mm: kmemleak: confirm suspected leaks with a second scan

Patch series "mm: kmemleak: reduce transient false positives by confirming
leaks".

This series combines two kmemleak enhancements that were originally
submitted separately but both required rebasing after commit 79c37ae3733e9
("mm/kmemleak: fix checksum computation for per-cpu objects").

The first feature introduces a second scan to confirm suspected leaks:

        https://lore.kernel.org/all/20260709173347.689607-1-catalin.marinas@arm.com/

The second feature adds a module parameter controlling the minimum number
of consecutive unreferenced scans before a leak is reported, as discussed
in:

        https://lore.kernel.org/all/20260626-kmemleak_twice-v1-0-ab28f7cc0971@debian.org/

Changes from v1:
Now that commit 79c37ae3733e9 is upstream, the selftest includes an additional
priming phase scan as requested by Catalin.

Additionally, I've factored out the leak-detection conditional into a helper
function to be more digestible for the reader's eye.

This 4-patch series resolves all outstanding kmemleak issues I've been
tracking.


This patch (of 4):

The kmemleak marking phase is not atomic.  While the object graph is
traversed, the kernel can modify pointers, free objects or allocate new
ones.  If a reference to an object is moved from one location to another,
kmemleak scanning may miss it.  We have explicit annotations like
kmemleak_transient_leak() but identifying and maintaining them is not
trivial.

Given that such transient leaks are short-lived, rather than just
reporting such objects as leaks, do another scan to confirm the suspected
objects.  If no new leaks are found during the first scan, skip the
confirmation one.

Link: https://lore.kernel.org/20260713-catalin_pto-v1-0-5b93b1131089@debian.org
Link: https://lore.kernel.org/20260713-catalin_pto-v1-1-5b93b1131089@debian.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Breno Leitao <leitao@debian.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

0 files changed, 0 insertions, 0 deletions