Re: [PATCH] riscv: mm: Flush vmemmap TLB after sparse_init()
"David Hildenbrand (Arm)" <[email protected]>
| Newsgroups | org.infradead.lists.linux-riscv,org.kernel.vger.linux-kernel,org.kvack.linux-mm |
|---|---|
| Message-ID | <[email protected]> |
On 8/27/26 09:36, Yaxing Guo wrote:
> Commit 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE
> memory model") moved sparse_init() from RISC-V arch setup code into
> free_area_init(), but left the RISC-V VMEMMAP TLB flush in
> misc_mem_init(). RISC-V now flushes the VMEMMAP range before
> sparse_init() populates the vmemmap page tables.
>
> RISC-V supports caching non-present entries in the TLB. If a hart cached
> a non-present translation for the VMEMMAP range, installing the vmemmap
> page-table entries is not guaranteed to be observed until an sfence.vma
> invalidates the stale entry. The first access to the corresponding
> struct page during memmap initialization can then hit the old non-present
> entry.
>
> Call an arch hook at the end of sparse_init(), after the boot-time
> vmemmap population has completed.
If it's a vmemmap thing, it should go into the vmemmap machinery, not slapped
into sparse.c.
Why can't the proposed vmemmap_populate_finalize() [1] cleanly take care of that?
[1]
https://lore.kernel.org/linux-riscv/20260630-mark-after-vmemmap-populate-v4-1-febbc15da028@iscas.ac.cn/
(independent of that, I really don't enjoy the suggested callback name)
--
Cheers,
David
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