CVE-2026-74644: mm/damon/ops-common: putback folios on invalid migrate nid

From: Greg Kroah-Hartman <[email protected]>

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

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

mm/damon/ops-common: putback folios on invalid migrate nid

damon_pa_migrate() and damos_va_migrate() isolate folios into a local list
and then call damon_migrate_pages().  When target_nid is invalid
(including the scheme default NUMA_NO_NODE / -1), damon_migrate_pages()
returns early without putting the folios back to the LRU.

Callers then discard the list head while those folios remain isolated with
an extra reference taken by folio_isolate_lru().  The pages stay off the
LRU for as long as the mapping exists (anon active+inactive counts drop
while RSS does not), and the leftover references can pin the pages after
the mapping is gone.

Put the folios back on the invalid-nid path so ignored migration requests
still return them to the LRU.

The Linux kernel CVE team has assigned CVE-2026-74644 to this issue.


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

	Issue introduced in 6.17 with commit 7e6c3130690a01076efdf45aa02ba5d5c16849a0 and fixed in 6.18.45 with commit 460181e4bb47a57776c64f0832c2096de8878cb3
	Issue introduced in 6.17 with commit 7e6c3130690a01076efdf45aa02ba5d5c16849a0 and fixed in 7.1.9 with commit cfef454862b7d2776e0955b873dd59af6b47cfcb
	Issue introduced in 6.17 with commit 7e6c3130690a01076efdf45aa02ba5d5c16849a0 and fixed in 7.2 with commit 5deb65c34e682e7c5f5df417a70e223e8fcc5f5a
	Issue introduced in 6.12.44 with commit 7c303fa1f311aadc17fa82b7bbf776412adf45de
	Issue introduced in 6.16.4 with commit 9d0c2d15aff96746f99a7c97221bb8ce5b62db19

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-2026-74644
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/damon/ops-common.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/460181e4bb47a57776c64f0832c2096de8878cb3
	https://git.kernel.org/stable/c/cfef454862b7d2776e0955b873dd59af6b47cfcb
	https://git.kernel.org/stable/c/5deb65c34e682e7c5f5df417a70e223e8fcc5f5a