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The cited patch change mlx5 driver so that during probe DMA
operations were performed before pci_enable_device(), and during
teardown DMA operations were performed after pci_disable_device().
DMA operations require PCI to be enabled. Hence, The above leads to
the following oops in PPC systems[1].
On s390x systems, as reported by Niklas Schnelle, this is a problem
because mlx5_pci_init() is where the DMA and coherent mask is set but
mlx5_cmd_init() already does a dma_alloc_coherent(). Thus a DMA
allocation is done during probe before the correct mask is set. This
causes probe to fail initialization of the cmdif SW structs on s390x
after that is converted to the common dma-iommu code. This is because on
s390x DMA addresses below 4 GiB are reserved on current machines and
unlike the old s390x specific DMA API implementation common code
enforces DMA masks.
Fix it by performing the DMA operations during probe after
pci_enable_device() and after the dma mask is set,
and during teardown before pci_disable_device().
[1]
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
Modules linked in: xt_MASQUERADE nf_conntrack_netlink
nfnetlink xfrm_user iptable_nat xt_addrtype xt_conntrack nf_nat
nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 netconsole rpcsec_gss_krb5
auth_rpcgss oid_registry overlay rpcrdma rdma_ucm ib_iser ib_umad
rdma_cm ib_ipoib iw_cm libiscsi scsi_transport_iscsi ib_cm ib_uverbs
ib_core mlx5_core(-) ptp pps_core fuse vmx_crypto crc32c_vpmsum [last
unloaded: mlx5_ib]
CPU: 1 PID: 8937 Comm: modprobe Not tainted 6.5.0-rc3_for_upstream_min_debug_2023_07_31_16_02 #1
Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries
NIP: c000000000423388 LR: c0000000001e733c CTR: c0000000001e4720
REGS: c0000000055636d0 TRAP: 0380 Not tainted (6.5.0-rc3_for_upstream_min_debug_2023_07_31_16_02)
MSR: 8000000000009033 CR: 24008884 XER: 20040000
CFAR: c0000000001e7338 IRQMASK: 0
NIP [c000000000423388] __free_pages+0x28/0x160
LR [c0000000001e733c] dma_direct_free+0xac/0x190
Call Trace:
[c000000005563970] [5deadbeef0000100] 0x5deadbeef0000100 (unreliable)
[c0000000055639b0] [c0000000003d46cc] kfree+0x7c/0x150
[c000000005563a40] [c0000000001e47c8] dma_free_attrs+0xa8/0x1a0
[c000000005563aa0] [c008000000d0064c] mlx5_cmd_cleanup+0xa4/0x100 [mlx5_core]
[c000000005563ad0] [c008000000cf629c] mlx5_mdev_uninit+0xf4/0x140 [mlx5_core]
[c000000005563b00] [c008000000cf6448] remove_one+0x160/0x1d0 [mlx5_core]
[c000000005563b40] [c000000000958540] pci_device_remove+0x60/0x110
[c000000005563b80] [c000000000a35e80] device_remove+0x70/0xd0
[c000000005563bb0] [c000000000a37a38] device_release_driver_internal+0x2a8/0x330
[c000000005563c00] [c000000000a37b8c] driver_detach+0x8c/0x160
[c000000005563c40] [c000000000a35350] bus_remove_driver+0x90/0x110
[c000000005563c80] [c000000000a38948] driver_unregister+0x48/0x90
[c000000005563cf0] [c000000000957e38] pci_unregister_driver+0x38/0x150
[c000000005563d40] [c008000000eb6140] mlx5_cleanup+0x38/0x90 [mlx5_core]
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.