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 891FFC433F5 for ; Thu, 17 Feb 2022 10:24:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239191AbiBQKYs (ORCPT ); Thu, 17 Feb 2022 05:24:48 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:60820 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239082AbiBQKY2 (ORCPT ); Thu, 17 Feb 2022 05:24:28 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32317279084; 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=1645093451; 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=jJpK0+bAg4ngggu0bN8b9W4x5mOPd0mVg74Vx0SOVMI=; b=MhPy1Wxj3dfjl57JudEnMiSYyZG94K4eDOJY6lPdnYB+RfsdyWqaCyW/66oVHVGrFSfjNf kNGRe8YazVniA5dAz6mRSyOmggfXUjrTIJdF14iy5V8y+7Mqq65TbisdGGMlfKcybQc2C4 eCjIWZ9f4TpRBsojjym2werZrVVzPZfAfk1ojtP02QD/9l0yAnuQGydXv/fAP4/JY3fwpb hhO0lDml+xuOihRxyO/JF9RyPf0qHiDHl2smgKGRAEi5qCbh79aLwt1prRs4aTaeIvLyJT Z8YMEBghNRvnniEsosjncs/7V2zWr9SL/+1mS2ARNssZLlN5V96vjf8dfdxKyw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1645093451; 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=jJpK0+bAg4ngggu0bN8b9W4x5mOPd0mVg74Vx0SOVMI=; b=fH4WzmOfWB2BxyRt4lgkFSmsETvamjIEdBUkWlNAZoeieRdHgPuWzlxSi3VUa8Byj/YQVr xP8tw4OBhtgWuQDA== 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 4/8] kernel/fork: Don't assign the stack pointer in dup_task_struct(). Date: Thu, 17 Feb 2022 11:24:02 +0100 Message-Id: <20220217102406.3697941-5-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 All four versions of alloc_thread_stack_node() assign now task_struct::stack in case the allocation was successful. Let alloc_thread_stack_node() return an error code instead of the stack pointer and remove the stack assignment in dup_task_struct(). Signed-off-by: Sebastian Andrzej Siewior --- kernel/fork.c | 47 ++++++++++++++++------------------------------- 1 file changed, 16 insertions(+), 31 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index a6697215fe663..546bea2e3b28a 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -211,7 +211,7 @@ static int free_vm_stack_cache(unsigned int cpu) return 0; } =20 -static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int= node) +static int alloc_thread_stack_node(struct task_struct *tsk, int node) { void *stack; int i; @@ -232,7 +232,7 @@ static unsigned long *alloc_thread_stack_node(struct ta= sk_struct *tsk, int node) =20 tsk->stack_vm_area =3D s; tsk->stack =3D s->addr; - return s->addr; + return 0; } =20 /* @@ -245,17 +245,16 @@ static unsigned long *alloc_thread_stack_node(struct = task_struct *tsk, int node) THREADINFO_GFP & ~__GFP_ACCOUNT, PAGE_KERNEL, 0, node, __builtin_return_address(0)); - + if (!stack) + return -ENOMEM; /* * We can't call find_vm_area() in interrupt context, and * free_thread_stack() can be called in interrupt context, * so cache the vm_struct. */ - if (stack) { - tsk->stack_vm_area =3D find_vm_area(stack); - tsk->stack =3D stack; - } - return stack; + tsk->stack_vm_area =3D find_vm_area(stack); + tsk->stack =3D stack; + return 0; } =20 static void free_thread_stack(struct task_struct *tsk) @@ -282,16 +281,16 @@ static void free_thread_stack(struct task_struct *tsk) =20 # else /* !CONFIG_VMAP_STACK */ =20 -static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int= node) +static int alloc_thread_stack_node(struct task_struct *tsk, int node) { struct page *page =3D alloc_pages_node(node, THREADINFO_GFP, THREAD_SIZE_ORDER); =20 if (likely(page)) { tsk->stack =3D kasan_reset_tag(page_address(page)); - return tsk->stack; + return 0; } - return NULL; + return -ENOMEM; } =20 static void free_thread_stack(struct task_struct *tsk) @@ -305,14 +304,13 @@ static void free_thread_stack(struct task_struct *tsk) =20 static struct kmem_cache *thread_stack_cache; =20 -static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, - int node) +static int alloc_thread_stack_node(struct task_struct *tsk, int node) { unsigned long *stack; stack =3D kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node); stack =3D kasan_reset_tag(stack); tsk->stack =3D stack; - return stack; + return stack ? 0 : -ENOMEM; } =20 static void free_thread_stack(struct task_struct *tsk) @@ -332,13 +330,13 @@ void thread_stack_cache_init(void) # endif /* THREAD_SIZE >=3D PAGE_SIZE || defined(CONFIG_VMAP_STACK) */ #else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */ =20 -static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int= node) +static int alloc_thread_stack_node(struct task_struct *tsk, int node) { unsigned long *stack; =20 stack =3D arch_alloc_thread_stack_node(tsk, node); tsk->stack =3D stack; - return stack; + return stack ? 0 : -ENOMEM; } =20 static void free_thread_stack(struct task_struct *tsk) @@ -895,8 +893,6 @@ void set_task_stack_end_magic(struct task_struct *tsk) static struct task_struct *dup_task_struct(struct task_struct *orig, int n= ode) { struct task_struct *tsk; - unsigned long *stack; - struct vm_struct *stack_vm_area __maybe_unused; int err; =20 if (node =3D=3D NUMA_NO_NODE) @@ -909,24 +905,13 @@ static struct task_struct *dup_task_struct(struct tas= k_struct *orig, int node) if (err) goto free_tsk; =20 - stack =3D alloc_thread_stack_node(tsk, node); - if (!stack) + err =3D alloc_thread_stack_node(tsk, node); + if (err) goto free_tsk; =20 if (memcg_charge_kernel_stack(tsk)) goto free_stack; =20 - stack_vm_area =3D task_stack_vm_area(tsk); - - /* - * arch_dup_task_struct() clobbers the stack-related fields. Make - * sure they're properly initialized before using any stack-related - * functions again. - */ - tsk->stack =3D stack; -#ifdef CONFIG_VMAP_STACK - tsk->stack_vm_area =3D stack_vm_area; -#endif #ifdef CONFIG_THREAD_INFO_IN_TASK refcount_set(&tsk->stack_refcount, 1); #endif --=20 2.34.1