From: Peter Zijlstra <peterz@infradead.org>
To: Zihuan Zhang <zhangzihuan@kylinos.cn>
Cc: rafael@kernel.org, len.brown@intel.com, pavel@kernel.org,
kees@kernel.org, mingo@redhat.com, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
vschneid@redhat.com, akpm@linux-foundation.org, david@redhat.com,
lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com,
vbabka@suse.cz, rppt@kernel.org, surenb@google.com,
mhocko@suse.com, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC PATCH] PM: Optionally block user fork during freeze to improve performance
Date: Fri, 6 Jun 2025 10:22:44 +0200 [thread overview]
Message-ID: <20250606082244.GL30486@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20250606062502.19607-1-zhangzihuan@kylinos.cn>
On Fri, Jun 06, 2025 at 02:25:02PM +0800, Zihuan Zhang wrote:
> @@ -2596,6 +2597,11 @@ pid_t kernel_clone(struct kernel_clone_args *args)
> trace = 0;
> }
>
> +#ifdef CONFIG_PM_DISABLE_USER_FORK_DURING_FREEZE
> + if (pm_should_block_fork() && !(current->flags & PF_KTHREAD))
> + return -EBUSY;
> +#endif
> +
> p = copy_process(NULL, trace, NUMA_NO_NODE, args);
> add_latent_entropy();
This isn't blocking fork(), this is failing fork(). Huge difference.
Also problematic, because -EBUSY is not a recognised return value of
fork(). As such, no existing software will adequately handle it.
next prev parent reply other threads:[~2025-06-06 8:23 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-06 6:25 [RFC PATCH] PM: Optionally block user fork during freeze to improve performance Zihuan Zhang
2025-06-06 7:20 ` David Hildenbrand
2025-06-08 7:22 ` zhangzihuan
2025-06-08 15:50 ` Mateusz Guzik
2025-06-09 3:46 ` zhangzihuan
2025-06-06 8:22 ` Peter Zijlstra [this message]
2025-06-09 4:05 ` zhangzihuan
2025-06-10 10:50 ` David Hildenbrand
2025-06-13 2:37 ` Zihuan Zhang
2025-06-13 7:05 ` Michal Hocko
2025-06-16 3:46 ` Zihuan Zhang
2025-06-16 7:45 ` David Hildenbrand
2025-06-16 11:24 ` Michal Hocko
2025-06-18 11:30 ` Zihuan Zhang
2025-06-18 11:54 ` David Hildenbrand
2025-07-28 13:06 ` Zihuan Zhang
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