On 05.06.25 15:51, Lorenzo Stoakes wrote:
The walk_page_range_novma() function is rather confusing - it supports two
modes, one used often, the other used only for debugging.
The first mode is the common case of traversal of kernel page tables, which
is what nearly all callers use this for.
Secondly it provides an unusual debugging interface that allows for the
traversal of page tables in a userland range of memory even for that memory
which is not described by a VMA.
It is far from certain that such page tables should even exist, but perhaps
this is precisely why it is useful as a debugging mechanism.
As a result, this is utilised by ptdump only. Historically, things were
reversed - ptdump was the only user, and other parts of the kernel evolved
to use the kernel page table walking here.
Since we have some complicated and confusing locking rules for the novma
case, it makes sense to separate the two usages into their own functions.
Doing this also provide self-documentation as to the intent of the caller -
are they doing something rather unusual or are they simply doing a standard
kernel page table walk?
We therefore establish two separate functions - walk_page_range_debug() for
this single usage, and walk_kernel_page_table_range() for general kernel
page table walking.
The walk_page_range_debug() function is currently used to traverse both
userland and kernel mappings, so we maintain this and in the case of kernel
mappings being traversed, we have walk_page_range_debug() invoke
walk_kernel_page_table_range() internally.
We additionally make walk_page_range_debug() internal to mm.
Signed-off-by: Lorenzo Stoakes <lorenzo.stoa...@oracle.com>
Acked-by: Mike Rapoport (Microsoft) <r...@kernel.org>
Acked-by: Qi Zheng <zhengqi.a...@bytedance.com>
Reviewed-by: Oscar Salvador <osalva...@suse.de>
Reviewed-by: Suren Baghdasaryan <sur...@google.com>
---
Acked-by: David Hildenbrand <da...@redhat.com>
--
Cheers,
David / dhildenb
