From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753214Ab3KYWNa (ORCPT ); Mon, 25 Nov 2013 17:13:30 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:56843 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751986Ab3KYWN3 (ORCPT ); Mon, 25 Nov 2013 17:13:29 -0500 Date: Mon, 25 Nov 2013 14:13:28 -0800 From: Andrew Morton To: "Jan Beulich" Cc: , , , Subject: Re: [PATCH] procfs: also fix proc_reg_get_unmapped_area() for !MMU case Message-Id: <20131125141328.d9da16e10526e2ff1d368f0f@linux-foundation.org> In-Reply-To: <529387570200007800106C9F@nat28.tlf.novell.com> References: <529387570200007800106C9F@nat28.tlf.novell.com> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 25 Nov 2013 16:22:31 +0000 "Jan Beulich" wrote: > Commit fad1a86e ("procfs: call default get_unmapped_area on MMU-present > architectures"), as its title says, took care of only the MMU case, > leaving the !MMU side still in the regressed state (returning -EIO in > all cases where pde->proc_fops->get_unmapped_area is NULL). The changelog is rather mystifying unless the reader goes off and finds the fad1a86e changelog, so let's do that for them by adding this: >>From the fad1a86e changelog: : Commit c4fe24485729 ("sparc: fix PCI device proc file mmap(2)") added : proc_reg_get_unmapped_area in proc_reg_file_ops and : proc_reg_file_ops_no_compat, by which now mmap always returns EIO if : get_unmapped_area method is not defined for the target procfs file, which : causes regression of mmap on /proc/vmcore. : : To address this issue, like get_unmapped_area(), call default : current->mm->get_unmapped_area on MMU-present architectures if : pde->proc_fops->get_unmapped_area, i.e. the one in actual file operation : in the procfs file, is not defined. > Signed-off-by: Jan Beulich > Cc: HATAYAMA Daisuke > Cc: Alexey Dobriyan > Cc: David S. Miller I tagged this with Cc: [3.12.x] OK? > +++ 3.13-rc1-proc-get-unmapped-area/fs/proc/inode.c > @@ -292,16 +292,19 @@ proc_reg_get_unmapped_area(struct file * > { > struct proc_dir_entry *pde = PDE(file_inode(file)); > unsigned long rv = -EIO; > - unsigned long (*get_area)(struct file *, unsigned long, unsigned long, > - unsigned long, unsigned long) = NULL; > + > if (use_pde(pde)) { > + typeof(proc_reg_get_unmapped_area) *get_area > #ifdef CONFIG_MMU > - get_area = current->mm->get_unmapped_area; > + = pde->proc_fops->get_unmapped_area > + ?: current->mm->get_unmapped_area; > +#else > + = pde->proc_fops->get_unmapped_area; > #endif > - if (pde->proc_fops->get_unmapped_area) > - get_area = pde->proc_fops->get_unmapped_area; > - if (get_area) > - rv = get_area(file, orig_addr, len, pgoff, flags); > + > + rv = get_area > + ? get_area(file, orig_addr, len, pgoff, flags) > + : orig_addr; > unuse_pde(pde); > } > return rv; That function has gone from bad to worse :( How does this version look? It would be acceptable and beneficial to create a new get_unmapped_area_t. : static unsigned long : proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr, : unsigned long len, unsigned long pgoff, : unsigned long flags) : { : struct proc_dir_entry *pde = PDE(file_inode(file)); : unsigned long rv = -EIO; : : if (use_pde(pde)) { : typeof(proc_reg_get_unmapped_area) *get_area; : : get_area = pde->proc_fops->get_unmapped_area; : #ifdef CONFIG_MMU : if (!get_area) : get_area = current->mm->get_unmapped_area; : #endif : : if (get_area) : rv = get_area(file, orig_addr, len, pgoff, flags); : else : rv = orig_addr; : unuse_pde(pde); : } : return rv; : } --- a/fs/proc/inode.c~procfs-also-fix-proc_reg_get_unmapped_area-for-mmu-case-fix +++ a/fs/proc/inode.c @@ -294,17 +294,18 @@ proc_reg_get_unmapped_area(struct file * unsigned long rv = -EIO; if (use_pde(pde)) { - typeof(proc_reg_get_unmapped_area) *get_area + typeof(proc_reg_get_unmapped_area) *get_area; + + get_area = pde->proc_fops->get_unmapped_area; #ifdef CONFIG_MMU - = pde->proc_fops->get_unmapped_area - ?: current->mm->get_unmapped_area; -#else - = pde->proc_fops->get_unmapped_area; + if (!get_area) + get_area = current->mm->get_unmapped_area; #endif - rv = get_area - ? get_area(file, orig_addr, len, pgoff, flags) - : orig_addr; + if (get_area) + rv = get_area(file, orig_addr, len, pgoff, flags); + else + rv = orig_addr; unuse_pde(pde); } return rv; _