user/sven/linux.git/kernel, branch v6.6.79

clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context

2025-02-21T12:57:20Z

[ Upstream commit 6bb05a33337b2c842373857b63de5c9bf1ae2a09 ] The following bug report happened with a PREEMPT_RT kernel: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2012, name: kwatchdog preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 get_random_u32+0x4f/0x110 clocksource_verify_choose_cpus+0xab/0x1a0 clocksource_verify_percpu.part.0+0x6b/0x330 clocksource_watchdog_kthread+0x193/0x1a0 It is due to the fact that clocksource_verify_choose_cpus() is invoked with preemption disabled. This function invokes get_random_u32() to obtain random numbers for choosing CPUs. The batched_entropy_32 local lock and/or the base_crng.lock spinlock in driver/char/random.c will be acquired during the call. In PREEMPT_RT kernel, they are both sleeping locks and so cannot be acquired in atomic context. Fix this problem by using migrate_disable() to allow smp_processor_id() to be reliably used without introducing atomic context. preempt_disable() is then called after clocksource_verify_choose_cpus() but before the clocksource measurement is being run to avoid introducing unexpected latency. Fixes: 7560c02bdffb ("clocksource: Check per-CPU clock synchronization when marked unstable") Suggested-by: Sebastian Andrzej Siewior Signed-off-by: Waiman Long Signed-off-by: Thomas Gleixner Reviewed-by: Paul E. McKenney Reviewed-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/all/20250131173323.891943-2-longman@redhat.com Signed-off-by: Sasha Levin

clocksource: Use pr_info() for "Checking clocksource synchronization" message

2025-02-21T12:57:19Z

[ Upstream commit 1f566840a82982141f94086061927a90e79440e5 ] The "Checking clocksource synchronization" message is normally printed when clocksource_verify_percpu() is called for a given clocksource if both the CLOCK_SOURCE_UNSTABLE and CLOCK_SOURCE_VERIFY_PERCPU flags are set. It is an informational message and so pr_info() is the correct choice. Signed-off-by: Waiman Long Signed-off-by: Thomas Gleixner Reviewed-by: Paul E. McKenney Acked-by: John Stultz Link: https://lore.kernel.org/all/20250125015442.3740588-1-longman@redhat.com Stable-dep-of: 6bb05a33337b ("clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context") Signed-off-by: Sasha Levin

cgroup: fix race between fork and cgroup.kill

2025-02-21T12:57:17Z

commit b69bb476dee99d564d65d418e9a20acca6f32c3f upstream. Tejun reported the following race between fork() and cgroup.kill at [1]. Tejun: I was looking at cgroup.kill implementation and wondering whether there could be a race window. So, __cgroup_kill() does the following: k1. Set CGRP_KILL. k2. Iterate tasks and deliver SIGKILL. k3. Clear CGRP_KILL. The copy_process() does the following: c1. Copy a bunch of stuff. c2. Grab siglock. c3. Check fatal_signal_pending(). c4. Commit to forking. c5. Release siglock. c6. Call cgroup_post_fork() which puts the task on the css_set and tests CGRP_KILL. The intention seems to be that either a forking task gets SIGKILL and terminates on c3 or it sees CGRP_KILL on c6 and kills the child. However, I don't see what guarantees that k3 can't happen before c6. ie. After a forking task passes c5, k2 can take place and then before the forking task reaches c6, k3 can happen. Then, nobody would send SIGKILL to the child. What am I missing? This is indeed a race. One way to fix this race is by taking cgroup_threadgroup_rwsem in write mode in __cgroup_kill() as the fork() side takes cgroup_threadgroup_rwsem in read mode from cgroup_can_fork() to cgroup_post_fork(). However that would be heavy handed as this adds one more potential stall scenario for cgroup.kill which is usually called under extreme situation like memory pressure. To fix this race, let's maintain a sequence number per cgroup which gets incremented on __cgroup_kill() call. On the fork() side, the cgroup_can_fork() will cache the sequence number locally and recheck it against the cgroup's sequence number at cgroup_post_fork() site. If the sequence numbers mismatch, it means __cgroup_kill() can been called and we should send SIGKILL to the newly created task. Reported-by: Tejun Heo Closes: https://lore.kernel.org/all/Z5QHE2Qn-QZ6M-KW@slm.duckdns.org/ [1] Fixes: 661ee6280931 ("cgroup: introduce cgroup.kill") Cc: stable@vger.kernel.org # v5.14+ Signed-off-by: Shakeel Butt Reviewed-by: Michal Koutný Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

cgroup: Remove steal time from usage_usec

2025-02-21T12:57:08Z

[ Upstream commit db5fd3cf8bf41b84b577b8ad5234ea95f327c9be ] The CPU usage time is the time when user, system or both are using the CPU. Steal time is the time when CPU is waiting to be run by the Hypervisor. It should not be added to the CPU usage time, hence removing it from the usage_usec entry. Fixes: 936f2a70f2077 ("cgroup: add cpu.stat file to root cgroup") Acked-by: Axel Busch Acked-by: Michal Koutný Signed-off-by: Muhammad Adeel Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin

tracing/osnoise: Fix resetting of tracepoints

2025-02-17T08:40:39Z

commit e3ff4245928f948f3eb2e852aa350b870421c358 upstream. If a timerlat tracer is started with the osnoise option OSNOISE_WORKLOAD disabled, but then that option is enabled and timerlat is removed, the tracepoints that were enabled on timerlat registration do not get disabled. If the option is disabled again and timelat is started, then it triggers a warning in the tracepoint code due to registering the tracepoint again without ever disabling it. Do not use the same user space defined options to know to disable the tracepoints when timerlat is removed. Instead, set a global flag when it is enabled and use that flag to know to disable the events. ~# echo NO_OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options ~# echo timerlat > /sys/kernel/tracing/current_tracer ~# echo OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options ~# echo nop > /sys/kernel/tracing/current_tracer ~# echo NO_OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options ~# echo timerlat > /sys/kernel/tracing/current_tracer Triggers: ------------[ cut here ]------------ WARNING: CPU: 6 PID: 1337 at kernel/tracepoint.c:294 tracepoint_add_func+0x3b6/0x3f0 Modules linked in: CPU: 6 UID: 0 PID: 1337 Comm: rtla Not tainted 6.13.0-rc4-test-00018-ga867c441128e-dirty #73 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:tracepoint_add_func+0x3b6/0x3f0 Code: 48 8b 53 28 48 8b 73 20 4c 89 04 24 e8 23 59 11 00 4c 8b 04 24 e9 36 fe ff ff 0f 0b b8 ea ff ff ff 45 84 e4 0f 84 68 fe ff ff <0f> 0b e9 61 fe ff ff 48 8b 7b 18 48 85 ff 0f 84 4f ff ff ff 49 8b RSP: 0018:ffffb9b003a87ca0 EFLAGS: 00010202 RAX: 00000000ffffffef RBX: ffffffff92f30860 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff9bf59e91ccd0 RDI: ffffffff913b6410 RBP: 000000000000000a R08: 00000000000005c7 R09: 0000000000000002 R10: ffffb9b003a87ce0 R11: 0000000000000002 R12: 0000000000000001 R13: ffffb9b003a87ce0 R14: ffffffffffffffef R15: 0000000000000008 FS: 00007fce81209240(0000) GS:ffff9bf6fdd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055e99b728000 CR3: 00000001277c0002 CR4: 0000000000172ef0 Call Trace: ? __warn.cold+0xb7/0x14d ? tracepoint_add_func+0x3b6/0x3f0 ? report_bug+0xea/0x170 ? handle_bug+0x58/0x90 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? __pfx_trace_sched_migrate_callback+0x10/0x10 ? tracepoint_add_func+0x3b6/0x3f0 ? __pfx_trace_sched_migrate_callback+0x10/0x10 ? __pfx_trace_sched_migrate_callback+0x10/0x10 tracepoint_probe_register+0x78/0xb0 ? __pfx_trace_sched_migrate_callback+0x10/0x10 osnoise_workload_start+0x2b5/0x370 timerlat_tracer_init+0x76/0x1b0 tracing_set_tracer+0x244/0x400 tracing_set_trace_write+0xa0/0xe0 vfs_write+0xfc/0x570 ? do_sys_openat2+0x9c/0xe0 ksys_write+0x72/0xf0 do_syscall_64+0x79/0x1c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Tomas Glozar Cc: Gabriele Monaco Cc: Luis Goncalves Cc: John Kacur Link: https://lore.kernel.org/20250123204159.4450c88e@gandalf.local.home Fixes: e88ed227f639e ("tracing/timerlat: Add user-space interface") Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman

printk: Fix signed integer overflow when defining LOG_BUF_LEN_MAX

2025-02-17T08:40:04Z

[ Upstream commit 3d6f83df8ff2d5de84b50377e4f0d45e25311c7a ] Shifting 1 << 31 on a 32-bit int causes signed integer overflow, which leads to undefined behavior. To prevent this, cast 1 to u32 before performing the shift, ensuring well-defined behavior. This change explicitly avoids any potential overflow by ensuring that the shift occurs on an unsigned 32-bit integer. Signed-off-by: Kuan-Wei Chiu Acked-by: Petr Mladek Link: https://lore.kernel.org/r/20240928113608.1438087-1-visitorckw@gmail.com Signed-off-by: Petr Mladek Signed-off-by: Sasha Levin

sched: Don't try to catch up excess steal time.

2025-02-17T08:40:03Z

[ Upstream commit 108ad0999085df2366dd9ef437573955cb3f5586 ] When steal time exceeds the measured delta when updating clock_task, we currently try to catch up the excess in future updates. However, this results in inaccurate run times for the future things using clock_task, in some situations, as they end up getting additional steal time that did not actually happen. This is because there is a window between reading the elapsed time in update_rq_clock() and sampling the steal time in update_rq_clock_task(). If the VCPU gets preempted between those two points, any additional steal time is accounted to the outgoing task even though the calculated delta did not actually contain any of that "stolen" time. When this race happens, we can end up with steal time that exceeds the calculated delta, and the previous code would try to catch up that excess steal time in future clock updates, which is given to the next, incoming task, even though it did not actually have any time stolen. This behavior is particularly bad when steal time can be very long, which we've seen when trying to extend steal time to contain the duration that the host was suspended [0]. When this happens, clock_task stays frozen, during which the running task stays running for the whole duration, since its run time doesn't increase. However the race can happen even under normal operation. Ideally we would read the elapsed cpu time and the steal time atomically, to prevent this race from happening in the first place, but doing so is non-trivial. Since the time between those two points isn't otherwise accounted anywhere, neither to the outgoing task nor the incoming task (because the "end of outgoing task" and "start of incoming task" timestamps are the same), I would argue that the right thing to do is to simply drop any excess steal time, in order to prevent these issues. [0] https://lore.kernel.org/kvm/20240820043543.837914-1-suleiman@google.com/ Signed-off-by: Suleiman Souhlal Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20241118043745.1857272-1-suleiman@google.com Signed-off-by: Sasha Levin

PM: hibernate: Add error handling for syscore_suspend()

2025-02-08T08:52:29Z

[ Upstream commit e20a70c572539a486dbd91b225fa6a194a5e2122 ] In hibernation_platform_enter(), the code did not check the return value of syscore_suspend(), potentially leading to a situation where syscore_resume() would be called even if syscore_suspend() failed. This could cause unpredictable behavior or system instability. Modify the code sequence in question to properly handle errors returned by syscore_suspend(). If an error occurs in the suspend path, the code now jumps to label 'Enable_irqs' skipping the syscore_resume() call and only enabling interrupts after setting the system state to SYSTEM_RUNNING. Fixes: 40dc166cb5dd ("PM / Core: Introduce struct syscore_ops for core subsystems PM") Signed-off-by: Wentao Liang Link: https://patch.msgid.link/20250119143205.2103-1-vulab@iscas.ac.cn [ rjw: Changelog edits ] Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

padata: avoid UAF for reorder_work

2025-02-08T08:52:09Z

[ Upstream commit dd7d37ccf6b11f3d95e797ebe4e9e886d0332600 ] Although the previous patch can avoid ps and ps UAF for _do_serial, it can not avoid potential UAF issue for reorder_work. This issue can happen just as below: crypto_request crypto_request crypto_del_alg padata_do_serial ... padata_reorder // processes all remaining // requests then breaks while (1) { if (!padata) break; ... } padata_do_serial // new request added list_add // sees the new request queue_work(reorder_work) padata_reorder queue_work_on(squeue->work) ... padata_serial_worker // completes new request, // no more outstanding // requests crypto_del_alg // free pd invoke_padata_reorder // UAF of pd To avoid UAF for 'reorder_work', get 'pd' ref before put 'reorder_work' into the 'serial_wq' and put 'pd' ref until the 'serial_wq' finish. Fixes: bbefa1dd6a6d ("crypto: pcrypt - Avoid deadlock by using per-instance padata queues") Signed-off-by: Chen Ridong Acked-by: Daniel Jordan Signed-off-by: Herbert Xu Signed-off-by: Sasha Levin

padata: add pd get/put refcnt helper

2025-02-08T08:52:09Z

[ Upstream commit ae154202cc6a189b035359f3c4e143d5c24d5352 ] Add helpers for pd to get/put refcnt to make code consice. Signed-off-by: Chen Ridong Acked-by: Daniel Jordan Signed-off-by: Herbert Xu Stable-dep-of: dd7d37ccf6b1 ("padata: avoid UAF for reorder_work") Signed-off-by: Sasha Levin