[PATCH 4.19 145/149] driver core: Postpone DMA tear-down until after devres release

[Greg Kroah-Hartman]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

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:
  Â__free_pages+0x8/0x58
  Â__dma_direct_free_pages+0x50/0x5c
  Âarch_dma_free+0x1c/0x98
  Âdma_direct_free+0x14/0x24
  Âdma_free_attrs+0x9c/0xdc
  Âdmam_release+0x18/0x20
  Ârelease_nodes+0x25c/0x28c
  Âdevres_release_all+0x48/0x4c
  Âdevice_release_driver_internal+0x184/0x1f0
  Âdevice_release_driver+0x14/0x1c
  Âunbind_store+0x70/0xb8
  Âdrv_attr_store+0x24/0x34
  Âsysfs_kf_write+0x4c/0x64
  Âkernfs_fop_write+0x154/0x1c4
  Â__vfs_write+0x34/0x164
  Âvfs_write+0xb4/0x16c
  Âksys_write+0x5c/0xbc
  Â__arm64_sys_write+0x14/0x1c
  Âel0_svc_common+0x98/0x114
  Âel0_svc_handler+0x1c/0x24
  Âel0_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@xxxxxxxxx>
Acked-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
[rm: backport for 4.12-4.19 - kernels before 5.0 will not see
 the crash above, but may get silent memory corruption instead]
Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -963,9 +963,9 @@ static void __device_release_driver(stru
 			drv->remove(dev);
 
 		device_links_driver_cleanup(dev);
-		dma_deconfigure(dev);
 
 		devres_release_all(dev);
+		dma_deconfigure(dev);
 		dev->driver = NULL;
 		dev_set_drvdata(dev, NULL);
 		if (dev->pm_domain && dev->pm_domain->dismiss)