From: Valentin Schneider <vschneid@redhat.com>
To: Wander Lairson Costa <wander@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
Ian Rogers <irogers@google.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>,
Boqun Feng <boqun.feng@gmail.com>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Wander Lairson Costa <wander@redhat.com>,
Huacai Chen <chenhuacai@kernel.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Oleg Nesterov <oleg@redhat.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Christian Brauner <brauner@kernel.org>,
Kees Cook <keescook@chromium.org>,
Andrei Vagin <avagin@gmail.com>,
Shakeel Butt <shakeelb@google.com>,
open list <linux-kernel@vger.kernel.org>,
"open list:PERFORMANCE EVENTS SUBSYSTEM"
<linux-perf-users@vger.kernel.org>
Subject: Re: [PATCH v7 0/3] Introduce put_task_struct_atomic_sleep()
Date: Wed, 26 Apr 2023 13:05:59 +0100 [thread overview]
Message-ID: <xhsmhr0s6kfvc.mognet@vschneid.remote.csb> (raw)
In-Reply-To: <20230425114307.36889-1-wander@redhat.com>
On 25/04/23 08:43, Wander Lairson Costa wrote:
> The put_task_struct() function reduces a usage counter and invokes
> __put_task_struct() when the counter reaches zero.
>
> In the case of __put_task_struct(), it indirectly acquires a spinlock,
> which operates as a sleeping lock under the PREEMPT_RT configuration.
> As a result, invoking put_task_struct() within an atomic context is
> not feasible for real-time (RT) kernels.
>
> One practical example is a splat inside inactive_task_timer(), which is
> called in a interrupt context:
>
> CPU: 1 PID: 2848 Comm: life Kdump: loaded Tainted: G W ---------
> Hardware name: HP ProLiant DL388p Gen8, BIOS P70 07/15/2012
> Call Trace:
> dump_stack_lvl+0x57/0x7d
> mark_lock_irq.cold+0x33/0xba
> ? stack_trace_save+0x4b/0x70
> ? save_trace+0x55/0x150
> mark_lock+0x1e7/0x400
> mark_usage+0x11d/0x140
> __lock_acquire+0x30d/0x930
> lock_acquire.part.0+0x9c/0x210
> ? refill_obj_stock+0x3d/0x3a0
> ? rcu_read_lock_sched_held+0x3f/0x70
> ? trace_lock_acquire+0x38/0x140
> ? lock_acquire+0x30/0x80
> ? refill_obj_stock+0x3d/0x3a0
> rt_spin_lock+0x27/0xe0
> ? refill_obj_stock+0x3d/0x3a0
> refill_obj_stock+0x3d/0x3a0
> ? inactive_task_timer+0x1ad/0x340
> kmem_cache_free+0x357/0x560
> inactive_task_timer+0x1ad/0x340
> ? switched_from_dl+0x2d0/0x2d0
> __run_hrtimer+0x8a/0x1a0
> __hrtimer_run_queues+0x91/0x130
> hrtimer_interrupt+0x10f/0x220
> __sysvec_apic_timer_interrupt+0x7b/0xd0
> sysvec_apic_timer_interrupt+0x4f/0xd0
> ? asm_sysvec_apic_timer_interrupt+0xa/0x20
> asm_sysvec_apic_timer_interrupt+0x12/0x20
> RIP: 0033:0x7fff196bf6f5
>
> To address this issue, this patch series introduces a new function
> called put_task_struct_atomic_safe(). When compiled with the
> PREEMPT_RT configuration, this function defers the call to
> __put_task_struct() to a process context.
>
> Additionally, the patch series rectifies known problematic call sites
> to ensure smooth functioning.
>
It took me a bit of time to grok the put_task_struct_rcu_user() vs
delayed_free_task() vs put_task_struct_atomic_safe() situation, but other
than that the patches LGTM.
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
next prev parent reply other threads:[~2023-04-26 12:06 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-25 11:43 [PATCH v7 0/3] Introduce put_task_struct_atomic_sleep() Wander Lairson Costa
2023-04-25 11:43 ` [PATCH v7 1/3] sched/core: warn on call put_task_struct in invalid context Wander Lairson Costa
2023-04-28 16:17 ` Sebastian Andrzej Siewior
2023-05-02 14:46 ` Wander Lairson Costa
2023-04-25 11:43 ` [PATCH v7 2/3] sched/task: Add the put_task_struct_atomic_safe() function Wander Lairson Costa
2023-05-04 8:42 ` Peter Zijlstra
2023-05-04 9:32 ` Valentin Schneider
2023-05-04 12:24 ` Wander Lairson Costa
2023-05-04 12:24 ` Wander Lairson Costa
2023-05-04 12:29 ` Oleg Nesterov
2023-05-04 14:33 ` Peter Zijlstra
2023-05-04 14:55 ` Wander Lairson Costa
2023-05-04 15:23 ` Oleg Nesterov
2023-05-04 15:30 ` Peter Zijlstra
2023-05-05 13:39 ` Peter Zijlstra
2023-05-04 18:29 ` Wander Lairson Costa
2023-05-04 19:22 ` Oleg Nesterov
2023-05-04 19:38 ` Wander Lairson Costa
2023-05-04 20:16 ` Oleg Nesterov
2023-05-08 12:30 ` Wander Lairson Costa
2023-05-04 15:24 ` Peter Zijlstra
2023-05-04 18:21 ` Wander Lairson Costa
2023-05-05 13:32 ` Peter Zijlstra
2023-05-05 14:26 ` Steven Rostedt
2023-05-05 14:29 ` Steven Rostedt
2023-05-08 12:28 ` Wander Lairson Costa
2023-04-25 11:43 ` [PATCH v7 3/3] treewide: replace put_task_struct() with the atomic safe version Wander Lairson Costa
2023-04-26 12:05 ` Valentin Schneider [this message]
2023-04-26 17:44 ` [PATCH v7 0/3] Introduce put_task_struct_atomic_sleep() Waiman Long
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