Re: [PATCH] livepatch: klp_send_signal should treat PF_IO_WORKER like PF_KTHREAD
From: Joe Lawrence <joe.lawrence@redhat.com>
Date: 2021-03-25 02:52:52
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On 3/24/21 9:48 PM, Dong Kai wrote:
commit 15b2219facad ("kernel: freezer should treat PF_IO_WORKER like
PF_KTHREAD for freezing") is to fix the freezeing issue of IO threadsnit: s/freezeing/freezing
quoted hunk ↗ jump to hunk
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 <redacted> --- note: the io threads freeze issue links: [1] https://lore.kernel.org/io-uring/YEgnIp43%2F6kFn8GL@kevinlocke.name/ (local) [2] https://lore.kernel.org/io-uring/d7350ce7-17dc-75d7-611b-27ebf2cb539b@kernel.dk/ (local) 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.
(PF_KTHREAD | PF_IO_WORKER) is open coded in soo many places maybe this is a silly question, but... If the livepatch code could use fake_signal_wake_up(), we could consolidate the pattern in klp_send_signals() with the one in freeze_task(). Then there would only one place for wake up / fake signal logic. I don't fully understand the differences in the freeze_task() version, so I only pose this as a question and not v2 request. As it is, this change seems logical to me, so: Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Thanks, -- Joe