Re: vm_area at addr ffffffffc0800000 is not marked as VM_IOREMAP

Alexei Starovoitov
2024-03-07T17:54:49Z

On Thu, Mar 7, 2024 at 9:42 AM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> Hi arm64/bpf/pci,
>
> In today's next-20240307 with a defconfig LLVM=1 I am seeing [1] under
> QEMU virt, i.e. from
> https://lore.kernel.org/all/20240305030516.41519-2-alexei.starovoitov@gmail.com/
> applied to the bpf-next tree.
>
> Cheers,
> Miguel
>
> [1]
>
> [ 0.425177] pci-host-generic 4010000000.pcie: host bridge
> /pcie@10000000 ranges:
> [ 0.425886] pci-host-generic 4010000000.pcie: IO
> 0x003eff0000..0x003effffff -> 0x0000000000
> [ 0.426534] pci-host-generic 4010000000.pcie: MEM
> 0x0010000000..0x003efeffff -> 0x0010000000
> [ 0.426764] pci-host-generic 4010000000.pcie: MEM
> 0x8000000000..0xffffffffff -> 0x8000000000
> [ 0.427324] ------------[ cut here ]------------
> [ 0.427456] vm_area at addr ffffffffc0800000 is not marked as VM_IOREMAP
> [ 0.427944] WARNING: CPU: 0 PID: 1 at mm/vmalloc.c:315
> ioremap_page_range+0x25c/0x2bc

Great. Thanks for flagging.
Looks like this check found some misuse of ioremap_page_range.

Note that without marking the address range as VM_IOREMAP
the vread_iter() will be bulk reading over IO and might
cause hard hangs and what not.
pci drivers need to mark their range as VM_IOREMAP.
That was the reason for the warning.

I'll try to figure out which piece of code missed passing
VM_IOREMAP into vm_area.
I'm not familiar with pci, so help is greatly appreciated.

> [ 0.429236] CPU: 0 PID: 1 Comm: swapper/0 Not tainted
> 6.8.0-rc7-next-20240307 #1
> [ 0.429513] Hardware name: linux,dummy-virt (DT)
> [ 0.429751] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [ 0.429946] pc : ioremap_page_range+0x25c/0x2bc
> [ 0.430063] lr : ioremap_page_range+0x258/0x2bc
> [ 0.432220] Call trace:
> [ 0.432462] ioremap_page_range+0x25c/0x2bc
> [ 0.432703] pci_remap_iospace+0x78/0x84
> [ 0.432854] devm_pci_remap_iospace+0x54/0x98
> [ 0.432979] devm_of_pci_bridge_init+0x2e0/0x48c
> [ 0.433114] devm_pci_alloc_host_bridge+0xa4/0xbc
> [ 0.433254] pci_host_common_probe+0x48/0x1a4
> [ 0.433363] platform_probe+0xa8/0xd0
> [ 0.433456] really_probe+0x130/0x2e4
> [ 0.433545] __driver_probe_device+0xa0/0x128
> [ 0.433647] driver_probe_device+0x3c/0x1f8
> [ 0.433742] __driver_attach+0xdc/0x1a4
> [ 0.433834] bus_for_each_dev+0xe8/0x140
> [ 0.433925] driver_attach+0x24/0x30
> [ 0.434011] bus_add_driver+0x154/0x240
> [ 0.434104] driver_register+0x68/0x100
> [ 0.434196] __platform_driver_register+0x24/0x30
> [ 0.434306] gen_pci_driver_init+0x1c/0x28
> [ 0.434407] do_one_initcall+0xbc/0x248
> [ 0.434533] do_initcall_level+0x94/0xb4
> [ 0.434632] do_initcalls+0x54/0x94
> [ 0.434721] do_basic_setup+0x50/0x60
> [ 0.434810] kernel_init_freeable+0x10c/0x178
> [ 0.434912] kernel_init+0x20/0x1a0
> [ 0.435003] ret_from_fork+0x10/0x20
> [ 0.435227] ---[ end trace 0000000000000000 ]---