Linux-PCI Archive on lore.kernel.org
 help / color / Atom feed
From: Dexuan Cui <decui@microsoft.com>
To: "lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>,
	"bhelgaas@google.com" <bhelgaas@google.com>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	KY Srinivasan <kys@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	Michael Kelley <mikelley@microsoft.com>,
	Sasha Levin <Alexander.Levin@microsoft.com>
Cc: "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"driverdev-devel@linuxdriverproject.org" 
	<driverdev-devel@linuxdriverproject.org>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	"olaf@aepfle.de" <olaf@aepfle.de>,
	"apw@canonical.com" <apw@canonical.com>,
	"jasowang@redhat.com" <jasowang@redhat.com>,
	vkuznets <vkuznets@redhat.com>,
	"marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com>,
	"jackm@mellanox.com" <jackm@mellanox.com>,
	Dexuan Cui <decui@microsoft.com>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: [PATCH 1/3] PCI: hv: Fix a memory leak in hv_eject_device_work()
Date: Mon, 4 Mar 2019 21:34:48 +0000
Message-ID: <20190304213357.16652-2-decui@microsoft.com> (raw)
In-Reply-To: <20190304213357.16652-1-decui@microsoft.com>

After a device is just created in new_pcichild_device(), hpdev->refs is set
to 2 (i.e. the initial value of 1 plus the get_pcichild()).

When we hot remove the device from the host, in Linux VM we first call
hv_pci_eject_device(), which increases hpdev->refs by get_pcichild() and
then schedules a work of hv_eject_device_work(), so hpdev->refs becomes 3
(let's ignore the paired get/put_pcichild() in other places). But in
hv_eject_device_work(), currently we only call put_pcichild() twice,
meaning the 'hpdev' struct can't be freed in put_pcichild(). This patch
adds one put_pcichild() to fix the memory leak.

BTW, the device can also be removed when we run "rmmod pci-hyperv". On this
path (hv_pci_remove() -> hv_pci_bus_exit() -> hv_pci_devices_present()),
hpdev->refs is 2, and we do correctly call put_pcichild() twice in
pci_devices_present_work().

Fixes: 4daace0d8ce8 ("PCI: hv: Add paravirtual PCI front-end for Microsoft Hyper-V VMs")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Cc: <stable@vger.kernel.org>
---
 drivers/pci/controller/pci-hyperv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 95441a35eceb..30f16b882746 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -1900,6 +1900,9 @@ static void hv_eject_device_work(struct work_struct *work)
 			 sizeof(*ejct_pkt), (unsigned long)&ctxt.pkt,
 			 VM_PKT_DATA_INBAND, 0);
 
+	/* For the get_pcichild() in hv_pci_eject_device() */
+	put_pcichild(hpdev);
+	/* For the two refs got in new_pcichild_device() */
 	put_pcichild(hpdev);
 	put_pcichild(hpdev);
 	put_hvpcibus(hpdev->hbus);
-- 
2.19.1


  reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-04 21:34 [PATCH 0/3] pci-hyperv: fix memory leak and add pci_destroy_slot() Dexuan Cui
2019-03-04 21:34 ` Dexuan Cui [this message]
2019-03-20 21:37   ` [PATCH 1/3] PCI: hv: Fix a memory leak in hv_eject_device_work() Michael Kelley
2019-03-21  0:12     ` Dexuan Cui
2019-03-26 17:08       ` Lorenzo Pieralisi
2019-03-26 17:47         ` Michael Kelley
2019-03-26 18:01           ` Dexuan Cui
2019-03-26 18:12             ` Lorenzo Pieralisi
2019-03-04 21:34 ` [PATCH 2/3] PCI: hv: Add hv_pci_remove_slots() when we unload the driver Dexuan Cui
2019-03-20 21:38   ` Michael Kelley
2019-03-04 21:34 ` [PATCH 3/3] PCI: hv: Add pci_destroy_slot() in pci_devices_present_work(), if necessary Dexuan Cui
2019-03-20 21:44   ` Michael Kelley
2019-03-21  0:35     ` Dexuan Cui
2019-03-21  0:42       ` Dexuan Cui
2019-03-26 17:50       ` Michael Kelley
2019-03-26 19:54   ` Lorenzo Pieralisi
2019-03-27  0:22     ` Dexuan Cui
2019-03-05 18:27 ` [PATCH 0/3] pci-hyperv: fix memory leak and add pci_destroy_slot() Stephen Hemminger

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190304213357.16652-2-decui@microsoft.com \
    --to=decui@microsoft.com \
    --cc=Alexander.Levin@microsoft.com \
    --cc=apw@canonical.com \
    --cc=bhelgaas@google.com \
    --cc=driverdev-devel@linuxdriverproject.org \
    --cc=haiyangz@microsoft.com \
    --cc=jackm@mellanox.com \
    --cc=jasowang@redhat.com \
    --cc=kys@microsoft.com \
    --cc=linux-hyperv@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=lorenzo.pieralisi@arm.com \
    --cc=marcelo.cerri@canonical.com \
    --cc=mikelley@microsoft.com \
    --cc=olaf@aepfle.de \
    --cc=stable@vger.kernel.org \
    --cc=sthemmin@microsoft.com \
    --cc=vkuznets@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-PCI Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-pci/0 linux-pci/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-pci linux-pci/ https://lore.kernel.org/linux-pci \
		linux-pci@vger.kernel.org
	public-inbox-index linux-pci

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-pci


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git