mm/util: don't read __page_2 for order-1 folios in snapshot_page()
snapshot_page() currently reads __page_2 after checking nr_pages > 1, but
it should only do so when nr_pages > 2.
If an order-1 folio is allocated at the end of a vmemmap section,
__page_2 will not exist and reading it will cause a fault.
During DLPAR memory remove on a 22 TB ppc64le LPAR, snapshot_page() oopsed
on the page isolation path while reading an order-1 folio's __page_2 from
an adjacent absent section (unmapped vmemmap).
Fix this to avoid reading memmap that doesn't exist (e.g., a vmemmap
hole).
Analysis
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Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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No vendor fix or workaround currently provided.
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Fri, 28 Aug 2026 07:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: mm/util: don't read __page_2 for order-1 folios in snapshot_page() snapshot_page() currently reads __page_2 after checking nr_pages > 1, but it should only do so when nr_pages > 2. If an order-1 folio is allocated at the end of a vmemmap section, __page_2 will not exist and reading it will cause a fault. During DLPAR memory remove on a 22 TB ppc64le LPAR, snapshot_page() oopsed on the page isolation path while reading an order-1 folio's __page_2 from an adjacent absent section (unmapped vmemmap). Fix this to avoid reading memmap that doesn't exist (e.g., a vmemmap hole). | |
| Title | mm/util: don't read __page_2 for order-1 folios in snapshot_page() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-28T06:52:51.305Z
Reserved: 2026-08-26T14:34:25.784Z
Link: CVE-2026-80685
Vulnrichment
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NVD
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Redhat
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OpenCVE Enrichment
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No weakness.