From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: Ira Weiny <ira.weiny@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>, <linux-cxl@vger.kernel.org>
Subject: Re: [PATCH v2 4/4] cxl/mem: Fix shutdown order
Date: Mon, 2 Oct 2023 11:11:31 +0100 [thread overview]
Message-ID: <20231002111131.00001e59@Huawei.com> (raw)
In-Reply-To: <65176326ddc98_168c46294e8@iweiny-mobl.notmuch>
On Fri, 29 Sep 2023 16:52:06 -0700
Ira Weiny <ira.weiny@intel.com> wrote:
> Dan Williams wrote:
> > Ira reports that removing cxl_mock_mem causes a crash with the following
> > trace:
> >
> > BUG: kernel NULL pointer dereference, address: 0000000000000044
> > [..]
> > RIP: 0010:cxl_region_decode_reset+0x7f/0x180 [cxl_core]
> > [..]
> > Call Trace:
> > <TASK>
> > cxl_region_detach+0xe8/0x210 [cxl_core]
> > cxl_decoder_kill_region+0x27/0x40 [cxl_core]
> > cxld_unregister+0x29/0x40 [cxl_core]
> > devres_release_all+0xb8/0x110
> > device_unbind_cleanup+0xe/0x70
> > device_release_driver_internal+0x1d2/0x210
> > bus_remove_device+0xd7/0x150
> > device_del+0x155/0x3e0
> > device_unregister+0x13/0x60
> > devm_release_action+0x4d/0x90
> > ? __pfx_unregister_port+0x10/0x10 [cxl_core]
> > delete_endpoint+0x121/0x130 [cxl_core]
> > devres_release_all+0xb8/0x110
> > device_unbind_cleanup+0xe/0x70
> > device_release_driver_internal+0x1d2/0x210
> > bus_remove_device+0xd7/0x150
> > device_del+0x155/0x3e0
> > ? lock_release+0x142/0x290
> > cdev_device_del+0x15/0x50
> > cxl_memdev_unregister+0x54/0x70 [cxl_core]
> >
> > This crash is due to the clearing out the cxl_memdev's driver context
> > (@cxlds) before the subsystem is done with it. This is ultimately due to
> > the region(s), that this memdev is a member, being torn down and expecting
> > to be able to de-reference @cxlds, like here:
> >
> > static int cxl_region_decode_reset(struct cxl_region *cxlr, int count)
> > ...
> > if (cxlds->rcd)
> > goto endpoint_reset;
> > ...
> >
> > Fix it by keeping the driver context valid until memdev-device
> > unregistration, and subsequently the entire stack of related
> > dependencies, unwinds.
> >
> > Fixes: 9cc238c7a526 ("cxl/pci: Introduce cdevm_file_operations")
> > Reported-by: Ira Weiny <ira.weiny@intel.com>
>
> Reviewed-by: Ira Weiny <ira.weiny@intel.com>
> Tested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Thanks for cleaning up the whole area whilst fixing this.
Jonathan
next prev parent reply other threads:[~2023-10-02 10:11 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-29 23:09 [PATCH v2 0/4] cxl/mem: Fix shutdown order Dan Williams
2023-09-29 23:09 ` [PATCH v2 1/4] cxl/pci: Remove unnecessary device reference management in sanitize work Dan Williams
2023-09-29 23:41 ` Ira Weiny
2023-10-02 9:55 ` Jonathan Cameron
2023-10-02 15:27 ` Davidlohr Bueso
2023-10-02 16:48 ` Dave Jiang
2023-09-29 23:09 ` [PATCH v2 2/4] cxl/pci: Cleanup 'sanitize' to always poll Dan Williams
2023-09-29 23:49 ` Ira Weiny
2023-09-29 23:51 ` Ira Weiny
2023-10-02 10:02 ` Jonathan Cameron
2023-10-04 0:55 ` Dan Williams
2023-10-02 15:49 ` Davidlohr Bueso
2023-10-04 1:01 ` Dan Williams
2023-10-04 1:13 ` Davidlohr Bueso
2023-10-02 16:57 ` Dave Jiang
2023-09-29 23:09 ` [PATCH v2 3/4] cxl/pci: Fix sanitize notifier setup Dan Williams
2023-09-30 2:42 ` Ira Weiny
2023-10-02 10:10 ` Jonathan Cameron
2023-10-04 0:59 ` Dan Williams
2023-10-04 10:12 ` Jonathan Cameron
2023-10-04 18:47 ` Dan Williams
2023-10-02 16:59 ` Dave Jiang
2023-10-04 0:52 ` Davidlohr Bueso
2023-10-04 1:09 ` Dan Williams
2023-10-04 16:21 ` Davidlohr Bueso
2023-10-04 18:48 ` Dan Williams
2023-10-04 18:50 ` Dan Williams
2023-10-04 18:54 ` Dan Williams
2023-10-04 19:23 ` Davidlohr Bueso
2023-09-29 23:09 ` [PATCH v2 4/4] cxl/mem: Fix shutdown order Dan Williams
2023-09-29 23:52 ` Ira Weiny
2023-10-02 10:11 ` Jonathan Cameron [this message]
2023-10-02 16:59 ` Dave Jiang
2023-10-03 17:40 ` Davidlohr Bueso
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