Re: [PATCH v2 5/8] kernel: convert process/thread iterators to for_each_*_rculock
From: Gregory Price <gourry@gourry.net>
Date: 2026-09-07 15:53:55
Also in:
linux-fsdevel, linux-mm, linux-security-module, linux-trace-kernel, lkml, rcu
On Mon, Sep 07, 2026 at 04:13:31PM +0800, Ye Liu wrote:
From: Ye Liu <liuye@kylinos.cn> Replace the manual rcu_read_lock()/rcu_read_unlock() and guard(rcu) pairs combined with for_each_process(), for_each_thread() and for_each_process_thread() loops across kernel/ with the for_each_*_rculock() macros, which scope the RCU read lock to the loop body via scoped_guard(rcu). No functional change. Signed-off-by: Ye Liu <liuye@kylinos.cn> Acked-by: Michal Hocko <mhocko@suse.com>
Question below
quoted hunk ↗ jump to hunk
diff --git a/kernel/hung_task.c b/kernel/hung_task.c index 6fcc94ce4ca9..73a5ad3be9a8 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c@@ -315,13 +315,12 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) return; this_round_count = 0; - rcu_read_lock(); - for_each_process_thread(g, t) { + for_each_process_thread_rculock(g, t) { if (!max_count--) - goto unlock; + goto out;
... snip ...
- unlock: - rcu_read_unlock(); - +out: if (!this_round_count) return;
The sunken rcu_read_lock()/unlock() + scoped_guard usage makes this goto at a minimum very confusing, if not actually broken. Are we sure this isn't broken as-written? Generally we don't mix cleanup and goto for exactly this reason. ~Gregory