linux-kernel - [RFC] exit: do exit_task_work() before shooting off mm

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Message-Id: <abab9af4e0d26358538a45a2826650e9cefd2924.1606961931.git.asml.silence@gmail.com>
Date:   Thu,  3 Dec 2020 02:30:46 +0000
From:   Pavel Begunkov <asml.silence@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Jens Axboe <axboe@...nel.dk>
Subject: [RFC] exit: do exit_task_work() before shooting off mm

Handle task works and lock it earlier before it starts killing off
task's resources like mm. io_uring makes use of it a lot and it'd
nicer to have all added task_work finding tasks in a consistent state.

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---

Would it be correct? I clearly don't know all the exit invariants, but
can't find any users relying on task_works in-between.

 kernel/exit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index 1f236ed375f8..c2a0cffd824d 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -763,6 +763,7 @@ void __noreturn do_exit(long code)
 	}
 
 	exit_signals(tsk);  /* sets PF_EXITING */
+	exit_task_work(tsk);
 
 	/* sync mm's RSS info before statistics gathering */
 	if (tsk->mm)
@@ -806,7 +807,6 @@ void __noreturn do_exit(long code)
 	if (group_dead)
 		disassociate_ctty(1);
 	exit_task_namespaces(tsk);
-	exit_task_work(tsk);
 	exit_thread(tsk);
 
 	/*
-- 
2.24.0