From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753612Ab1AJKf4 (ORCPT ); Mon, 10 Jan 2011 05:35:56 -0500 Received: from smtp02.citrix.com ([66.165.176.63]:36877 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753556Ab1AJKfw (ORCPT ); Mon, 10 Jan 2011 05:35:52 -0500 X-IronPort-AV: E=Sophos;i="4.60,299,1291611600"; d="scan'208";a="130293795" From: stefano.stabellini@eu.citrix.com To: linux-kernel@vger.kernel.org Cc: xen-devel@lists.xensource.com, Jeremy.Fitzhardinge@citrix.com, konrad.wilk@oracle.com, Daniel De Graaf Subject: [PATCH 08/12] xen/gntdev: Fix circular locking dependency Date: Mon, 10 Jan 2011 10:36:37 +0000 Message-Id: <1294655801-16230-8-git-send-email-stefano.stabellini@eu.citrix.com> X-Mailer: git-send-email 1.7.0.4 In-Reply-To: References: X-OriginalArrivalTime: 10 Jan 2011 10:35:52.0080 (UTC) FILETIME=[2755E900:01CBB0B2] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Daniel De Graaf apply_to_page_range will acquire PTE lock while priv->lock is held, and mn_invl_range_start tries to acquire priv->lock with PTE already held. Fix by not holding priv->lock during the entire map operation. This is safe because map->vma is set nonzero while the lock is held, which will cause subsequent maps to fail and will cause the unmap ioctl (and other users of gntdev_del_map) to return -EBUSY until the area is unmapped. It is similarly impossible for gntdev_vma_close to be called while the vma is still being created. Signed-off-by: Daniel De Graaf --- drivers/xen/gntdev.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index a2ea533..aba76d4 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -575,21 +575,26 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) if (!(vma->vm_flags & VM_WRITE)) map->flags |= GNTMAP_readonly; + spin_unlock(&priv->lock); + err = apply_to_page_range(vma->vm_mm, vma->vm_start, vma->vm_end - vma->vm_start, find_grant_ptes, map); if (err) { printk(KERN_WARNING "find_grant_ptes() failure.\n"); - goto unlock_out; + return err; } err = map_grant_pages(map); if (err) { printk(KERN_WARNING "map_grant_pages() failure.\n"); - goto unlock_out; + return err; } + map->is_mapped = 1; + return 0; + unlock_out: spin_unlock(&priv->lock); return err; -- 1.5.6.5