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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Dh4+9ecv; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7EC616098F7B; Wed, 4 Nov 2026 19:31:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Dh4+9ecv Received: by smtp.kernel.org (Postfix) with ESMTPSA id 687711F000C1; Wed, 4 Nov 2026 19:31:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793820687; bh=bjqF3ZSgIkS8AxB/0gXg0jui/+Bk+KSQrJMcvTLEX2w=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Dh4+9ecvQB/fdnQu6iIgUdLitJTdUwSJc5BAzDIq1qPmyyBsLXMabQ9foglBU5ZZk D6dhOELZP9dQIpo8eFmCT1yoTqui+Hn74TN2TQ9m6gfhaLGyqgAv5ntXFWKN8wAHhQ /6byjaao1BwOH4Xai+HEyQOI6e/gWLDq98aIixonysCh6etvtlDKMj3AuVvPVu3tsw 5yvXgeRWG97WSiJ8+rXzjm1pZlYM0bmc4ErrGRCLUJOuwj2//3rOKEvklQFEtd6dMr Xkhr+NYlwLfljsfMngXmQfIsaH5htjwyjQ0VvTX4mjMAxmPzkh6surCpnkirsI8ZKl 6ZVK+A7zumtvw== From: Christian Brauner To: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds , Jann Horn , Josef Bacik , Chris Mason , Jeff Layton , NeilBrown , Eric Dumazet , Thomas Gleixner , Al Viro , Jonathan Corbet , Christoph Hellwig , Greg Kroah-Hartman , Joel Granados , Kees Cook , Jan Kara , Jan Kara , linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, linux-um@lists.infradead.org, linux-wireless@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, ntfs3@lists.linux.dev, platform-driver-x86@vger.kernel.org, coreteam@netfilter.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, linux-sound@vger.kernel.org, netfilter-devel@vger.kernel.org, dri-devel@lists.freedesktop.org, ibm-acpi-devel@lists.sourceforge.net, jfs-discussion@lists.sourceforge.net, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-cifs@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-mm@kvack.org, linux-sh@vger.kernel.org, linux-usb@vger.kernel.org, samba-technical@lists.samba.org, sparclinux@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-doc@vger.kernel.org, linux-serial@vger.kernel.org, linux-atm-general@lists.sourceforge.net, Takashi Iwai , linux-input@vger.kernel.org, linux-raid@vger.kernel.org, linux-ext4@vger.kernel.org, linux-modules@vger.kernel.org, linux-debuggers@vger.kernel.org, "Christian Brauner (Amutable)" , Chuck Lever Subject: [PATCH RESEND v2 08/23] proc: let procfs own the seq_file of proc_create_seq() and friends Date: Wed, 4 Nov 2026 20:31:13 +0100 Message-ID: <20261104-work-procfs-core-v2-8-76ace653a773@kernel.org> In-Reply-To: <20261104-work-procfs-core-v2-0-76ace653a773@kernel.org> References: <20261104-work-procfs-core-v2-0-76ace653a773@kernel.org> X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" X-Mailer: b4 0.17-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=7182; i=brauner@kernel.org; h=from:subject:message-id; bh=d/Gyh84EIwCT+5DcGz0I5uORN2AuffY7nyAO9oBimYM=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWS9bq/aal96f3tFqaCN0pN9q9rO5ck4bXgt+OJkDedjT k3Ly9cOdpSyMIhxMciKKbI4tJuEyy3nqdhslKkBM4eVCWQIAxenAEyEoZThD8+k4hrP6re7Hkgc jbw6N1dbZKrL1NVf5v3WTGtP3x1x+CvDH27eBy/1WC0LY1+Kxcy9e6R3dl2B6kXN8Ih/XprfWp2 ruQA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Content-Transfer-Encoding: 8bit proc_create_seq_private(), proc_create_single_data() and their network namespace variants keep the seq_operations or the show function in the entry already. Let procfs own the seq_file for all of them. For the network namespace variants ->proc_open() and ->proc_release() keep taking and dropping the reference to the network namespace. That's most of /proc/net, among them the files of xt_hashlimit and /proc/net/dev_snmp6/. A reader that faults on its buffer no longer holds up their removal. Reported-by: Chris Mason Fixes: 786d7e1612f0 ("Fix rmmod/read/write races in /proc entries") Signed-off-by: Christian Brauner (Amutable) --- fs/proc/generic.c | 42 ++++-------------------------------------- fs/proc/proc_net.c | 40 +++++++++++++--------------------------- 2 files changed, 17 insertions(+), 65 deletions(-) diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 59b89e251ba3..959bf9e33245 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -737,30 +737,9 @@ struct proc_dir_entry *proc_create(const char *name, umode_t mode, } EXPORT_SYMBOL(proc_create); -static int proc_seq_open(struct inode *inode, struct file *file) -{ - struct proc_dir_entry *de = PDE(inode); - - if (de->state_size) - return seq_open_private(file, de->seq_ops, de->state_size); - return seq_open(file, de->seq_ops); -} - -static int proc_seq_release(struct inode *inode, struct file *file) -{ - struct proc_dir_entry *de = PDE(inode); - - if (de->state_size) - return seq_release_private(inode, file); - return seq_release(inode, file); -} - +/* procfs owns the seq_file of these, see pde_seq_start() */ static const struct proc_ops proc_seq_ops = { /* not permanent -- can call into arbitrary seq_operations */ - .proc_open = proc_seq_open, - .proc_read_iter = seq_read_iter, - .proc_lseek = seq_lseek, - .proc_release = proc_seq_release, }; struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode, @@ -775,25 +754,11 @@ struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode, p->proc_ops = &proc_seq_ops; p->seq_ops = ops; p->state_size = state_size; + p->flags |= PROC_ENTRY_proc_seq_ops; return proc_register(parent, p); } EXPORT_SYMBOL(proc_create_seq_private); -static int proc_single_open(struct inode *inode, struct file *file) -{ - struct proc_dir_entry *de = PDE(inode); - - return single_open(file, de->single_show, de->data); -} - -static const struct proc_ops proc_single_ops = { - /* not permanent -- can call into arbitrary ->single_show */ - .proc_open = proc_single_open, - .proc_read_iter = seq_read_iter, - .proc_lseek = seq_lseek, - .proc_release = single_release, -}; - struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode, struct proc_dir_entry *parent, int (*show)(struct seq_file *, void *), void *data) @@ -803,8 +768,9 @@ struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode, p = proc_create_reg(name, mode, &parent, data); if (!p) return NULL; - p->proc_ops = &proc_single_ops; + p->proc_ops = &proc_seq_ops; p->single_show = show; + p->flags |= PROC_ENTRY_proc_show; return proc_register(parent, p); } EXPORT_SYMBOL(proc_create_single_data); diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index df5484813d5d..9973f846c467 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -37,13 +37,13 @@ static struct net *get_proc_net(const struct inode *inode) return maybe_get_net(PDE_NET(PDE(inode))); } +/* procfs opened the seq_file and allocated its state, see pde_seq_start() */ static int seq_open_net(struct inode *inode, struct file *file) { - unsigned int state_size = PDE(inode)->state_size; - struct seq_net_private *p; + struct seq_net_private *p = ((struct seq_file *)file->private_data)->private; struct net *net; - WARN_ON_ONCE(state_size < sizeof(*p)); + WARN_ON_ONCE(PDE(inode)->state_size < sizeof(*p)); if (file->f_mode & FMODE_WRITE && !PDE(inode)->write) return -EACCES; @@ -51,12 +51,6 @@ static int seq_open_net(struct inode *inode, struct file *file) net = get_proc_net(inode); if (!net) return -ENXIO; - - p = __seq_open_private(file, PDE(inode)->seq_ops, state_size); - if (!p) { - put_net(net); - return -ENOMEM; - } #ifdef CONFIG_NET_NS p->net = net; netns_tracker_alloc(net, &p->ns_tracker, GFP_KERNEL); @@ -77,18 +71,13 @@ static void seq_file_net_put_net(struct seq_file *seq) static int seq_release_net(struct inode *ino, struct file *f) { - struct seq_file *seq = f->private_data; - - seq_file_net_put_net(seq); - seq_release_private(ino, f); + seq_file_net_put_net(f->private_data); return 0; } static const struct proc_ops proc_net_seq_ops = { .proc_open = seq_open_net, - .proc_read = seq_read, .proc_write = proc_simple_write, - .proc_lseek = seq_lseek, .proc_release = seq_release_net, }; @@ -125,6 +114,7 @@ struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode, p->proc_ops = &proc_net_seq_ops; p->seq_ops = ops; p->state_size = state_size; + p->flags |= PROC_ENTRY_proc_seq_ops; return proc_register(parent, p); } EXPORT_SYMBOL_GPL(proc_create_net_data); @@ -170,6 +160,7 @@ struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode p->proc_ops = &proc_net_seq_ops; p->seq_ops = ops; p->state_size = state_size; + p->flags |= PROC_ENTRY_proc_seq_ops; p->write = write; return proc_register(parent, p); } @@ -177,32 +168,25 @@ EXPORT_SYMBOL_GPL(proc_create_net_data_write); static int single_open_net(struct inode *inode, struct file *file) { - struct proc_dir_entry *de = PDE(inode); - struct net *net; - int err; + struct net *net = get_proc_net(inode); - net = get_proc_net(inode); if (!net) return -ENXIO; - - err = single_open(file, de->single_show, net); - if (err) - put_net(net); - return err; + ((struct seq_file *)file->private_data)->private = net; + return 0; } static int single_release_net(struct inode *ino, struct file *f) { struct seq_file *seq = f->private_data; + put_net(seq->private); - return single_release(ino, f); + return 0; } static const struct proc_ops proc_net_single_ops = { .proc_open = single_open_net, - .proc_read = seq_read, .proc_write = proc_simple_write, - .proc_lseek = seq_lseek, .proc_release = single_release_net, }; @@ -218,6 +202,7 @@ struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode, pde_force_lookup(p); p->proc_ops = &proc_net_single_ops; p->single_show = show; + p->flags |= PROC_ENTRY_proc_show; return proc_register(parent, p); } EXPORT_SYMBOL_GPL(proc_create_net_single); @@ -261,6 +246,7 @@ struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mo pde_force_lookup(p); p->proc_ops = &proc_net_single_ops; p->single_show = show; + p->flags |= PROC_ENTRY_proc_show; p->write = write; return proc_register(parent, p); } -- 2.53.0