From patchwork Mon Jun 1 21:50:26 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Eric W. Biederman" X-Patchwork-Id: 27279 Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n51Lp6eb026560 for ; Mon, 1 Jun 2009 21:51:06 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754359AbZFAVvA (ORCPT ); Mon, 1 Jun 2009 17:51:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754383AbZFAVvA (ORCPT ); Mon, 1 Jun 2009 17:51:00 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:43309 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751615AbZFAVu5 (ORCPT ); Mon, 1 Jun 2009 17:50:57 -0400 Received: from in01.mta.xmission.com ([166.70.13.51]) by out01.mta.xmission.com with esmtp (Exim 4.62) (envelope-from ) id 1MBFPW-0007vV-V8; Mon, 01 Jun 2009 15:51:14 -0600 Received: from [76.21.114.89] (helo=fess.ebiederm.org) by in01.mta.xmission.com with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.69) (envelope-from ) id 1MBFPG-0002BQ-7f; Mon, 01 Jun 2009 15:50:58 -0600 Received: from fess.ebiederm.org (localhost [127.0.0.1]) by fess.ebiederm.org (8.14.3/8.14.3/Debian-4) with ESMTP id n51LotZY017065; Mon, 1 Jun 2009 14:50:55 -0700 Received: (from eric@localhost) by fess.ebiederm.org (8.14.3/8.14.3/Submit) id n51Lotja017064; Mon, 1 Jun 2009 14:50:55 -0700 From: "Eric W. Biederman" To: Al Viro Cc: , , , , Hugh Dickins , Tejun Heo , Alexey Dobriyan , Linus Torvalds , Alan Cox , Greg Kroah-Hartman , Nick Piggin , Andrew Morton , Christoph Hellwig , "Eric W. Biederman" , "Eric W. Biederman" Date: Mon, 1 Jun 2009 14:50:26 -0700 Message-Id: <1243893048-17031-1-git-send-email-ebiederm@xmission.com> X-Mailer: git-send-email 1.6.3.1.54.g99dd.dirty In-Reply-To: References: X-XM-SPF: eid=; ; ; mid=; ; ; hst=in01.mta.xmission.com; ; ; ip=76.21.114.89; ; ; frm=ebiederm@xmission.com; ; ; spf=neutral X-SA-Exim-Connect-IP: 76.21.114.89 X-SA-Exim-Rcpt-To: viro@ZenIV.linux.org.uk, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, hugh@veritas.com, tj@kernel.org, adobriyan@gmail.com, torvalds@linux-foundation.org, alan@lxorguk.ukuu.org.uk, gregkh@suse.de, npiggin@suse.de, akpm@linux-foundation.org, hch@infradead.org, ebiederm@xmission.com, ebiederm@aristanetworks.com X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-DCC: XMission; sa02 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on sa02.xmission.com X-Spam-Level: X-Spam-Status: No, score=-2.5 required=8.0 tests=ALL_TRUSTED,BAYES_00, DCC_CHECK_NEGATIVE, T_TM2_M_HEADER_IN_MSG, T_TooManySym_01, T_TooManySym_02, UNTRUSTED_Relay, XMNoVowels, XM_SPF_Neutral autolearn=disabled version=3.2.5 X-Spam-Combo: ;Al Viro X-Spam-Relay-Country: X-Spam-Report: * -1.8 ALL_TRUSTED Passed through trusted hosts only via SMTP * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -2.6 BAYES_00 BODY: Bayesian spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa02 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject * 0.0 XM_SPF_Neutral SPF-Neutral * 0.0 T_TooManySym_02 5+ unique symbols in subject * 0.4 UNTRUSTED_Relay Comes from a non-trusted relay Subject: [PATCH 01/23] mm: Introduce revoke_file_mappings. X-SA-Exim-Version: 4.2.1 (built Thu, 25 Oct 2007 00:26:12 +0000) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Eric W. Biederman When the backing store of a file becomes inaccessible we need a function to remove that file from the page tables and arrange for page faults to receive SIGBUS until the file is unmapped. Signed-off-by: Eric W. Biederman --- include/linux/mm.h | 2 + mm/memory.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 100 insertions(+), 0 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index bff1f0d..5d7480d 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -808,6 +808,8 @@ static inline void unmap_shared_mapping_range(struct address_space *mapping, extern int vmtruncate(struct inode * inode, loff_t offset); extern int vmtruncate_range(struct inode * inode, loff_t offset, loff_t end); +extern void revoke_file_mappings(struct file *file); + #ifdef CONFIG_MMU extern int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, int write_access); diff --git a/mm/memory.c b/mm/memory.c index 4126dd1..5cbee3b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -55,6 +55,7 @@ #include #include #include +#include #include #include @@ -2358,6 +2359,103 @@ void unmap_mapping_range(struct address_space *mapping, } EXPORT_SYMBOL(unmap_mapping_range); +static int revoked_fault(struct vm_area_struct *vma, struct vm_fault *vmf) +{ + return VM_FAULT_SIGBUS; +} + +static struct vm_operations_struct revoked_vm_ops = { + .fault = revoked_fault, +}; + +static void revoke_vma(struct vm_area_struct *vma) +{ + struct file *file = vma->vm_file; + struct address_space *mapping = file->f_mapping; + unsigned long start_addr, end_addr, size; + struct mm_struct *mm; + + start_addr = vma->vm_start; + end_addr = vma->vm_end; + + /* Switch out the locks so I can maninuplate this under the mm sem. + * Needed so I can call vm_ops->close. + */ + mm = vma->vm_mm; + atomic_inc(&mm->mm_users); + spin_unlock(&mapping->i_mmap_lock); + + /* Block page faults and other code modifying the mm. */ + down_write(&mm->mmap_sem); + + /* Lookup a vma for my file address */ + vma = find_vma(mm, start_addr); + if (vma->vm_file != file) + goto out; + + start_addr = vma->vm_start; + end_addr = vma->vm_end; + size = end_addr - start_addr; + + /* Unlock the pages */ + if (mm->locked_vm && (vma->vm_flags & VM_LOCKED)) { + mm->locked_vm -= vma_pages(vma); + vma->vm_flags &= ~VM_LOCKED; + } + + /* Unmap the vma */ + zap_page_range(vma, start_addr, size, NULL); + + /* Unlink the vma from the file */ + unlink_file_vma(vma); + + /* Close the vma */ + if (vma->vm_ops && vma->vm_ops->close) + vma->vm_ops->close(vma); + fput(vma->vm_file); + vma->vm_file = NULL; + if (vma->vm_flags & VM_EXECUTABLE) + removed_exe_file_vma(vma->vm_mm); + + /* Repurpose the vma */ + vma->vm_private_data = NULL; + vma->vm_ops = &revoked_vm_ops; + vma->vm_flags &= ~(VM_NONLINEAR | VM_CAN_NONLINEAR); +out: + up_write(&mm->mmap_sem); + spin_lock(&mapping->i_mmap_lock); +} + +void revoke_file_mappings(struct file *file) +{ + /* After a file has been marked dead update the vmas */ + struct address_space *mapping = file->f_mapping; + struct vm_area_struct *vma; + struct prio_tree_iter iter; + + spin_lock(&mapping->i_mmap_lock); + +restart_tree: + vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) { + /* Skip quickly over vmas that do not need to be touched */ + if (vma->vm_file != file) + continue; + revoke_vma(vma); + goto restart_tree; + } + +restart_list: + list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) { + /* Skip quickly over vmas that do not need to be touched */ + if (vma->vm_file != file) + continue; + revoke_vma(vma); + goto restart_list; + } + + spin_unlock(&mapping->i_mmap_lock); +} + /** * vmtruncate - unmap mappings "freed" by truncate() syscall * @inode: inode of the file used