CVE-2026-80729: mm/huge_memory: initialise workingset state before folio split

CVE-2026-80729: mm/huge_memory: initialise workingset state before folio split

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

mm/huge_memory: initialise workingset state before folio split

xas_try_split() adds __GFP_ACCOUNT for page-cache xa_nodes, but
__folio_split() leaves the xa_state's xa_lru unset.  That lets a live,
memcg-charged xa_node exist without being linked into the mapping's
shadow_nodes list_lru; when reclaim later walks the list_lru it trips
VM_WARN_ON(!css_is_dying()).

Use mapping_set_update() to install both the workingset update callback
and the shadow_nodes list_lru on the xa_state.

The Linux kernel CVE team has assigned CVE-2026-80729 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.15 with commit 58729c04cf1092b87aeef0bf0998c9e2e4771133 and fixed in 7.1.9 with commit d858f7c9fc514f1d9d3be7d00b2dd4e2f2383b55
	Issue introduced in 6.15 with commit 58729c04cf1092b87aeef0bf0998c9e2e4771133 and fixed in 7.2 with commit aca1f2d5de17e138bc6c4859126b77e516b82541

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-80729
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	mm/huge_memory.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/d858f7c9fc514f1d9d3be7d00b2dd4e2f2383b55
	https://git.kernel.org/stable/c/aca1f2d5de17e138bc6c4859126b77e516b82541