[PATCH 4.20 07/76] driver core: Postpone DMA tear-down until after devres release

Greg Kroah-Hartman
2019-03-08T13:07:01Z

From: Geert Uytterhoeven <geert+renesas@glider.be>

commit 376991db4b6464e906d699ef07681e2ffa8ab08c upstream.

When unbinding the (IOMMU-enabled) R-Car SATA device on Salvator-XS
(R-Car H3 ES2.0), in preparation of rebinding against vfio-platform for
device pass-through for virtualization:

echo ee300000.sata > /sys/bus/platform/drivers/sata_rcar/unbind

the kernel crashes with:

Unable to handle kernel paging request at virtual address ffffffbf029ffffc
Mem abort info:
ESR = 0x96000006
Exception class = DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
Data abort info:
ISV = 0, ISS = 0x00000006
CM = 0, WnR = 0
swapper pgtable: 4k pages, 39-bit VAs, pgdp = 000000007e8c586c
[ffffffbf029ffffc] pgd=000000073bfc6003, pud=000000073bfc6003, pmd=0000000000000000
Internal error: Oops: 96000006 [#1] SMP
Modules linked in:
CPU: 0 PID: 1098 Comm: bash Not tainted 5.0.0-rc5-salvator-x-00452-g37596f884f4318ef #287
Hardware name: Renesas Salvator-X 2nd version board based on r8a7795 ES2.0+ (DT)
pstate: 60400005 (nZCv daif +PAN -UAO)
pc : __free_pages+0x8/0x58
lr : __dma_direct_free_pages+0x50/0x5c
sp : ffffff801268baa0
x29: ffffff801268baa0 x28: 0000000000000000
x27: ffffffc6f9c60bf0 x26: ffffffc6f9c60bf0
x25: ffffffc6f9c60810 x24: 0000000000000000
x23: 00000000fffff000 x22: ffffff8012145000
x21: 0000000000000800 x20: ffffffbf029fffc8
x19: 0000000000000000 x18: ffffffc6f86c42c8
x17: 0000000000000000 x16: 0000000000000070
x15: 0000000000000003 x14: 0000000000000000
x13: ffffff801103d7f8 x12: 0000000000000028
x11: ffffff8011117604 x10: 0000000000009ad8
x9 : ffffff80110126d0 x8 : ffffffc6f7563000
x7 : 6b6b6b6b6b6b6b6b x6 : 0000000000000018
x5 : ffffff8011cf3cc8 x4 : 0000000000004000
x3 : 0000000000080000 x2 : 0000000000000001
x1 : 0000000000000000 x0 : ffffffbf029fffc8
Process bash (pid: 1098, stack limit = 0x00000000c38e3e32)
Call trace:
__free_pages+0x8/0x58
__dma_direct_free_pages+0x50/0x5c
arch_dma_free+0x1c/0x98
dma_direct_free+0x14/0x24
dma_free_attrs+0x9c/0xdc
dmam_release+0x18/0x20
release_nodes+0x25c/0x28c
devres_release_all+0x48/0x4c
device_release_driver_internal+0x184/0x1f0
device_release_driver+0x14/0x1c
unbind_store+0x70/0xb8
drv_attr_store+0x24/0x34
sysfs_kf_write+0x4c/0x64
kernfs_fop_write+0x154/0x1c4
__vfs_write+0x34/0x164
vfs_write+0xb4/0x16c
ksys_write+0x5c/0xbc
__arm64_sys_write+0x14/0x1c
el0_svc_common+0x98/0x114
el0_svc_handler+0x1c/0x24
el0_svc+0x8/0xc
Code: d51b4234 17fffffa a9bf7bfd 910003fd (b9403404)
---[ end trace 8c564cdd3a1a840f ]---

While I've bisected this to commit e8e683ae9a736407 ("iommu/of: Fix
probe-deferral"), and reverting that commit on post-v5.0-rc4 kernels
does fix the problem, this turned out to be a red herring.

On arm64, arch_teardown_dma_ops() resets dev->dma_ops to NULL.
Hence if a driver has used a managed DMA allocation API, the allocated
DMA memory will be freed using the direct DMA ops, while it may have
been allocated using a custom DMA ops (iommu_dma_ops in this case).

Fix this by reversing the order of the calls to devres_release_all() and
arch_teardown_dma_ops().

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/base/dd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -965,9 +965,9 @@ static void __device_release_driver(stru
drv->remove(dev);

device_links_driver_cleanup(dev);
- arch_teardown_dma_ops(dev);

devres_release_all(dev);
+ arch_teardown_dma_ops(dev);
dev->driver = NULL;
dev_set_drvdata(dev, NULL);
if (dev->pm_domain && dev->pm_domain->dismiss)