The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x e22f910a26cc2a3ac9c66b8e935ef2a7dd881117 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024081239-cubbyhole-wise-c8d1@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

e22f910a26cc ("sched/smt: Fix unbalance sched_smt_present dec/inc") 2558aacff858 ("sched/hotplug: Ensure only per-cpu kthreads run during hotplug") 565790d28b1e ("sched: Fix balance_callback()")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e22f910a26cc2a3ac9c66b8e935ef2a7dd881117 Mon Sep 17 00:00:00 2001 From: Yang Yingliang yangyingliang@huawei.com Date: Wed, 3 Jul 2024 11:16:08 +0800 Subject: [PATCH] sched/smt: Fix unbalance sched_smt_present dec/inc

I got the following warn report while doing stress test:

jump label: negative count! WARNING: CPU: 3 PID: 38 at kernel/jump_label.c:263 static_key_slow_try_dec+0x9d/0xb0 Call Trace: <TASK> __static_key_slow_dec_cpuslocked+0x16/0x70 sched_cpu_deactivate+0x26e/0x2a0 cpuhp_invoke_callback+0x3ad/0x10d0 cpuhp_thread_fun+0x3f5/0x680 smpboot_thread_fn+0x56d/0x8d0 kthread+0x309/0x400 ret_from_fork+0x41/0x70 ret_from_fork_asm+0x1b/0x30 </TASK>

Because when cpuset_cpu_inactive() fails in sched_cpu_deactivate(), the cpu offline failed, but sched_smt_present is decremented before calling sched_cpu_deactivate(), it leads to unbalanced dec/inc, so fix it by incrementing sched_smt_present in the error path.

Fixes: c5511d03ec09 ("sched/smt: Make sched_smt_present track topology") Cc: stable@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Chen Yu yu.c.chen@intel.com Reviewed-by: Tim Chen tim.c.chen@linux.intel.com Link: https://lore.kernel.org/r/20240703031610.587047-3-yangyingliang@huaweicloud....

diff --git a/kernel/sched/core.c b/kernel/sched/core.c index acc04ed9dbc2..949473e414f9 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8009,6 +8009,7 @@ int sched_cpu_deactivate(unsigned int cpu) sched_update_numa(cpu, false); ret = cpuset_cpu_inactive(cpu); if (ret) { + sched_smt_present_inc(cpu); balance_push_set(cpu, false); set_cpu_active(cpu, true); sched_update_numa(cpu, true);