releases/5.0.1/driver-core-postpone-dma-tear-down-until-after-devres-release.patch

   1 From 376991db4b6464e906d699ef07681e2ffa8ab08c Mon Sep 17 00:00:00 2001
   2 From: Geert Uytterhoeven <geert+renesas@glider.be>
   3 Date: Thu, 7 Feb 2019 20:36:53 +0100
   4 Subject: driver core: Postpone DMA tear-down until after devres release
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 From: Geert Uytterhoeven <geert+renesas@glider.be>
  10
  11 commit 376991db4b6464e906d699ef07681e2ffa8ab08c upstream.
  12
  13 When unbinding the (IOMMU-enabled) R-Car SATA device on Salvator-XS
  14 (R-Car H3 ES2.0), in preparation of rebinding against vfio-platform for
  15 device pass-through for virtualization:
  16
  17     echo ee300000.sata > /sys/bus/platform/drivers/sata_rcar/unbind
  18
  19 the kernel crashes with:
  20
  21     Unable to handle kernel paging request at virtual address ffffffbf029ffffc
  22     Mem abort info:
  23       ESR = 0x96000006
  24       Exception class = DABT (current EL), IL = 32 bits
  25       SET = 0, FnV = 0
  26       EA = 0, S1PTW = 0
  27     Data abort info:
  28       ISV = 0, ISS = 0x00000006
  29       CM = 0, WnR = 0
  30     swapper pgtable: 4k pages, 39-bit VAs, pgdp = 000000007e8c586c
  31     [ffffffbf029ffffc] pgd=000000073bfc6003, pud=000000073bfc6003, pmd=0000000000000000
  32     Internal error: Oops: 96000006 [#1] SMP
  33     Modules linked in:
  34     CPU: 0 PID: 1098 Comm: bash Not tainted 5.0.0-rc5-salvator-x-00452-g37596f884f4318ef #287
  35     Hardware name: Renesas Salvator-X 2nd version board based on r8a7795 ES2.0+ (DT)
  36     pstate: 60400005 (nZCv daif +PAN -UAO)
  37     pc : __free_pages+0x8/0x58
  38     lr : __dma_direct_free_pages+0x50/0x5c
  39     sp : ffffff801268baa0
  40     x29: ffffff801268baa0 x28: 0000000000000000
  41     x27: ffffffc6f9c60bf0 x26: ffffffc6f9c60bf0
  42     x25: ffffffc6f9c60810 x24: 0000000000000000
  43     x23: 00000000fffff000 x22: ffffff8012145000
  44     x21: 0000000000000800 x20: ffffffbf029fffc8
  45     x19: 0000000000000000 x18: ffffffc6f86c42c8
  46     x17: 0000000000000000 x16: 0000000000000070
  47     x15: 0000000000000003 x14: 0000000000000000
  48     x13: ffffff801103d7f8 x12: 0000000000000028
  49     x11: ffffff8011117604 x10: 0000000000009ad8
  50     x9 : ffffff80110126d0 x8 : ffffffc6f7563000
  51     x7 : 6b6b6b6b6b6b6b6b x6 : 0000000000000018
  52     x5 : ffffff8011cf3cc8 x4 : 0000000000004000
  53     x3 : 0000000000080000 x2 : 0000000000000001
  54     x1 : 0000000000000000 x0 : ffffffbf029fffc8
  55     Process bash (pid: 1098, stack limit = 0x00000000c38e3e32)
  56     Call trace:
  57      __free_pages+0x8/0x58
  58      __dma_direct_free_pages+0x50/0x5c
  59      arch_dma_free+0x1c/0x98
  60      dma_direct_free+0x14/0x24
  61      dma_free_attrs+0x9c/0xdc
  62      dmam_release+0x18/0x20
  63      release_nodes+0x25c/0x28c
  64      devres_release_all+0x48/0x4c
  65      device_release_driver_internal+0x184/0x1f0
  66      device_release_driver+0x14/0x1c
  67      unbind_store+0x70/0xb8
  68      drv_attr_store+0x24/0x34
  69      sysfs_kf_write+0x4c/0x64
  70      kernfs_fop_write+0x154/0x1c4
  71      __vfs_write+0x34/0x164
  72      vfs_write+0xb4/0x16c
  73      ksys_write+0x5c/0xbc
  74      __arm64_sys_write+0x14/0x1c
  75      el0_svc_common+0x98/0x114
  76      el0_svc_handler+0x1c/0x24
  77      el0_svc+0x8/0xc
  78     Code: d51b4234 17fffffa a9bf7bfd 910003fd (b9403404)
  79     ---[ end trace 8c564cdd3a1a840f ]---
  80
  81 While I've bisected this to commit e8e683ae9a736407 ("iommu/of: Fix
  82 probe-deferral"), and reverting that commit on post-v5.0-rc4 kernels
  83 does fix the problem, this turned out to be a red herring.
  84
  85 On arm64, arch_teardown_dma_ops() resets dev->dma_ops to NULL.
  86 Hence if a driver has used a managed DMA allocation API, the allocated
  87 DMA memory will be freed using the direct DMA ops, while it may have
  88 been allocated using a custom DMA ops (iommu_dma_ops in this case).
  89
  90 Fix this by reversing the order of the calls to devres_release_all() and
  91 arch_teardown_dma_ops().
  92
  93 Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
  94 Acked-by: Christoph Hellwig <hch@lst.de>
  95 Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
  96 Cc: stable <stable@vger.kernel.org>
  97 Reviewed-by: Robin Murphy <robin.murphy@arm.com>
  98 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  99
 100 ---
 101  drivers/base/dd.c |    2 +-
 102  1 file changed, 1 insertion(+), 1 deletion(-)
 103
 104 --- a/drivers/base/dd.c
 105 +++ b/drivers/base/dd.c
 106 @@ -968,9 +968,9 @@ static void __device_release_driver(stru
 107                         drv->remove(dev);
 108
 109                 device_links_driver_cleanup(dev);
 110 -               arch_teardown_dma_ops(dev);
 111
 112                 devres_release_all(dev);
 113 +               arch_teardown_dma_ops(dev);
 114                 dev->driver = NULL;
 115                 dev_set_drvdata(dev, NULL);
 116                 if (dev->pm_domain && dev->pm_domain->dismiss)