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[v4,bpf-next,0/2] mm: Enforce ioremap address space and introduce sparse vm_area

Message ID 20240305030516.41519-1-alexei.starovoitov@gmail.com (mailing list archive)
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Series mm: Enforce ioremap address space and introduce sparse vm_area | expand

Message

Alexei Starovoitov March 5, 2024, 3:05 a.m. UTC 
From: Alexei Starovoitov <ast@kernel.org>

v3 -> v4
- dropped VM_XEN patch for now. It will be in the follow up.
- fixed constant as pointed out by Mike

v2 -> v3
- added Christoph's reviewed-by to patch 1
- cap commit log lines to 75 chars
- factored out common checks in patch 3 into helper
- made vm_area_unmap_pages() return void

There are various users of kernel virtual address space:
vmalloc, vmap, ioremap, xen.

- vmalloc use case dominates the usage. Such vm areas have VM_ALLOC flag
and these areas are treated differently by KASAN.

- the areas created by vmap() function should be tagged with VM_MAP
(as majority of the users do).

- ioremap areas are tagged with VM_IOREMAP and vm area start is aligned
to size of the area unlike vmalloc/vmap.

- there is also xen usage that is marked as VM_IOREMAP, but it doesn't
call ioremap_page_range() unlike all other VM_IOREMAP users.

To clean this up a bit, enforce that ioremap_page_range() checks the range
and VM_IOREMAP flag.

In addition BPF would like to reserve regions of kernel virtual address
space and populate it lazily, similar to xen use cases.
For that reason, introduce VM_SPARSE flag and vm_area_[un]map_pages()
helpers to populate this sparse area.

In the end the /proc/vmallocinfo will show
"vmalloc"
"vmap"
"ioremap"
"sparse"
categories for different kinds of address regions.

ioremap, sparse will return zero when dumped through /proc/kcore

Alexei Starovoitov (2):
  mm: Enforce VM_IOREMAP flag and range in ioremap_page_range.
  mm: Introduce VM_SPARSE kind and vm_area_[un]map_pages().

 include/linux/vmalloc.h |  5 +++
 mm/vmalloc.c            | 72 +++++++++++++++++++++++++++++++++++++++--
 2 files changed, 75 insertions(+), 2 deletions(-)

Comments

patchwork-bot+netdevbpf@kernel.org March 6, 2024, 6:30 p.m. UTC | #1 
Hello:

This series was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Mon,  4 Mar 2024 19:05:14 -0800 you wrote:
> From: Alexei Starovoitov <ast@kernel.org>
> 
> v3 -> v4
> - dropped VM_XEN patch for now. It will be in the follow up.
> - fixed constant as pointed out by Mike
> 
> v2 -> v3
> - added Christoph's reviewed-by to patch 1
> - cap commit log lines to 75 chars
> - factored out common checks in patch 3 into helper
> - made vm_area_unmap_pages() return void
> 
> [...]

Here is the summary with links:
  - [v4,bpf-next,1/2] mm: Enforce VM_IOREMAP flag and range in ioremap_page_range.
    https://git.kernel.org/bpf/bpf-next/c/3e49a866c9dc
  - [v4,bpf-next,2/2] mm: Introduce VM_SPARSE kind and vm_area_[un]map_pages().
    https://git.kernel.org/bpf/bpf-next/c/6b66b3a4ed5e

You are awesome, thank you!