Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932928AbcCVLUH (ORCPT ); Tue, 22 Mar 2016 07:20:07 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:56483 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758689AbcCVKlx (ORCPT ); Tue, 22 Mar 2016 06:41:53 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Konrad Rzeszutek Wilk , David Vrabel , Luis Henriques Subject: [PATCH 3.16.y-ckt 030/142] xen/pcifront: Fix mysterious crashes when NUMA locality information was extracted. Date: Tue, 22 Mar 2016 10:39:19 +0000 Message-Id: <1458643271-4227-31-git-send-email-luis.henriques@canonical.com> In-Reply-To: <1458643271-4227-1-git-send-email-luis.henriques@canonical.com> References: <1458643271-4227-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3969 Lines: 111 3.16.7-ckt26 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Konrad Rzeszutek Wilk commit 4d8c8bd6f2062c9988817183a91fe2e623c8aa5e upstream. Occasionaly PV guests would crash with: pciback 0000:00:00.1: Xen PCI mapped GSI0 to IRQ16 BUG: unable to handle kernel paging request at 0000000d1a8c0be0 .. snip.. ] find_next_bit+0xb/0x10 [] cpumask_next_and+0x22/0x40 [] pci_device_probe+0xb8/0x120 [] ? driver_sysfs_add+0x77/0xa0 [] driver_probe_device+0x1a4/0x2d0 [] ? pci_match_device+0xdd/0x110 [] __device_attach_driver+0xa7/0xb0 [] ? __driver_attach+0xa0/0xa0 [] bus_for_each_drv+0x62/0x90 [] __device_attach+0xbd/0x110 [] device_attach+0xb/0x10 [] pci_bus_add_device+0x3c/0x70 [] pci_bus_add_devices+0x38/0x80 [] pcifront_scan_root+0x13e/0x1a0 [] pcifront_backend_changed+0x262/0x60b [] ? xenbus_gather+0xd6/0x160 [] ? put_object+0x2f/0x50 [] xenbus_otherend_changed+0x9d/0xa0 [] backend_changed+0xe/0x10 [] xenwatch_thread+0xc8/0x190 [] ? woken_wake_function+0x10/0x10 which was the result of two things: When we call pci_scan_root_bus we would pass in 'sd' (sysdata) pointer which was an 'pcifront_sd' structure. However in the pci_device_add it expects that the 'sd' is 'struct sysdata' and sets the dev->node to what is in sd->node (offset 4): set_dev_node(&dev->dev, pcibus_to_node(bus)); __pcibus_to_node(const struct pci_bus *bus) { const struct pci_sysdata *sd = bus->sysdata; return sd->node; } However our structure was pcifront_sd which had nothing at that offset: struct pcifront_sd { int domain; /* 0 4 */ /* XXX 4 bytes hole, try to pack */ struct pcifront_device * pdev; /* 8 8 */ } That is an hole - filled with garbage as we used kmalloc instead of kzalloc (the second problem). This patch fixes the issue by: 1) Use kzalloc to initialize to a well known state. 2) Put 'struct pci_sysdata' at the start of 'pcifront_sd'. That way access to the 'node' will access the right offset. Signed-off-by: Konrad Rzeszutek Wilk Reviewed-by: Boris Ostrovsky Signed-off-by: David Vrabel Signed-off-by: Luis Henriques --- drivers/pci/xen-pcifront.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c index 53df39a22c8a..626360b07701 100644 --- a/drivers/pci/xen-pcifront.c +++ b/drivers/pci/xen-pcifront.c @@ -52,7 +52,7 @@ struct pcifront_device { }; struct pcifront_sd { - int domain; + struct pci_sysdata sd; struct pcifront_device *pdev; }; @@ -66,7 +66,9 @@ static inline void pcifront_init_sd(struct pcifront_sd *sd, unsigned int domain, unsigned int bus, struct pcifront_device *pdev) { - sd->domain = domain; + /* Because we do not expose that information via XenBus. */ + sd->sd.node = first_online_node; + sd->sd.domain = domain; sd->pdev = pdev; } @@ -464,8 +466,8 @@ static int pcifront_scan_root(struct pcifront_device *pdev, dev_info(&pdev->xdev->dev, "Creating PCI Frontend Bus %04x:%02x\n", domain, bus); - bus_entry = kmalloc(sizeof(*bus_entry), GFP_KERNEL); - sd = kmalloc(sizeof(*sd), GFP_KERNEL); + bus_entry = kzalloc(sizeof(*bus_entry), GFP_KERNEL); + sd = kzalloc(sizeof(*sd), GFP_KERNEL); if (!bus_entry || !sd) { err = -ENOMEM; goto err_out;