Re: [PATCH v3 20/26] mm/sparse: Register information into meminspect

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Missing meminspect registration for dynamically allocated mem_section leaf arrays in CONFIG_SPARSEMEM_EXTREME.
--

--- Patch [20]: [PATCH v3 20/26] mm/sparse: Register information into meminspect ---
commit 0ac9689f8cff74569f53973955e06ebec50e2b81
Author: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>

mm/sparse: Register information into meminspect

Annotate vital static, dynamic information into meminspect for
debugging:
 - mem_section (static)
 - section (dynamic)

meminspect uses a different API to annotate variables for inspection,
and information about these variables is stored in the inspection table.

> diff --git a/mm/sparse.c b/mm/sparse.c
> index 058ef93003672..9e890fb6c43e1 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
[ ... ]
> @@ -206,6 +208,7 @@ static void __init memblocks_present(void)
>  	size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
>  	align = 1 << (INTERNODE_CACHE_SHIFT);
>  	mem_section = memblock_alloc_or_panic(size, align);
> +	meminspect_lock_register_va(mem_section, size);
>  #endif

[Severity: High]
The commit message mentions annotating "section (dynamic)", but this patch
only registers the root array mem_section. Should the dynamically allocated
leaf arrays in sparse_index_alloc() also be registered?

When CONFIG_SPARSEMEM_EXTREME is enabled, sparse_index_alloc() allocates
these leaf arrays:

mm/sparse.c:sparse_index_alloc() {
    ...
	if (slab_is_available()) {
		section = kzalloc_node(array_size, GFP_KERNEL, nid);
	} else {
		section = memblock_alloc_node(array_size, SMP_CACHE_BYTES,
					      nid);
		if (!section)
			panic("%s: Failed to allocate %lu bytes nid=%d\n",
			      __func__, array_size, nid);
	}
    ...
}

Without registering these leaf arrays, won't debug dumps relying on
meminspect miss the memory section data? This could prevent crash tools
from successfully mapping PFNs to struct page.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260708-meminspect-v3-v3-0-7aa5a0a74d5c@oss.qualcomm.com?part=20