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

diff --git a/drivers/base/dd.c b/drivers/base/dd.c index ad44b40fe284..176c563a9739 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -861,9 +861,9 @@ static void __device_release_driver(struct device *dev, struct device *parent) 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)