Hi Robin,
On Fri, Mar 8, 2019 at 2:53 PM Robin Murphy <robin.murphy@xxxxxxx> wrote:
> 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:
> __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@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>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> [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>
Thanks for the backport!
Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
