November 2025 - Linux-kselftest-mirror

[PATCH 00/21] vfio/pci: Base support to preserve a VFIO device file across Live Update

by David Matlack

This series adds the base support to preserve a VFIO device file across a Live Update. "Base support" means that this allows userspace to safetly preserve a VFIO device file with LIVEUPDATE_SESSION_PRESERVE_FD and retrieve a preserved VFIO device file with LIVEUPDATE_SESSION_RETRIEVE_FD, but the device itself is not preserved in a fully running state across Live Update. This series unblocks 2 parallel but related streams of work: - iommufd preservation across Live Update. This work spans iommufd, the IOMMU subsystem, and IOMMU drivers [1] - Preservation of VFIO device state across Live Update (config space, BAR addresses, power state, SR-IOV state, etc.). This work spans both VFIO and the core PCI subsystem. While we need all of the above to fully preserve a VFIO device across a Live Update without disrupting the workload on the device, this series aims to be functional and safe enough to merge as the first incremental step toward that goal. Areas for Discussion -------------------- BDF Stability across Live Update The PCI support for tracking preserved devices across a Live Update to prevent auto-probing relies on PCI segment numbers and BDFs remaining stable. For now I have disallowed VFs, as the BDFs assigned to VFs can vary depending on how the kernel chooses to allocate bus numbers. For non-VFs I am wondering if there is any more needed to ensure BDF stability across Live Update. While we would like to support many different systems and configurations in due time (including preserving VFs), I'd like to keep this first serses constrained to simple use-cases. FLB Locking I don't see a way to properly synchronize pci_flb_finish() with pci_liveupdate_incoming_is_preserved() since the incoming FLB mutex is dropped by liveupdate_flb_get_incoming() when it returns the pointer to the object, and taking pci_flb_incoming_lock in pci_flb_finish() could result in a deadlock due to reversing the lock ordering. FLB Retrieving The first patch of this series includes a fix to prevent an FLB from being retrieved again it is finished. I am wondering if this is the right approach or if subsystems are expected to stop calling liveupdate_flb_get_incoming() after an FLB is finished. Testing ------- The patches at the end of this series provide comprehensive selftests for the new code added by this series. The selftests have been validated in both a VM environment using a virtio-net PCIe device, and in a baremetal environment on an Intel EMR server with an Intel DSA device. Here is an example of how to run the new selftests: vfio_pci_liveupdate_uapi_test: $ tools/testing/selftests/vfio/scripts/setup.sh 0000:00:04.0 $ tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test 0000:00:04.0 $ tools/testing/selftests/vfio/scripts/cleanup.sh vfio_pci_liveupdate_kexec_test: $ tools/testing/selftests/vfio/scripts/setup.sh 0000:00:04.0 $ tools/testing/selftests/vfio/vfio_pci_liveupdate_kexec_test --stage 1 0000:00:04.0 $ kexec [...] # NOTE: distro-dependent $ tools/testing/selftests/vfio/scripts/setup.sh 0000:00:04.0 $ tools/testing/selftests/vfio/vfio_pci_liveupdate_kexec_test --stage 2 0000:00:04.0 $ tools/testing/selftests/vfio/scripts/cleanup.sh Dependencies ------------ This series was constructed on top of several in-flight series and on top of mm-nonmm-unstable [2]. +-- This series | +-- [PATCH v2 00/18] vfio: selftests: Support for multi-device tests | https://lore.kernel.org/kvm/20251112192232.442761-1-dmatlack@google.com/ | +-- [PATCH v3 0/4] vfio: selftests: update DMA mapping tests to use queried IOVA ranges | https://lore.kernel.org/kvm/20251111-iova-ranges-v3-0-7960244642c5@fb.com/ | +-- [PATCH v8 0/2] Live Update: File-Lifecycle-Bound (FLB) State | https://lore.kernel.org/linux-mm/20251125225006.3722394-1-pasha.tatashin@so… | +-- [PATCH v8 00/18] Live Update Orchestrator | https://lore.kernel.org/linux-mm/20251125165850.3389713-1-pasha.tatashin@so… | To simplify checking out the code, this series can be found on GitHub: https://github.com/dmatlack/linux/tree/liveupdate/vfio/cdev/v1 Changelog --------- v1: - Rebase series on top of LUOv8 and VFIO selftests improvements - Drop commits to preserve config space fields across Live Update. These changes require changes to the PCI layer. For exmaple, preserving rbars could lead to an inconsistent device state until device BARs addresses are preserved across Live Update. - Drop commits to preserve Bus Master Enable on the device. There's no reason to preserve this until iommufd preservation is fully working. Furthermore, preserving Bus Master Enable could lead to memory corruption when the device if the device is bound to the default identity-map domain after Live Update. - Drop commits to preserve saved PCI state. This work is not needed until we are ready to preserve the device's config space, and requires more thought to make the PCI state data layout ABI-friendly. - Add support to skip auto-probing devices that are preserved by VFIO to avoid them getting bound to a different driver by the next kernel. - Restrict device preservation further (no VFs, no intel-graphics). - Various refactoring and small edits to improve readability and eliminate code duplication. rfc: https://lore.kernel.org/kvm/20251018000713.677779-1-vipinsh@google.com/ Cc: Saeed Mahameed <saeedm(a)nvidia.com> Cc: Adithya Jayachandran <ajayachandra(a)nvidia.com> Cc: Jason Gunthorpe <jgg(a)nvidia.com> Cc: Parav Pandit <parav(a)nvidia.com> Cc: Leon Romanovsky <leonro(a)nvidia.com> Cc: William Tu <witu(a)nvidia.com> Cc: Jacob Pan <jacob.pan(a)linux.microsoft.com> Cc: Lukas Wunner <lukas(a)wunner.de> Cc: Pasha Tatashin <pasha.tatashin(a)soleen.com> Cc: Mike Rapoport <rppt(a)kernel.org> Cc: Pratyush Yadav <pratyush(a)kernel.org> Cc: Samiullah Khawaja <skhawaja(a)google.com> Cc: Chris Li <chrisl(a)kernel.org> Cc: Josh Hilke <jrhilke(a)google.com> Cc: David Rientjes <rientjes(a)google.com> [1] https://lore.kernel.org/linux-iommu/20250928190624.3735830-1-skhawaja@googl… [2] https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/log/?h=mm-nonmm… David Matlack (12): liveupdate: luo_flb: Prevent retrieve() after finish() PCI: Add API to track PCI devices preserved across Live Update PCI: Require driver_override for incoming Live Update preserved devices vfio/pci: Notify PCI subsystem about devices preserved across Live Update vfio: Enforce preserved devices are retrieved via LIVEUPDATE_SESSION_RETRIEVE_FD vfio/pci: Store Live Update state in struct vfio_pci_core_device vfio: selftests: Add Makefile support for TEST_GEN_PROGS_EXTENDED vfio: selftests: Add vfio_pci_liveupdate_uapi_test vfio: selftests: Expose iommu_modes to tests vfio: selftests: Expose low-level helper routines for setting up struct vfio_pci_device vfio: selftests: Verify that opening VFIO device fails during Live Update vfio: selftests: Add continuous DMA to vfio_pci_liveupdate_kexec_test Vipin Sharma (9): vfio/pci: Register a file handler with Live Update Orchestrator vfio/pci: Preserve vfio-pci device files across Live Update vfio/pci: Retrieve preserved device files after Live Update vfio/pci: Skip reset of preserved device after Live Update selftests/liveupdate: Move luo_test_utils.* into a reusable library selftests/liveupdate: Add helpers to preserve/retrieve FDs vfio: selftests: Build liveupdate library in VFIO selftests vfio: selftests: Initialize vfio_pci_device using a VFIO cdev FD vfio: selftests: Add vfio_pci_liveupdate_kexec_test MAINTAINERS | 1 + drivers/pci/Makefile | 1 + drivers/pci/liveupdate.c | 248 ++++++++++++++++ drivers/pci/pci-driver.c | 12 +- drivers/vfio/device_cdev.c | 25 +- drivers/vfio/group.c | 9 + drivers/vfio/pci/Makefile | 1 + drivers/vfio/pci/vfio_pci.c | 11 +- drivers/vfio/pci/vfio_pci_core.c | 23 +- drivers/vfio/pci/vfio_pci_liveupdate.c | 278 ++++++++++++++++++ drivers/vfio/pci/vfio_pci_priv.h | 16 + drivers/vfio/vfio.h | 13 - drivers/vfio/vfio_main.c | 22 +- include/linux/kho/abi/pci.h | 53 ++++ include/linux/kho/abi/vfio_pci.h | 45 +++ include/linux/liveupdate.h | 3 + include/linux/pci.h | 38 +++ include/linux/vfio.h | 51 ++++ include/linux/vfio_pci_core.h | 7 + kernel/liveupdate/luo_flb.c | 4 + tools/testing/selftests/liveupdate/.gitignore | 1 + tools/testing/selftests/liveupdate/Makefile | 14 +- .../include/libliveupdate.h} | 11 +- .../selftests/liveupdate/lib/libliveupdate.mk | 20 ++ .../{luo_test_utils.c => lib/liveupdate.c} | 43 ++- .../selftests/liveupdate/luo_kexec_simple.c | 2 +- .../selftests/liveupdate/luo_multi_session.c | 2 +- tools/testing/selftests/vfio/Makefile | 23 +- .../vfio/lib/include/libvfio/iommu.h | 2 + .../lib/include/libvfio/vfio_pci_device.h | 8 + tools/testing/selftests/vfio/lib/iommu.c | 4 +- .../selftests/vfio/lib/vfio_pci_device.c | 60 +++- .../vfio/vfio_pci_liveupdate_kexec_test.c | 255 ++++++++++++++++ .../vfio/vfio_pci_liveupdate_uapi_test.c | 93 ++++++ 34 files changed, 1313 insertions(+), 86 deletions(-) create mode 100644 drivers/pci/liveupdate.c create mode 100644 drivers/vfio/pci/vfio_pci_liveupdate.c create mode 100644 include/linux/kho/abi/pci.h create mode 100644 include/linux/kho/abi/vfio_pci.h rename tools/testing/selftests/liveupdate/{luo_test_utils.h => lib/include/libliveupdate.h} (80%) create mode 100644 tools/testing/selftests/liveupdate/lib/libliveupdate.mk rename tools/testing/selftests/liveupdate/{luo_test_utils.c => lib/liveupdate.c} (89%) create mode 100644 tools/testing/selftests/vfio/vfio_pci_liveupdate_kexec_test.c create mode 100644 tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test.c -- 2.52.0.487.g5c8c507ade-goog

2 hours, 43 minutes

6
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[PATCH v4 0/3] selftests: cgroup: Enhance robustness with polling helpers

by Guopeng Zhang

Hi all, This patch series introduces improvements to the cgroup selftests by adding helper functions to better handle asynchronous updates in cgroup statistics. These changes are especially useful for managing cgroup stats like memory.stat and cgroup.stat, which can be affected by delays (e.g., RCPU callbacks and asynchronous rstat flushing). v4: - Patch 1/3: Adds the `cg_read_key_long_poll()` helper to poll cgroup keys with retries and configurable intervals. - Patch 2/3: Updates `test_memcg_sock()` to use `cg_read_key_long_poll()` for handling delayed "sock" counter updates in memory.stat. - Patch 3/3: Replaces `sleep` and retry logic in `test_kmem_dead_cgroups()` with `cg_read_key_long_poll()` for waiting on `nr_dying_descendants`. v3: - Move `MEMCG_SOCKSTAT_WAIT_*` defines after the `#include` block as suggested. v2: - Clarify the rationale for the 3s timeout and mention the periodic rstat flush interval (FLUSH_TIME = 2*HZ) in the comment. - Replace hardcoded retry count and wait interval with macros to avoid magic numbers and make the timeout calculation explicit. Thanks to Michal Koutný for the suggestion to introduce the polling helper, and to Lance Yang for the review. Guopeng Zhang (3): selftests: cgroup: Add cg_read_key_long_poll() to poll a cgroup key with retries selftests: cgroup: make test_memcg_sock robust against delayed sock stats selftests: cgroup: Replace sleep with cg_read_key_long_poll() for waiting on nr_dying_descendants .../selftests/cgroup/lib/cgroup_util.c | 21 +++++++++++++ .../cgroup/lib/include/cgroup_util.h | 5 +++ tools/testing/selftests/cgroup/test_kmem.c | 31 ++++++++----------- .../selftests/cgroup/test_memcontrol.c | 20 +++++++++++- 4 files changed, 58 insertions(+), 19 deletions(-) -- 2.25.1

3 hours, 17 minutes

3
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[PATCH net-next V3 0/6] selftests: drv-net: Fix issues in devlink_rate_tc_bw.py

by Carolina Jubran

Hi, This series fixes issues in the devlink_rate_tc_bw.py selftest and introduces a new Iperf3Runner that helps with measurement handling. Thanks, Carolina V3: - Replace generic Exception with specific exception types in load.py. V2: - Insert the test in the correct sorted position. Carolina Jubran (6): selftests: drv-net: Add devlink_rate_tc_bw.py to TEST_PROGS selftests: drv-net: introduce Iperf3Runner for measurement use cases selftests: drv-net: Use Iperf3Runner in devlink_rate_tc_bw.py selftests: drv-net: Set shell=True for sysfs writes in devlink_rate_tc_bw.py selftests: drv-net: Fix and clarify TC bandwidth split in devlink_rate_tc_bw.py selftests: drv-net: Fix tolerance calculation in devlink_rate_tc_bw.py .../testing/selftests/drivers/net/hw/Makefile | 1 + .../drivers/net/hw/devlink_rate_tc_bw.py | 174 ++++++++---------- .../drivers/net/hw/lib/py/__init__.py | 5 +- .../selftests/drivers/net/lib/py/__init__.py | 5 +- .../selftests/drivers/net/lib/py/load.py | 84 ++++++++- 5 files changed, 157 insertions(+), 112 deletions(-) -- 2.38.1

7 hours, 43 minutes

2
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[PATCH net-next 0/4] (no cover subject)

by Breno Leitao

This patch series introduces a new configfs attribute that enables sending messages directly through netconsole without going through the kernel's logging infrastructure. This feature allows users to send custom messages, alerts, or status updates directly to netconsole receivers by writing to /sys/kernel/config/netconsole/<target>/send_msg, without poluting kernel buffers, and sending msgs to the serial, which could be slow. At Meta this is currently used in two cases right now (through printk by now): a) When a new workload enters or leave the machine. b) From time to time, as a "ping" to make sure the netconsole/machine is alive. The implementation reuses the existing message transmission functions (send_msg_udp() and send_ext_msg_udp()) to handle both basic and extended message formats. Regarding code organization, this version uses forward declarations for send_msg_udp() and send_ext_msg_udp() functions rather than relocating them within the file. While forward declarations do add a small amount of redundancy, they avoid the larger churn that would result from moving entire function definitions. --- Breno Leitao (4): netconsole: extract message fragmentation into send_msg_udp() netconsole: Add configfs attribute for direct message sending selftests/netconsole: Switch to configfs send_msg interface Documentation: netconsole: Document send_msg configfs attribute Documentation/networking/netconsole.rst | 40 +++++++++++++++ drivers/net/netconsole.c | 59 ++++++++++++++++++---- .../selftests/drivers/net/netcons_sysdata.sh | 2 +- 3 files changed, 91 insertions(+), 10 deletions(-) --- base-commit: ab084f0b8d6d2ee4b1c6a28f39a2a7430bdfa7f0 change-id: 20251127-netconsole_send_msg-89813956dc23 Best regards, -- Breno Leitao <leitao(a)debian.org>

8 hours, 27 minutes

3
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[PATCH] KVM: selftests: Fix core dump in rseq_test

by Gavin Shan

In commit 0297cdc12a87 ("KVM: selftests: Add option to rseq test to override /dev/cpu_dma_latency"), a 'break' is missed before the option 'l' in the argument parsing loop, which leads to an unexpected core dump in atoi_paranoid(). It tries to get the latency from non-existent argument. host$ ./rseq_test -u Random seed: 0x6b8b4567 Segmentation fault (core dumped) Add a 'break' before the option 'l' in the argument parsing loop to avoid the unexpected core dump. Fixes: 0297cdc12a87 ("KVM: selftests: Add option to rseq test to override /dev/cpu_dma_latency") Cc: stable(a)vger.kernel.org # v6.15+ Signed-off-by: Gavin Shan <gshan(a)redhat.com> --- tools/testing/selftests/kvm/rseq_test.c | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/testing/selftests/kvm/rseq_test.c b/tools/testing/selftests/kvm/rseq_test.c index 1375fca80bcdb..f80ad6b47d16b 100644 --- a/tools/testing/selftests/kvm/rseq_test.c +++ b/tools/testing/selftests/kvm/rseq_test.c @@ -215,6 +215,7 @@ int main(int argc, char *argv[]) switch (opt) { case 'u': skip_sanity_check = true; + break; case 'l': latency = atoi_paranoid(optarg); break; -- 2.51.1

9 hours, 47 minutes

1
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[PATCH net-next v8 0/5] netconsole: support automatic target recovery

by Andre Carvalho

This patchset introduces target resume capability to netconsole allowing it to recover targets when underlying low-level interface comes back online. The patchset starts by refactoring netconsole state representation in order to allow representing deactivated targets (targets that are disabled due to interfaces unregister). It then modifies netconsole to handle NETDEV_REGISTER events for such targets, setups netpoll and forces the device UP. Targets are matched with incoming interfaces depending on how they were bound in netconsole (by mac or interface name). For these reasons, we also attempt resuming on NETDEV_CHANGENAME. The patchset includes a selftest that validates netconsole target state transitions and that target is functional after resumed. Signed-off-by: Andre Carvalho <asantostc(a)gmail.com> --- Changes in v8: - Handle NETDEV_REGISTER/CHANGENAME instead of NETDEV_UP (and force the device UP), to increase the chances of succesfully resuming a target. This requires using a workqueue instead of inline in the event notifier as we can't UP the device otherwise. - Link to v7: https://lore.kernel.org/r/20251126-netcons-retrigger-v7-0-1d86dba83b1c@gmai… Changes in v7: - selftest: use ${EXIT_STATUS} instead of ${ksft_pass} to avoid shellcheck warning - Link to v6: https://lore.kernel.org/r/20251121-netcons-retrigger-v6-0-9c03f5a2bd6f@gmai… Changes in v6: - Rebase on top of net-next to resolve conflicts, no functional changes. - Link to v5: https://lore.kernel.org/r/20251119-netcons-retrigger-v5-0-2c7dda6055d6@gmai… Changes in v5: - patch 3: Set (de)enslaved target as DISABLED instead of DEACTIVATED to prevent resuming it. - selftest: Fix test cleanup by moving trap line to outside of loop and remove unneeded 'local' keyword - Rename maybe_resume_target to resume_target, add netconsole_ prefix to process_resumable_targets. - Hold device reference before calling __netpoll_setup. - Link to v4: https://lore.kernel.org/r/20251116-netcons-retrigger-v4-0-5290b5f140c2@gmai… Changes in v4: - Simplify selftest cleanup, removing trap setup in loop. - Drop netpoll helper (__setup_netpoll_hold) and manage reference inside netconsole. - Move resume_list processing logic to separate function. - Link to v3: https://lore.kernel.org/r/20251109-netcons-retrigger-v3-0-1654c280bbe6@gmai… Changes in v3: - Resume by mac or interface name depending on how target was created. - Attempt to resume target without holding target list lock, by moving the target to a temporary list. This is required as netpoll may attempt to allocate memory. - Link to v2: https://lore.kernel.org/r/20250921-netcons-retrigger-v2-0-a0e84006237f@gmai… Changes in v2: - Attempt to resume target in the same thread, instead of using workqueue . - Add wrapper around __netpoll_setup (patch 4). - Renamed resume_target to maybe_resume_target and moved conditionals to inside its implementation, keeping code more clear. - Verify that device addr matches target mac address when target was setup using mac. - Update selftest to cover targets bound by mac and interface name. - Fix typo in selftest comment and sort tests alphabetically in Makefile. - Link to v1: https://lore.kernel.org/r/20250909-netcons-retrigger-v1-0-3aea904926cf@gmai… --- Andre Carvalho (3): netconsole: convert 'enabled' flag to enum for clearer state management netconsole: resume previously deactivated target selftests: netconsole: validate target resume Breno Leitao (2): netconsole: add target_state enum netconsole: add STATE_DEACTIVATED to track targets disabled by low level drivers/net/netconsole.c | 171 +++++++++++++++++---- tools/testing/selftests/drivers/net/Makefile | 1 + .../selftests/drivers/net/lib/sh/lib_netcons.sh | 35 ++++- .../selftests/drivers/net/netcons_resume.sh | 97 ++++++++++++ 4 files changed, 270 insertions(+), 34 deletions(-) --- base-commit: ed01d2069e8b40eb283050b7119c25a67542a585 change-id: 20250816-netcons-retrigger-a4f547bfc867 Best regards, -- Andre Carvalho <asantostc(a)gmail.com>

10 hours, 57 minutes

3
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[PATCH net-next 1/2] selftests: drv-net: gro: improve feature config

by Jakub Kicinski

We'll need to do a lot more feature handling to test HW-GRO and LRO. Clean up the feature handling for SW GRO a bit to let the next commit focus on the new test cases, only. Make sure HW GRO-like features are not enabled for the SW tests. Be more careful about changing features as "nothing changed" situations may result in non-zero error code from ethtool. Don't disable TSO on the local interface (receiver) when running over netdevsim, we just want GSO to break up the segments on the sender. Signed-off-by: Jakub Kicinski <kuba(a)kernel.org> --- CC: shuah(a)kernel.org CC: linux-kselftest(a)vger.kernel.org --- tools/testing/selftests/drivers/net/gro.py | 38 ++++++++++++++++++++-- 1 file changed, 35 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/drivers/net/gro.py b/tools/testing/selftests/drivers/net/gro.py index ba83713bf7b5..6d633bdc7e67 100755 --- a/tools/testing/selftests/drivers/net/gro.py +++ b/tools/testing/selftests/drivers/net/gro.py @@ -20,7 +20,7 @@ coalescing behavior. import os from lib.py import ksft_run, ksft_exit, ksft_pr from lib.py import NetDrvEpEnv, KsftXfailEx -from lib.py import cmd, defer, bkg, ip +from lib.py import cmd, defer, bkg, ethtool, ip from lib.py import ksft_variants @@ -70,6 +70,27 @@ from lib.py import ksft_variants defer(ip, f"link set dev {dev['ifname']} mtu {dev['mtu']}", host=host) +def _set_ethtool_feat(dev, current, feats, host=None): + s2n = {True: "on", False: "off"} + + new = ["-K", dev] + old = ["-K", dev] + no_change = True + for name, state in feats.items(): + new += [name, s2n[state]] + old += [name, s2n[not state]] + + if current[name]["active"] != state: + no_change = False + if current[name]["fixed"]: + raise KsftXfailEx(f"Device does not support {name}") + if no_change: + return + + ethtool(" ".join(new), host=host) + defer(ethtool, " ".join(old), host=host) + + def _setup(cfg, test_name): """ Setup hardware loopback mode for GRO testing. """ @@ -77,6 +98,11 @@ from lib.py import ksft_variants cfg.bin_local = cfg.test_dir / "gro" cfg.bin_remote = cfg.remote.deploy(cfg.bin_local) + if not hasattr(cfg, "feat"): + cfg.feat = ethtool(f"-k {cfg.ifname}", json=True)[0] + cfg.remote_feat = ethtool(f"-k {cfg.remote_ifname}", + host=cfg.remote, json=True)[0] + # "large" test needs at least 4k MTU if test_name == "large": _set_mtu_restore(cfg.dev, 4096, None) @@ -88,15 +114,21 @@ from lib.py import ksft_variants _write_defer_restore(cfg, flush_path, "200000", defer_undo=True) _write_defer_restore(cfg, irq_path, "10", defer_undo=True) + _set_ethtool_feat(cfg.ifname, cfg.feat, + {"generic-receive-offload": True, + "rx-gro-hw": False, + "large-receive-offload": False}) + try: # Disable TSO for local tests cfg.require_nsim() # will raise KsftXfailEx if not running on nsim - cmd(f"ethtool -K {cfg.ifname} gro on tso off") - cmd(f"ethtool -K {cfg.remote_ifname} gro on tso off", host=cfg.remote) + _set_ethtool_feat(cfg.remote_ifname, cfg.remote_feat, {"tso": False}, + host=cfg.remote) except KsftXfailEx: pass + def _gro_variants(): """Generator that yields all combinations of protocol and test types.""" -- 2.51.1

11 hours, 12 minutes

2
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[PATCH v12] exec: Fix dead-lock in de_thread with ptrace_attach

by Bernd Edlinger

This introduces signal->exec_bprm, which is used to fix the case when at least one of the sibling threads is traced, and therefore the trace process may dead-lock in ptrace_attach, but de_thread will need to wait for the tracer to continue execution. The solution is to detect this situation and allow ptrace_attach to continue by temporarily releasing the cred_guard_mutex, while de_thread() is still waiting for traced zombies to be eventually released by the tracer. In the case of the thread group leader we only have to wait for the thread to become a zombie, which may also need co-operation from the tracer due to PTRACE_O_TRACEEXIT. When a tracer wants to ptrace_attach a task that already is in execve, we simply retry the ptrace_may_access check while temporarily installing the new credentials and dumpability which are about to be used after execve completes. If the ptrace_attach happens on a thread that is a sibling-thread of the thread doing execve, it is sufficient to check against the old credentials, as this thread will be waited for, before the new credentials are installed. Other threads die quickly since the cred_guard_mutex is released, but a deadly signal is already pending. In case the mutex_lock_killable misses the signal, the non-zero current->signal->exec_bprm makes sure they release the mutex immediately and return with -ERESTARTNOINTR. This means there is no API change, unlike the previous version of this patch which was discussed here: https://lore.kernel.org/lkml/b6537ae6-31b1-5c50-f32b-8b8332ace882@hotmail.d… See tools/testing/selftests/ptrace/vmaccess.c for a test case that gets fixed by this change. Note that since the test case was originally designed to test the ptrace_attach returning an error in this situation, the test expectation needed to be adjusted, to allow the API to succeed at the first attempt. Signed-off-by: Bernd Edlinger <bernd.edlinger(a)hotmail.de> --- fs/exec.c | 69 ++++++++++++++++------- fs/proc/base.c | 6 ++ include/linux/cred.h | 1 + include/linux/sched/signal.h | 18 ++++++ kernel/cred.c | 28 +++++++-- kernel/ptrace.c | 32 +++++++++++ kernel/seccomp.c | 12 +++- tools/testing/selftests/ptrace/vmaccess.c | 23 +++++--- 8 files changed, 155 insertions(+), 34 deletions(-) v10: Changes to previous version, make the PTRACE_ATTACH retun -EAGAIN, instead of execve return -ERESTARTSYS. Added some lessions learned to the description. v11: Check old and new credentials in PTRACE_ATTACH again without changing the API. Note: I got actually one response from an automatic checker to the v11 patch, https://lore.kernel.org/lkml/202107121344.wu68hEPF-lkp@intel.com/ which is complaining about: >> kernel/ptrace.c:425:26: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct cred const *old_cred @@ got struct cred const [noderef] __rcu *real_cred @@ 417 struct linux_binprm *bprm = task->signal->exec_bprm; 418 const struct cred *old_cred; 419 struct mm_struct *old_mm; 420 421 retval = down_write_killable(&task->signal->exec_update_lock); 422 if (retval) 423 goto unlock_creds; 424 task_lock(task); > 425 old_cred = task->real_cred; v12: Essentially identical to v11. - Fixed a minor merge conflict in linux v5.17, and fixed the above mentioned nit by adding __rcu to the declaration. - re-tested the patch with all linux versions from v5.11 to v6.6 v10 was an alternative approach which did imply an API change. But I would prefer to avoid such an API change. The difficult part is getting the right dumpability flags assigned before de_thread starts, hope you like this version. If not, the v10 is of course also acceptable. Thanks Bernd. diff --git a/fs/exec.c b/fs/exec.c index 2f2b0acec4f0..902d3b230485 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1041,11 +1041,13 @@ static int exec_mmap(struct mm_struct *mm) return 0; } -static int de_thread(struct task_struct *tsk) +static int de_thread(struct task_struct *tsk, struct linux_binprm *bprm) { struct signal_struct *sig = tsk->signal; struct sighand_struct *oldsighand = tsk->sighand; spinlock_t *lock = &oldsighand->siglock; + struct task_struct *t = tsk; + bool unsafe_execve_in_progress = false; if (thread_group_empty(tsk)) goto no_thread_group; @@ -1068,6 +1070,19 @@ static int de_thread(struct task_struct *tsk) if (!thread_group_leader(tsk)) sig->notify_count--; + while_each_thread(tsk, t) { + if (unlikely(t->ptrace) + && (t != tsk->group_leader || !t->exit_state)) + unsafe_execve_in_progress = true; + } + + if (unlikely(unsafe_execve_in_progress)) { + spin_unlock_irq(lock); + sig->exec_bprm = bprm; + mutex_unlock(&sig->cred_guard_mutex); + spin_lock_irq(lock); + } + while (sig->notify_count) { __set_current_state(TASK_KILLABLE); spin_unlock_irq(lock); @@ -1158,6 +1173,11 @@ static int de_thread(struct task_struct *tsk) release_task(leader); } + if (unlikely(unsafe_execve_in_progress)) { + mutex_lock(&sig->cred_guard_mutex); + sig->exec_bprm = NULL; + } + sig->group_exec_task = NULL; sig->notify_count = 0; @@ -1169,6 +1189,11 @@ static int de_thread(struct task_struct *tsk) return 0; killed: + if (unlikely(unsafe_execve_in_progress)) { + mutex_lock(&sig->cred_guard_mutex); + sig->exec_bprm = NULL; + } + /* protects against exit_notify() and __exit_signal() */ read_lock(&tasklist_lock); sig->group_exec_task = NULL; @@ -1253,6 +1278,24 @@ int begin_new_exec(struct linux_binprm * bprm) if (retval) return retval; + /* If the binary is not readable then enforce mm->dumpable=0 */ + would_dump(bprm, bprm->file); + if (bprm->have_execfd) + would_dump(bprm, bprm->executable); + + /* + * Figure out dumpability. Note that this checking only of current + * is wrong, but userspace depends on it. This should be testing + * bprm->secureexec instead. + */ + if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP || + is_dumpability_changed(current_cred(), bprm->cred) || + !(uid_eq(current_euid(), current_uid()) && + gid_eq(current_egid(), current_gid()))) + set_dumpable(bprm->mm, suid_dumpable); + else + set_dumpable(bprm->mm, SUID_DUMP_USER); + /* * Ensure all future errors are fatal. */ @@ -1261,7 +1304,7 @@ int begin_new_exec(struct linux_binprm * bprm) /* * Make this the only thread in the thread group. */ - retval = de_thread(me); + retval = de_thread(me, bprm); if (retval) goto out; @@ -1284,11 +1327,6 @@ int begin_new_exec(struct linux_binprm * bprm) if (retval) goto out; - /* If the binary is not readable then enforce mm->dumpable=0 */ - would_dump(bprm, bprm->file); - if (bprm->have_execfd) - would_dump(bprm, bprm->executable); - /* * Release all of the old mmap stuff */ @@ -1350,18 +1388,6 @@ int begin_new_exec(struct linux_binprm * bprm) me->sas_ss_sp = me->sas_ss_size = 0; - /* - * Figure out dumpability. Note that this checking only of current - * is wrong, but userspace depends on it. This should be testing - * bprm->secureexec instead. - */ - if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP || - !(uid_eq(current_euid(), current_uid()) && - gid_eq(current_egid(), current_gid()))) - set_dumpable(current->mm, suid_dumpable); - else - set_dumpable(current->mm, SUID_DUMP_USER); - perf_event_exec(); __set_task_comm(me, kbasename(bprm->filename), true); @@ -1480,6 +1506,11 @@ static int prepare_bprm_creds(struct linux_binprm *bprm) if (mutex_lock_interruptible(&current->signal->cred_guard_mutex)) return -ERESTARTNOINTR; + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + return -ERESTARTNOINTR; + } + bprm->cred = prepare_exec_creds(); if (likely(bprm->cred)) return 0; diff --git a/fs/proc/base.c b/fs/proc/base.c index ffd54617c354..0da9adfadb48 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2788,6 +2788,12 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf, if (rv < 0) goto out_free; + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + rv = -ERESTARTNOINTR; + goto out_free; + } + rv = security_setprocattr(PROC_I(inode)->op.lsm, file->f_path.dentry->d_name.name, page, count); diff --git a/include/linux/cred.h b/include/linux/cred.h index f923528d5cc4..b01e309f5686 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -159,6 +159,7 @@ extern const struct cred *get_task_cred(struct task_struct *); extern struct cred *cred_alloc_blank(void); extern struct cred *prepare_creds(void); extern struct cred *prepare_exec_creds(void); +extern bool is_dumpability_changed(const struct cred *, const struct cred *); extern int commit_creds(struct cred *); extern void abort_creds(struct cred *); extern const struct cred *override_creds(const struct cred *); diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 0014d3adaf84..14df7073a0a8 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -234,9 +234,27 @@ struct signal_struct { struct mm_struct *oom_mm; /* recorded mm when the thread group got * killed by the oom killer */ + struct linux_binprm *exec_bprm; /* Used to check ptrace_may_access + * against new credentials while + * de_thread is waiting for other + * traced threads to terminate. + * Set while de_thread is executing. + * The cred_guard_mutex is released + * after de_thread() has called + * zap_other_threads(), therefore + * a fatal signal is guaranteed to be + * already pending in the unlikely + * event, that + * current->signal->exec_bprm happens + * to be non-zero after the + * cred_guard_mutex was acquired. + */ + struct mutex cred_guard_mutex; /* guard against foreign influences on * credential calculations * (notably. ptrace) + * Held while execve runs, except when + * a sibling thread is being traced. * Deprecated do not use in new code. * Use exec_update_lock instead. */ diff --git a/kernel/cred.c b/kernel/cred.c index 98cb4eca23fb..586cb6c7cf6b 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -433,6 +433,28 @@ static bool cred_cap_issubset(const struct cred *set, const struct cred *subset) return false; } +/** + * is_dumpability_changed - Will changing creds from old to new + * affect the dumpability in commit_creds? + * + * Return: false - dumpability will not be changed in commit_creds. + * Return: true - dumpability will be changed to non-dumpable. + * + * @old: The old credentials + * @new: The new credentials + */ +bool is_dumpability_changed(const struct cred *old, const struct cred *new) +{ + if (!uid_eq(old->euid, new->euid) || + !gid_eq(old->egid, new->egid) || + !uid_eq(old->fsuid, new->fsuid) || + !gid_eq(old->fsgid, new->fsgid) || + !cred_cap_issubset(old, new)) + return true; + + return false; +} + /** * commit_creds - Install new credentials upon the current task * @new: The credentials to be assigned @@ -467,11 +489,7 @@ int commit_creds(struct cred *new) get_cred(new); /* we will require a ref for the subj creds too */ /* dumpability changes */ - if (!uid_eq(old->euid, new->euid) || - !gid_eq(old->egid, new->egid) || - !uid_eq(old->fsuid, new->fsuid) || - !gid_eq(old->fsgid, new->fsgid) || - !cred_cap_issubset(old, new)) { + if (is_dumpability_changed(old, new)) { if (task->mm) set_dumpable(task->mm, suid_dumpable); task->pdeath_signal = 0; diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 443057bee87c..eb1c450bb7d7 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -20,6 +20,7 @@ #include <linux/pagemap.h> #include <linux/ptrace.h> #include <linux/security.h> +#include <linux/binfmts.h> #include <linux/signal.h> #include <linux/uio.h> #include <linux/audit.h> @@ -435,6 +436,28 @@ static int ptrace_attach(struct task_struct *task, long request, if (retval) goto unlock_creds; + if (unlikely(task->in_execve)) { + struct linux_binprm *bprm = task->signal->exec_bprm; + const struct cred __rcu *old_cred; + struct mm_struct *old_mm; + + retval = down_write_killable(&task->signal->exec_update_lock); + if (retval) + goto unlock_creds; + task_lock(task); + old_cred = task->real_cred; + old_mm = task->mm; + rcu_assign_pointer(task->real_cred, bprm->cred); + task->mm = bprm->mm; + retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS); + rcu_assign_pointer(task->real_cred, old_cred); + task->mm = old_mm; + task_unlock(task); + up_write(&task->signal->exec_update_lock); + if (retval) + goto unlock_creds; + } + write_lock_irq(&tasklist_lock); retval = -EPERM; if (unlikely(task->exit_state)) @@ -508,6 +531,14 @@ static int ptrace_traceme(void) { int ret = -EPERM; + if (mutex_lock_interruptible(&current->signal->cred_guard_mutex)) + return -ERESTARTNOINTR; + + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + return -ERESTARTNOINTR; + } + write_lock_irq(&tasklist_lock); /* Are we already being traced? */ if (!current->ptrace) { @@ -523,6 +554,7 @@ static int ptrace_traceme(void) } } write_unlock_irq(&tasklist_lock); + mutex_unlock(&current->signal->cred_guard_mutex); return ret; } diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 255999ba9190..b29bbfa0b044 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -1955,9 +1955,15 @@ static long seccomp_set_mode_filter(unsigned int flags, * Make sure we cannot change seccomp or nnp state via TSYNC * while another thread is in the middle of calling exec. */ - if (flags & SECCOMP_FILTER_FLAG_TSYNC && - mutex_lock_killable(&current->signal->cred_guard_mutex)) - goto out_put_fd; + if (flags & SECCOMP_FILTER_FLAG_TSYNC) { + if (mutex_lock_killable(&current->signal->cred_guard_mutex)) + goto out_put_fd; + + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + goto out_put_fd; + } + } spin_lock_irq(&current->sighand->siglock); diff --git a/tools/testing/selftests/ptrace/vmaccess.c b/tools/testing/selftests/ptrace/vmaccess.c index 4db327b44586..3b7d81fb99bb 100644 --- a/tools/testing/selftests/ptrace/vmaccess.c +++ b/tools/testing/selftests/ptrace/vmaccess.c @@ -39,8 +39,15 @@ TEST(vmaccess) f = open(mm, O_RDONLY); ASSERT_GE(f, 0); close(f); - f = kill(pid, SIGCONT); - ASSERT_EQ(f, 0); + f = waitpid(-1, NULL, 0); + ASSERT_NE(f, -1); + ASSERT_NE(f, 0); + ASSERT_NE(f, pid); + f = waitpid(-1, NULL, 0); + ASSERT_EQ(f, pid); + f = waitpid(-1, NULL, 0); + ASSERT_EQ(f, -1); + ASSERT_EQ(errno, ECHILD); } TEST(attach) @@ -57,22 +64,24 @@ TEST(attach) sleep(1); k = ptrace(PTRACE_ATTACH, pid, 0L, 0L); - ASSERT_EQ(errno, EAGAIN); - ASSERT_EQ(k, -1); + ASSERT_EQ(k, 0); k = waitpid(-1, &s, WNOHANG); ASSERT_NE(k, -1); ASSERT_NE(k, 0); ASSERT_NE(k, pid); ASSERT_EQ(WIFEXITED(s), 1); ASSERT_EQ(WEXITSTATUS(s), 0); - sleep(1); - k = ptrace(PTRACE_ATTACH, pid, 0L, 0L); + k = waitpid(-1, &s, 0); + ASSERT_EQ(k, pid); + ASSERT_EQ(WIFSTOPPED(s), 1); + ASSERT_EQ(WSTOPSIG(s), SIGTRAP); + k = ptrace(PTRACE_CONT, pid, 0L, 0L); ASSERT_EQ(k, 0); k = waitpid(-1, &s, 0); ASSERT_EQ(k, pid); ASSERT_EQ(WIFSTOPPED(s), 1); ASSERT_EQ(WSTOPSIG(s), SIGSTOP); - k = ptrace(PTRACE_DETACH, pid, 0L, 0L); + k = ptrace(PTRACE_CONT, pid, 0L, 0L); ASSERT_EQ(k, 0); k = waitpid(-1, &s, 0); ASSERT_EQ(k, pid); -- 2.39.2

11 hours, 24 minutes

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[PATCH net-next] selftests: net: py: handle interrupt during cleanup

by Jakub Kicinski

Following up on the old discussion [1]. Let the BaseExceptions out of defer()'ed cleanup. And handle it in the main loop. This allows us to exit the tests if user hit Ctrl-C during defer(). Link: https://lore.kernel.org/20251119063228.3adfd743@kernel.org # [1] Signed-off-by: Jakub Kicinski <kuba(a)kernel.org> --- CC: shuah(a)kernel.org CC: willemb(a)google.com CC: petrm(a)nvidia.com CC: linux-kselftest(a)vger.kernel.org --- tools/testing/selftests/net/lib/py/ksft.py | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/net/lib/py/ksft.py b/tools/testing/selftests/net/lib/py/ksft.py index ebd82940ee50..531e7fa1b3ea 100644 --- a/tools/testing/selftests/net/lib/py/ksft.py +++ b/tools/testing/selftests/net/lib/py/ksft.py @@ -163,7 +163,7 @@ KSFT_DISRUPTIVE = True entry = global_defer_queue.pop() try: entry.exec_only() - except BaseException: + except Exception: ksft_pr(f"Exception while handling defer / cleanup (callback {i} of {qlen_start})!") tb = traceback.format_exc() for line in tb.strip().split('\n'): @@ -333,7 +333,21 @@ KsftCaseFunction = namedtuple("KsftCaseFunction", KSFT_RESULT = False cnt_key = 'fail' - ksft_flush_defer() + try: + ksft_flush_defer() + except BaseException as e: + tb = traceback.format_exc() + for line in tb.strip().split('\n'): + ksft_pr("Exception|", line) + if isinstance(e, KeyboardInterrupt): + ksft_pr() + ksft_pr("WARN: defer() interrupted, cleanup may be incomplete.") + ksft_pr(" Attempting to finish cleanup before exiting.") + ksft_pr(" Interrupt again to exit immediately.") + ksft_pr() + stop = True + # Flush was interrupted, try to finish the job best we can + ksft_flush_defer() if not cnt_key: cnt_key = 'pass' if KSFT_RESULT else 'fail' -- 2.51.1

11 hours, 53 minutes

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[PATCH net-next] selftests: netconsole: remove log noise due to socat exit

by Andre Carvalho

This removes some noise that can be distracting while looking at selftests by redirecting socat stderr to /dev/null. Before this commit, netcons_basic would output: Running with target mode: basic (ipv6) 2025/11/29 12:08:03 socat[259] W exiting on signal 15 2025/11/29 12:08:03 socat[271] W exiting on signal 15 basic : ipv6 : Test passed Running with target mode: basic (ipv4) 2025/11/29 12:08:05 socat[329] W exiting on signal 15 2025/11/29 12:08:05 socat[322] W exiting on signal 15 basic : ipv4 : Test passed Running with target mode: extended (ipv6) 2025/11/29 12:08:08 socat[386] W exiting on signal 15 2025/11/29 12:08:08 socat[386] W exiting on signal 15 2025/11/29 12:08:08 socat[380] W exiting on signal 15 extended : ipv6 : Test passed Running with target mode: extended (ipv4) 2025/11/29 12:08:10 socat[440] W exiting on signal 15 2025/11/29 12:08:10 socat[435] W exiting on signal 15 2025/11/29 12:08:10 socat[435] W exiting on signal 15 extended : ipv4 : Test passed After these changes, output looks like: Running with target mode: basic (ipv6) basic : ipv6 : Test passed Running with target mode: basic (ipv4) basic : ipv4 : Test passed Running with target mode: extended (ipv6) extended : ipv6 : Test passed Running with target mode: extended (ipv4) extended : ipv4 : Test passed Signed-off-by: Andre Carvalho <asantostc(a)gmail.com> --- tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh index 87f89fd92f8c..ae8abff4be40 100644 --- a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh +++ b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh @@ -249,7 +249,7 @@ function listen_port_and_save_to() { # Just wait for 2 seconds timeout 2 ip netns exec "${NAMESPACE}" \ - socat "${SOCAT_MODE}":"${PORT}",fork "${OUTPUT}" + socat "${SOCAT_MODE}":"${PORT}",fork "${OUTPUT}" 2> /dev/null } # Only validate that the message arrived properly --- base-commit: ff736a286116d462a4067ba258fa351bc0b4ed80 change-id: 20251129-netcons-socat-noise-00e7ccf29560 Best regards, -- Andre Carvalho <asantostc(a)gmail.com>

11 hours, 53 minutes

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