linux-kernel - [PATCH] livepatch: klp_send_signal should treat PF_IO_WORKER like PF

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Date:   Thu, 25 Mar 2021 09:48:36 +0800
From:   Dong Kai <dongkai11@...wei.com>
To:     <jpoimboe@...hat.com>, <jikos@...nel.org>, <mbenes@...e.cz>,
        <pmladek@...e.com>, <joe.lawrence@...hat.com>
CC:     <axboe@...nel.dk>, <live-patching@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] livepatch: klp_send_signal should treat PF_IO_WORKER like PF_KTHREAD

commit 15b2219facad ("kernel: freezer should treat PF_IO_WORKER like
PF_KTHREAD for freezing") is to fix the freezeing issue of IO threads
by making the freezer not send them fake signals.

Here live patching consistency model call klp_send_signals to wake up
all tasks by send fake signal to all non-kthread which only check the
PF_KTHREAD flag, so it still send signal to io threads which may lead to
freezeing issue of io threads.

Here we take the same fix action by treating PF_IO_WORKERS as PF_KTHREAD
within klp_send_signal function.

Signed-off-by: Dong Kai <dongkai11@...wei.com>
---
note:
the io threads freeze issue links:
[1] https://lore.kernel.org/io-uring/YEgnIp43%2F6kFn8GL@kevinlocke.name/
[2] https://lore.kernel.org/io-uring/d7350ce7-17dc-75d7-611b-27ebf2cb539b@kernel.dk/

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

diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index f6310f848f34..0e1c35c8f4b4 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -358,7 +358,7 @@ static void klp_send_signals(void)
 		 * Meanwhile the task could migrate itself and the action
 		 * would be meaningless. It is not serious though.
 		 */
-		if (task->flags & PF_KTHREAD) {
+		if (task->flags & (PF_KTHREAD | PF_IO_WORKER)) {
 			/*
 			 * Wake up a kthread which sleeps interruptedly and
 			 * still has not been migrated.
-- 
2.17.1