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 X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MSGID_FROM_MTA_HEADER,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8DE46C2BA17 for ; Mon, 6 Apr 2020 16:12:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 42BCE2493E for ; Mon, 6 Apr 2020 16:12:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amdcloud.onmicrosoft.com header.i=@amdcloud.onmicrosoft.com header.b="4L1HuhWX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729498AbgDFQM1 (ORCPT ); Mon, 6 Apr 2020 12:12:27 -0400 Received: from mail-mw2nam12on2076.outbound.protection.outlook.com ([40.107.244.76]:6232 "EHLO NAM12-MW2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728863AbgDFQM0 (ORCPT ); Mon, 6 Apr 2020 12:12:26 -0400 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=AsbScyYYOKaD2n5zMFCUYcF8pWTSDF3N2yv0iVizlTft06lZVQIEcp0BWYzgWFVJ40G9vypreLnPQNJywe9Cxg7HT7lvoYg2r1dKTNcog5S17wmq2bWjvm2QbWNgNllS5yNQ86z6TA1ylpac8ung0gnkrug64Uw4ZWrk4motKFqxsSoSJwROfqiyxPvqjzZ0sgDtzuXjGDl3pKVjQtcr49PdmKzqOY6GK1pt0Q8wTEKOFkroj5dSyKdaKldh/cSCd9ZfQS5sobxMqkY3N+0rjD60F2e5hzIvxM+MiMlaXFlU8BsypuDsDdzguS0JQ1zIIjKAte3uCGZ2ajNCqt7KwA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=/RBY9j/v/uRT01oTDm3Gkx0CuSkvkY86robxKuXud6c=; b=AUV1e8THb5E51tLZlGdQZraXEBnQQhDgLYPAuy/lSR/gXevrfQhTdxGUhEjn/a998IXwkoLY0p0OeWTK6BtyB4WCAqIHWPAPETFsRDAeKJAN9QeGHSc6qEybwqXcr5j+pC79nuV1duH/0Y1Ze1Fxxs93hg1gdUqCffdKaeM0FAzDj4rv2toY0vpMB2rFq3wHjnGI/oIJwhOJSjhiElGiLx9+xwaiyeSPO3wBTlThyRb3GPTWyRsC3vmj/jUzxVHzfyHSB8KsKYJSSS0VGoYcXke6QMaDh/iui9/whZwsbzu/dPMIrEqX5ppGEvAAN8CiQyB4+VRkgAy6mMcIvEZbJQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amdcloud.onmicrosoft.com; s=selector2-amdcloud-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=/RBY9j/v/uRT01oTDm3Gkx0CuSkvkY86robxKuXud6c=; b=4L1HuhWXGg2uRu/p8k3e2cSrUEExagoSFqc+i9eGOHRyIDtIF7LAehSYXP+v5r8qOo0yYdZpdNl6jSRCfqi8qCguQOhoqCy8Rpuf7u3g3gCbhJAwdanSNv8tSHFiJq4zy2xN3R1LXS3KDhvSPJvnHeJgnYZwLB2x1j4cuLZBgs0= Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=Felix.Kuehling@amd.com; Received: from SN1PR12MB2414.namprd12.prod.outlook.com (2603:10b6:802:2e::31) by SN1PR12MB2575.namprd12.prod.outlook.com (2603:10b6:802:25::14) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2878.20; Mon, 6 Apr 2020 16:10:10 +0000 Received: from SN1PR12MB2414.namprd12.prod.outlook.com ([fe80::38ef:1510:9525:f806]) by SN1PR12MB2414.namprd12.prod.outlook.com ([fe80::38ef:1510:9525:f806%7]) with mapi id 15.20.2878.018; Mon, 6 Apr 2020 16:10:10 +0000 Subject: Re: [PATCH 5/6] kernel: better document the use_mm/unuse_mm API contract To: Christoph Hellwig , Linus Torvalds , Andrew Morton Cc: Al Viro , Alex Deucher , Zhenyu Wang , Zhi Wang , Felipe Balbi , "Michael S. Tsirkin" , Jason Wang , Jens Axboe , linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-usb@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, linux-mm@kvack.org References: <20200404094101.672954-1-hch@lst.de> <20200404094101.672954-6-hch@lst.de> From: Felix Kuehling Message-ID: Date: Mon, 6 Apr 2020 12:10:07 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 In-Reply-To: <20200404094101.672954-6-hch@lst.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-ClientProxiedBy: YQBPR0101CA0043.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:c00:1::20) To SN1PR12MB2414.namprd12.prod.outlook.com (2603:10b6:802:2e::31) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [192.168.2.100] (142.116.63.128) by YQBPR0101CA0043.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:c00:1::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2878.15 via Frontend Transport; Mon, 6 Apr 2020 16:10:09 +0000 X-Originating-IP: [142.116.63.128] X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: 0a314b22-a5c7-4620-1090-08d7da44fb44 X-MS-TrafficTypeDiagnostic: SN1PR12MB2575:|SN1PR12MB2575: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:9508; X-Forefront-PRVS: 0365C0E14B X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SN1PR12MB2414.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFTY:;SFS:(10009020)(4636009)(396003)(346002)(136003)(366004)(39860400002)(376002)(16576012)(54906003)(110136005)(86362001)(31696002)(4326008)(8676002)(52116002)(81156014)(81166006)(8936002)(6486002)(44832011)(2616005)(66476007)(316002)(478600001)(956004)(2906002)(36756003)(66556008)(31686004)(5660300002)(7416002)(186003)(16526019)(26005)(66946007);DIR:OUT;SFP:1101; Received-SPF: None (protection.outlook.com: amd.com does not designate permitted sender hosts) X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 7A3Xk55dvXk6c3URnUVKRYpohIGCp0OagUNKu5mAAZJ34MyO19jO0BML1o80C9mvwlOkEFNdGkGtfJES8TeMu57nMhK7NrbR19YSRdUyMxuHhqNsqkp8o46nnndiCu4JMC4GWsBTqKdwkYS0cAi7rTby/Q/GMKRtIHIwXf+9J97Wdowm19X6TLP438IUkELJ3BxxSDnjGcako2GEMH8F0XZNIbwbdxwPCw9EP8AJFWWNSTNdGZGmPQsZQUyCSPcQf4okmf55xHtLsMIr20pD6PcepsqvkLW1pc5kw8L+PYVkOb8h9x1+2aFmBKPQo8GqiLQZ42GJX2L9prUALwxUkJEFI2WCU+qFd/vvaTloYSpl6klQQO0fGaCPBwI2fhLvPQOEJTTv6QdKLlwt74Bmd33PedWduY7bt1q12I5QC6h6JIXE+F/dzrOhhOHvHX7q X-MS-Exchange-AntiSpam-MessageData: Cc7MgPE7Z5uEkT4A2b1lOiKwvNaT5cGj7WdDRxBpn6wTpJDjenHUqrbMgIXgpBWEQKL8KCw6npiDK1pNDsZTfCQnZkD+ikZW6/3/NalfK1W1CVw993bpHVCk73l5ssNcL+jiWQIKz17a2OAG1DM6zw== X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0a314b22-a5c7-4620-1090-08d7da44fb44 X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Apr 2020 16:10:10.7525 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: nKCEnEVK5PYqq+ucQcG6vBu7LdwSq/5HCWQxZ450xbW6Uc9qZzH7nQl4EWDZjrcg1hdzbxBn7hwKf3jicEICjQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN1PR12MB2575 Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Am 2020-04-04 um 5:41 a.m. schrieb Christoph Hellwig: > Switch the function documentation to kerneldoc comments, and add > WARN_ON_ONCE asserts that the calling thread is a kernel thread and > does not have ->mm set (or has ->mm set in the case of unuse_mm). > > Also give the functions a kthread_ prefix to better document the > use case. > > Signed-off-by: Christoph Hellwig Acked-by: Felix Kuehling > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h | 4 +-- > drivers/gpu/drm/i915/gvt/kvmgt.c | 4 +-- > drivers/usb/gadget/function/f_fs.c | 4 +-- > drivers/usb/gadget/legacy/inode.c | 4 +-- > drivers/vhost/vhost.c | 4 +-- > fs/io-wq.c | 6 ++-- > fs/io_uring.c | 6 ++-- > include/linux/kthread.h | 4 +-- > kernel/kthread.c | 33 +++++++++++----------- > mm/oom_kill.c | 6 ++-- > mm/vmacache.c | 4 +-- > 11 files changed, 39 insertions(+), 40 deletions(-) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h > index bce5e93fefc8..63db84e09408 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h > @@ -192,9 +192,9 @@ uint8_t amdgpu_amdkfd_get_xgmi_hops_count(struct kgd_dev *dst, struct kgd_dev *s > if ((mmptr) == current->mm) { \ > valid = !get_user((dst), (wptr)); \ > } else if (current->flags & PF_KTHREAD) { \ > - use_mm(mmptr); \ > + kthread_use_mm(mmptr); \ > valid = !get_user((dst), (wptr)); \ > - unuse_mm(mmptr); \ > + kthread_unuse_mm(mmptr); \ > } \ > pagefault_enable(); \ > } \ > diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c > index dee01c371bf5..92e9b340dbc2 100644 > --- a/drivers/gpu/drm/i915/gvt/kvmgt.c > +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c > @@ -2048,7 +2048,7 @@ static int kvmgt_rw_gpa(unsigned long handle, unsigned long gpa, > if (kthread) { > if (!mmget_not_zero(kvm->mm)) > return -EFAULT; > - use_mm(kvm->mm); > + kthread_use_mm(kvm->mm); > } > > idx = srcu_read_lock(&kvm->srcu); > @@ -2057,7 +2057,7 @@ static int kvmgt_rw_gpa(unsigned long handle, unsigned long gpa, > srcu_read_unlock(&kvm->srcu, idx); > > if (kthread) { > - unuse_mm(kvm->mm); > + kthread_unuse_mm(kvm->mm); > mmput(kvm->mm); > } > > diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c > index c57b1b2507c6..d9e48bd7c692 100644 > --- a/drivers/usb/gadget/function/f_fs.c > +++ b/drivers/usb/gadget/function/f_fs.c > @@ -827,9 +827,9 @@ static void ffs_user_copy_worker(struct work_struct *work) > mm_segment_t oldfs = get_fs(); > > set_fs(USER_DS); > - use_mm(io_data->mm); > + kthread_use_mm(io_data->mm); > ret = ffs_copy_to_iter(io_data->buf, ret, &io_data->data); > - unuse_mm(io_data->mm); > + kthread_unuse_mm(io_data->mm); > set_fs(oldfs); > } > > diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c > index 8b5233888bf8..a05552bc2ff8 100644 > --- a/drivers/usb/gadget/legacy/inode.c > +++ b/drivers/usb/gadget/legacy/inode.c > @@ -462,9 +462,9 @@ static void ep_user_copy_worker(struct work_struct *work) > struct kiocb *iocb = priv->iocb; > size_t ret; > > - use_mm(mm); > + kthread_use_mm(mm); > ret = copy_to_iter(priv->buf, priv->actual, &priv->to); > - unuse_mm(mm); > + kthread_unuse_mm(mm); > if (!ret) > ret = -EFAULT; > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index 4e9ce54869af..1787d426a956 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -336,7 +336,7 @@ static int vhost_worker(void *data) > mm_segment_t oldfs = get_fs(); > > set_fs(USER_DS); > - use_mm(dev->mm); > + kthread_use_mm(dev->mm); > > for (;;) { > /* mb paired w/ kthread_stop */ > @@ -364,7 +364,7 @@ static int vhost_worker(void *data) > schedule(); > } > } > - unuse_mm(dev->mm); > + kthread_unuse_mm(dev->mm); > set_fs(oldfs); > return 0; > } > diff --git a/fs/io-wq.c b/fs/io-wq.c > index c49c2bdbafb5..83c2868eff2a 100644 > --- a/fs/io-wq.c > +++ b/fs/io-wq.c > @@ -169,7 +169,7 @@ static bool __io_worker_unuse(struct io_wqe *wqe, struct io_worker *worker) > } > __set_current_state(TASK_RUNNING); > set_fs(KERNEL_DS); > - unuse_mm(worker->mm); > + kthread_unuse_mm(worker->mm); > mmput(worker->mm); > worker->mm = NULL; > } > @@ -416,7 +416,7 @@ static struct io_wq_work *io_get_next_work(struct io_wqe *wqe) > static void io_wq_switch_mm(struct io_worker *worker, struct io_wq_work *work) > { > if (worker->mm) { > - unuse_mm(worker->mm); > + kthread_unuse_mm(worker->mm); > mmput(worker->mm); > worker->mm = NULL; > } > @@ -425,7 +425,7 @@ static void io_wq_switch_mm(struct io_worker *worker, struct io_wq_work *work) > return; > } > if (mmget_not_zero(work->mm)) { > - use_mm(work->mm); > + kthread_use_mm(work->mm); > if (!worker->mm) > set_fs(USER_DS); > worker->mm = work->mm; > diff --git a/fs/io_uring.c b/fs/io_uring.c > index 27a4ecb724ca..367406381044 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -5839,7 +5839,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr, > err = -EFAULT; > goto fail_req; > } > - use_mm(ctx->sqo_mm); > + kthread_use_mm(ctx->sqo_mm); > *mm = ctx->sqo_mm; > } > > @@ -5911,7 +5911,7 @@ static int io_sq_thread(void *data) > * may sleep. > */ > if (cur_mm) { > - unuse_mm(cur_mm); > + kthread_unuse_mm(cur_mm); > mmput(cur_mm); > cur_mm = NULL; > } > @@ -5987,7 +5987,7 @@ static int io_sq_thread(void *data) > > set_fs(old_fs); > if (cur_mm) { > - unuse_mm(cur_mm); > + kthread_unuse_mm(cur_mm); > mmput(cur_mm); > } > revert_creds(old_cred); > diff --git a/include/linux/kthread.h b/include/linux/kthread.h > index c2d40c9672d6..12258ea077cf 100644 > --- a/include/linux/kthread.h > +++ b/include/linux/kthread.h > @@ -200,8 +200,8 @@ bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *work); > > void kthread_destroy_worker(struct kthread_worker *worker); > > -void use_mm(struct mm_struct *mm); > -void unuse_mm(struct mm_struct *mm); > +void kthread_use_mm(struct mm_struct *mm); > +void kthread_unuse_mm(struct mm_struct *mm); > > struct cgroup_subsys_state; > > diff --git a/kernel/kthread.c b/kernel/kthread.c > index ce4610316377..316db17f6b4f 100644 > --- a/kernel/kthread.c > +++ b/kernel/kthread.c > @@ -1208,18 +1208,18 @@ void kthread_destroy_worker(struct kthread_worker *worker) > } > EXPORT_SYMBOL(kthread_destroy_worker); > > -/* > - * use_mm > - * Makes the calling kernel thread take on the specified > - * mm context. > - * (Note: this routine is intended to be called only > - * from a kernel thread context) > +/** > + * kthread_use_mm - make the calling kthread operate on an address space > + * @mm: address space to operate on > */ > -void use_mm(struct mm_struct *mm) > +void kthread_use_mm(struct mm_struct *mm) > { > struct mm_struct *active_mm; > struct task_struct *tsk = current; > > + WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); > + WARN_ON_ONCE(tsk->mm); > + > task_lock(tsk); > active_mm = tsk->active_mm; > if (active_mm != mm) { > @@ -1236,20 +1236,19 @@ void use_mm(struct mm_struct *mm) > if (active_mm != mm) > mmdrop(active_mm); > } > -EXPORT_SYMBOL_GPL(use_mm); > +EXPORT_SYMBOL_GPL(kthread_use_mm); > > -/* > - * unuse_mm > - * Reverses the effect of use_mm, i.e. releases the > - * specified mm context which was earlier taken on > - * by the calling kernel thread > - * (Note: this routine is intended to be called only > - * from a kernel thread context) > +/** > + * kthread_use_mm - reverse the effect of kthread_use_mm() > + * @mm: address space to operate on > */ > -void unuse_mm(struct mm_struct *mm) > +void kthread_unuse_mm(struct mm_struct *mm) > { > struct task_struct *tsk = current; > > + WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); > + WARN_ON_ONCE(!tsk->mm); > + > task_lock(tsk); > sync_mm_rss(mm); > tsk->mm = NULL; > @@ -1257,7 +1256,7 @@ void unuse_mm(struct mm_struct *mm) > enter_lazy_tlb(mm, tsk); > task_unlock(tsk); > } > -EXPORT_SYMBOL_GPL(unuse_mm); > +EXPORT_SYMBOL_GPL(kthread_unuse_mm); > > #ifdef CONFIG_BLK_CGROUP > /** > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index dfc357614e56..958d2972313f 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -126,7 +126,7 @@ static bool oom_cpuset_eligible(struct task_struct *tsk, struct oom_control *oc) > > /* > * The process p may have detached its own ->mm while exiting or through > - * use_mm(), but one or more of its subthreads may still have a valid > + * kthread_use_mm(), but one or more of its subthreads may still have a valid > * pointer. Return p, or any of its subthreads with a valid ->mm, with > * task_lock() held. > */ > @@ -919,8 +919,8 @@ static void __oom_kill_process(struct task_struct *victim, const char *message) > continue; > } > /* > - * No use_mm() user needs to read from the userspace so we are > - * ok to reap it. > + * No kthead_use_mm() user needs to read from the userspace so > + * we are ok to reap it. > */ > if (unlikely(p->flags & PF_KTHREAD)) > continue; > diff --git a/mm/vmacache.c b/mm/vmacache.c > index cdc32a3b02fa..ceedbab82106 100644 > --- a/mm/vmacache.c > +++ b/mm/vmacache.c > @@ -25,8 +25,8 @@ > * task's vmacache pertains to a different mm (ie, its own). There is > * nothing we can do here. > * > - * Also handle the case where a kernel thread has adopted this mm via use_mm(). > - * That kernel thread's vmacache is not applicable to this mm. > + * Also handle the case where a kernel thread has adopted this mm via > + * kthread_use_mm(). That kernel thread's vmacache is not applicable to this mm. > */ > static inline bool vmacache_valid_mm(struct mm_struct *mm) > {