[PATCH v2 0/3] mm: kmemleak: default min_unref_scans to 2 for verbose kernels

When CONFIG_DEBUG_KMEMLEAK_VERBOSE is set, which means the host is in
auto scan mode, set min_unref_scans to 2, avoiding false positives.

CONFIG_DEBUG_KMEMLEAK_VERBOSE depends on CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN,
so a kernel built with it already runs the scan thread periodically and
the user has asked for detailed leak reports.

The confirming second scan comes for free there, so default
min_unref_scans to 2 in that case and keep it at 1 everywhere else.
CONFIG_DEBUG_KMEMLEAK_VERBOSE defaults to n, so nothing changes for
kernels that do not opt in.

The other two patches bring the documentation and the selftest comments
in line with the new conditional default.

PS: A similar patch (v1 of this patchset) is applied to Meta's kernel,
in real production hosts.

Signed-off-by: Breno Leitao <[email protected]>
---
Changes in v2:
- Test only CONFIG_DEBUG_KMEMLEAK_VERBOSE, which already depends on
  CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN; the #if block becomes a plain
  IS_ENABLED() initializer
- Note in the changelog that CONFIG_DEBUG_KMEMLEAK_VERBOSE defaults to n
- New patch: update Documentation/dev-tools/kmemleak.rst, which still
  documented the default as unconditionally 1
- New patch: drop the stale "default" wording from the
  ksft_kmemleak_confirm.sh comments
- Link to v1: https://patch.msgid.link/[email protected]

To: Catalin Marinas <[email protected]>
To: Andrew Morton <[email protected]>
To: Jonathan Corbet <[email protected]>
To: Shuah Khan <[email protected]>
To: David Hildenbrand <[email protected]>
To: Lorenzo Stoakes <[email protected]>
To: "Liam R. Howlett" <[email protected]>
To: Vlastimil Babka <[email protected]>
To: Mike Rapoport <[email protected]>
To: Suren Baghdasaryan <[email protected]>
To: Michal Hocko <[email protected]>
To: Shuah Khan <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]

---
Breno Leitao (3):
      mm: kmemleak: default min_unref_scans to 2 for verbose auto-scan
      Documentation: kmemleak: document the conditional min_unref_scans default
      selftests/mm: kmemleak: drop stale min_unref_scans default from comments

 Documentation/dev-tools/kmemleak.rst                | 12 +++++++-----
 mm/kmemleak.c                                       |  3 ++-
 tools/testing/selftests/mm/ksft_kmemleak_confirm.sh | 10 ++++------
 3 files changed, 13 insertions(+), 12 deletions(-)
---
base-commit: 78bc8af4affb9a732504eb22eeac7d1e50883853
change-id: 20260730-kmemleak_hardened-e80542d1152f

Best regards,
--  
Breno Leitao <[email protected]>