[PATCH net v9 0/4] net: netpoll: fix memory leak and add comprehensive selftests

Breno Leitao
2025-11-06T15:56:57Z

Fix a memory leak in netpoll and introduce netconsole selftests that
expose the issue when running with kmemleak detection enabled.

This patchset includes a selftest for netpoll with multiple concurrent
users (netconsole + bonding), which simulates the scenario from test[1]
that originally demonstrated the issue allegedly fixed by commit
efa95b01da18 ("netpoll: fix use after free") - a commit that is now
being reverted.

Sending this to "net" branch because this is a fix, and the selftest
might help with the backports validation.

Link: https://lore.kernel.org/lkml/96b940137a50e5c387687bb4f57de8b0435a653f.1404857349.git.decot@googlers.com/ [1]

Signed-off-by: Breno Leitao <leitao@debian.org>
---
Changes in v9:
- Reordered the config entries in tools/testing/selftests/drivers/net/bonding/config (NIPA)
- Link to v8: https://lore.kernel.org/r/20251104-netconsole_torture-v8-0-5288440e2fa0@debian.org

Changes in v8:
- Sending it again, now that commit 1a8fed52f7be1 ("netdevsim: set the
carrier when the device goes up") has landed in net
- Created one namespace for TX and one for RX (Paolo)
- Used additional helpers to create and delete netdevsim (Paolo)
- Link to v7: https://lore.kernel.org/r/20251003-netconsole_torture-v7-0-aa92fcce62a9@debian.org

Changes in v7:
- Rebased on top of `net`
- Link to v6: https://lore.kernel.org/r/20251002-netconsole_torture-v6-0-543bf52f6b46@debian.org

Changes in v6:
- Expand the tests even more and some small fixups
- Moved the test to bonding selftests
- Link to v5: https://lore.kernel.org/r/20250918-netconsole_torture-v5-0-77e25e0a4eb6@debian.org

Changes in v5:
- Set CONFIG_BONDING=m in selftests/drivers/net/config.
- Link to v4: https://lore.kernel.org/r/20250917-netconsole_torture-v4-0-0a5b3b8f81ce@debian.org

Changes in v4:
- Added an additional selftest to test multiple netpoll users in
parallel
- Link to v3: https://lore.kernel.org/r/20250905-netconsole_torture-v3-0-875c7febd316@debian.org

Changes in v3:
- This patchset is a merge of the fix and the selftest together as
recommended by Jakub.

Changes in v2:
- Reuse the netconsole creation from lib_netcons.sh. Thus, refactoring
the create_dynamic_target() (Jakub)
- Move the "wait" to after all the messages has been sent.
- Link to v1: https://lore.kernel.org/r/20250902-netconsole_torture-v1-1-03c6066598e9@debian.org

---
Breno Leitao (4):
net: netpoll: fix incorrect refcount handling causing incorrect cleanup
selftest: netcons: refactor target creation
selftest: netcons: create a torture test
selftest: netcons: add test for netconsole over bonded interfaces

net/core/netpoll.c | 7 +-
tools/testing/selftests/drivers/net/Makefile | 1 +
.../testing/selftests/drivers/net/bonding/Makefile | 2 +
tools/testing/selftests/drivers/net/bonding/config | 4 +
.../drivers/net/bonding/netcons_over_bonding.sh | 361 +++++++++++++++++++++
.../selftests/drivers/net/lib/sh/lib_netcons.sh | 82 ++++-
.../selftests/drivers/net/netcons_torture.sh | 130 ++++++++
7 files changed, 569 insertions(+), 18 deletions(-)
---
base-commit: 7d1988a943850c584e8e2e4bcc7a3b5275024072
change-id: 20250902-netconsole_torture-8fc23f0aca99

Best regards,
--
Breno Leitao <leitao@debian.org>