloc_thread_stack_node(struct task_struct *= tsk, int node) if (!stack) return -ENOMEM; =20 - if (memcg_charge_kernel_stack(tsk)) { + vm =3D find_vm_area(stack); + if (memcg_charge_kernel_stack(vm)) { vfree(stack); return -ENOMEM; } @@ -288,19 +289,15 @@ static int alloc_thread_stack_node(struct task_struct= *tsk, int node) * free_thread_stack() can be called in interrupt context, * so cache the vm_struct. */ - tsk->stack_vm_area =3D find_vm_area(stack); + tsk->stack_vm_area =3D vm; tsk->stack =3D stack; return 0; } =20 static void free_thread_stack(struct task_struct *tsk) { - struct vm_struct *vm =3D task_stack_vm_area(tsk); int i; =20 - for (i =3D 0; i < THREAD_SIZE / PAGE_SIZE; i++) - memcg_kmem_uncharge_page(vm->pages[i], 0); - for (i =3D 0; i < NR_CACHED_STACKS; i++) { if (this_cpu_cmpxchg(cached_stacks[i], NULL, tsk->stack_vm_area) !=3D NULL) @@ -454,12 +451,25 @@ static void account_kernel_stack(struct task_struct *= tsk, int account) } } =20 +void exit_task_stack_account(struct task_struct *tsk) +{ + account_kernel_stack(tsk, -1); + + if (IS_ENABLED(CONFIG_VMAP_STACK)) { + struct vm_struct *vm; + int i; + + vm =3D task_stack_vm_area(tsk); + for (i =3D 0; i < THREAD_SIZE / PAGE_SIZE; i++) + memcg_kmem_uncharge_page(vm->pages[i], 0); + } +} + static void release_task_stack(struct task_struct *tsk) { if (WARN_ON(READ_ONCE(tsk->__state) !=3D TASK_DEAD)) return; /* Better to leak the stack than to free prematurely */ =20 - account_kernel_stack(tsk, -1); free_thread_stack(tsk); } =20 @@ -918,6 +928,7 @@ static struct task_struct *dup_task_struct(struct task_= struct *orig, int node) #ifdef CONFIG_THREAD_INFO_IN_TASK refcount_set(&tsk->stack_refcount, 1); #endif + account_kernel_stack(tsk, 1); =20 err =3D scs_prepare(tsk, node); if (err) @@ -961,8 +972,6 @@ static struct task_struct *dup_task_struct(struct task_= struct *orig, int node) tsk->wake_q.next =3D NULL; tsk->worker_private =3D NULL; =20 - account_kernel_stack(tsk, 1); - kcov_task_init(tsk); kmap_local_fork(tsk); =20 @@ -981,6 +990,7 @@ static struct task_struct *dup_task_struct(struct task_= struct *orig, int node) return tsk; =20 free_stack: + exit_task_stack_account(tsk); free_thread_stack(tsk); free_tsk: free_task_struct(tsk); @@ -2449,6 +2459,7 @@ static __latent_entropy struct task_struct *copy_proc= ess( exit_creds(p); bad_fork_free: WRITE_ONCE(p->__state, TASK_DEAD); + exit_task_stack_account(p); put_task_stack(p); delayed_free_task(p); fork_out: --=20 2.34.1