In this version, I am not touching the kernel code, but, just fixing the selftest, as sashiko reported some issues, and I am addressing them in here.
https://sashiko.dev/#/patchset/20260424-kmemleak_dedup-v2-0-8bea649b2a92%40debian.org NOTE: Additional testing has revealed that lockdep detects a potential lock inversion issue on kmemleak and legacy console. The problem occurs because the function holds &object->lock (a raw spinlock) while invoking printk to report the leak. This printk requires the legacy console_owner lock, which remains in active use despite the ongoing transition to the nbcon framework. Concurrently, console drivers such as hvc (hypervisor virtual console) acquire the console_owner lock and may subsequently free memory. This kfree() operation calls into kmemleak's __delete_object(), which in turn acquires object->lock. Although these code paths hold locks from different object instances, lockdep operates on lock classes rather than individual instances. Since all kmemleak_object->lock instances belong to the same lock class, lockdep identifies this as a circular dependency, even though the actual deadlock scenario cannot occur in practice (?!). This problem was not introduced by this patchset/selftest, but, it is exposing it. I plan to solve it once this patchset is done. Breno Leitao (2): mm/kmemleak: dedupe verbose scan output by allocation backtrace selftests/mm: add kmemleak verbose dedup test mm/kmemleak.c | 102 +++++++++++++++++- .../selftests/mm/test_kmemleak_dedup.sh | 78 ++++++++++++++ 2 files changed, 175 insertions(+), 5 deletions(-) create mode 100755 tools/testing/selftests/mm/test_kmemleak_dedup.sh -- 2.52.0 Signed-off-by: Breno Leitao <[email protected]> --- Changes in v3: - No changes to the first patch (Kernel changes). All changes below are for the selftest. - Pre-cleanup before modprobe — rmmod "$MODULE" 2>/dev/null added before modprobe so a stale load doesn't cause modprobe to be a no-op. - dmesg -C between the two scans — isolates printed count to the second (reporting) scan only. - Link to v2: https://patch.msgid.link/[email protected] Changes in v2: - Drop struct kmemleak_dedup_entry and its kmalloc. (Catalin) - Handle trace_handle == 0 instead of dropping it. - Skip hex dump for coalesced entries (dup_count > 1) — bytes would differ across objects sharing a trace anyway, and it removes the only object->pointer read left in the deferred path. - Counter narrowed from unsigned long count to unsigned int dup_count. - Link to v1: https://patch.msgid.link/[email protected] --- Breno Leitao (2): mm/kmemleak: dedupe verbose scan output by allocation backtrace selftests/mm: add kmemleak verbose dedup test mm/kmemleak.c | 148 ++++++++++++++- tools/testing/selftests/mm/Makefile | 1 + tools/testing/selftests/mm/ksft_kmemleak_dedup.sh | 222 ++++++++++++++++++++++ 3 files changed, 363 insertions(+), 8 deletions(-) --- base-commit: 4cd074ae20bbcc293bbbce9163abe99d68ae6ae0 change-id: 20260420-kmemleak_dedup-bee54ffa65e7 Best regards, -- Breno Leitao <[email protected]>
