Re: vm_area at addr ffffffffc0800000 is not marked as VM_IOREMAP

From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
	Christoph Hellwig <hch@infradead.org>,
	 Linus Torvalds <torvalds@linux-foundation.org>,
	linux-mm <linux-mm@kvack.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	 Linux ARM <linux-arm-kernel@lists.infradead.org>,
	 Daniel Borkmann <daniel@iogearbox.net>,
	bpf <bpf@vger.kernel.org>,  Bjorn Helgaas <bhelgaas@google.com>,
	linux-pci@vger.kernel.org
Subject: Re: vm_area at addr ffffffffc0800000 is not marked as VM_IOREMAP
Date: Thu, 7 Mar 2024 09:54:34 -0800	[thread overview]
Message-ID: <CAADnVQL1Zt5dwFv9HPDKDuPEKa6V7gb5j-D-LPWv47hC6mtwgw@mail.gmail.com> (raw)
In-Reply-To: <CANiq72ka4rir+RTN2FQoT=Vvprp_Ao-CvoYEkSNqtSY+RZj+AA@mail.gmail.com>

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 ]---