From: Josh Poimboeuf <jpoimboe@kernel.org>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: jikos@kernel.org, mbenes@suse.cz, pmladek@suse.com,
joe.lawrence@redhat.com, live-patching@vger.kernel.org
Subject: Re: [PATCH 3/3] livepatch: Avoid potential RCU stalls in klp transition
Date: Tue, 11 Feb 2025 16:52:53 -0800 [thread overview]
Message-ID: <20250212005253.4d6wru5lsrvxch45@jpoimboe> (raw)
In-Reply-To: <20250211062437.46811-4-laoar.shao@gmail.com>
On Tue, Feb 11, 2025 at 02:24:37PM +0800, Yafang Shao wrote:
> +++ b/kernel/livepatch/transition.c
> @@ -491,9 +491,18 @@ void klp_try_complete_transition(void)
> complete = false;
> break;
> }
> +
> + /* Avoid potential RCU stalls */
> + if (need_resched()) {
> + complete = false;
> + break;
> + }
> }
> read_unlock(&tasklist_lock);
>
> + /* The above operation might be expensive. */
> + cond_resched();
> +
This is also nasty, yet another reason to use rcu_read_lock() if we can.
Also, with the new lazy preemption model, I believe cond_resched() is
pretty much deprecated.
Also, for future patch sets, please also add lkml to cc. Thanks.
--
Josh
next prev parent reply other threads:[~2025-02-12 0:52 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-11 6:24 [PATCH 0/3] livepatch: Some improvements Yafang Shao
2025-02-11 6:24 ` [PATCH 1/3] livepatch: Add comment to clarify klp_add_nops() Yafang Shao
2025-02-12 12:51 ` Petr Mladek
2025-02-13 5:49 ` Yafang Shao
2025-02-11 6:24 ` [PATCH 2/3] livepatch: Avoid blocking tasklist_lock too long Yafang Shao
2025-02-12 0:40 ` Josh Poimboeuf
2025-02-12 2:34 ` Yafang Shao
2025-02-12 11:54 ` Yafang Shao
2025-02-12 15:42 ` Petr Mladek
2025-02-13 1:36 ` Josh Poimboeuf
2025-02-13 5:53 ` Yafang Shao
2025-02-13 9:48 ` Petr Mladek
2025-02-13 17:32 ` Josh Poimboeuf
2025-02-14 14:44 ` Petr Mladek
2025-02-14 18:12 ` Josh Poimboeuf
2025-02-18 2:37 ` Yafang Shao
2025-02-13 2:47 ` Josh Poimboeuf
2025-02-13 11:19 ` Find root of the stall: was: " Petr Mladek
2025-02-13 12:32 ` Yafang Shao
2025-02-13 12:39 ` Yafang Shao
2025-02-14 2:44 ` Yafang Shao
2025-02-14 8:36 ` Josh Poimboeuf
2025-02-14 11:37 ` Petr Mladek
2025-02-18 2:19 ` Yafang Shao
2025-02-14 9:46 ` Petr Mladek
2025-02-11 6:24 ` [PATCH 3/3] livepatch: Avoid potential RCU stalls in klp transition Yafang Shao
2025-02-12 0:52 ` Josh Poimboeuf [this message]
2025-02-12 2:42 ` Yafang Shao
2025-02-13 1:58 ` Josh Poimboeuf
2025-02-13 5:51 ` Yafang Shao
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