linux-kernel - Re: [lkp] [net] 1fbe4b46cac: WARNING: CPU: 0 PID: 2245 at kernel/sched/core.c:7376 __might

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Message-ID: <20150804163125.GA31395@redhat.com>
Date:	Tue, 4 Aug 2015 18:31:25 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	kernel test robot <ying.huang@...el.com>
Cc:	lkp@...org, LKML <linux-kernel@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Jesper Brouer <brouer@...hat.com>
Subject: Re: [lkp] [net] 1fbe4b46cac: WARNING: CPU: 0 PID: 2245 at
	kernel/sched/core.c:7376 __might_sleep+0x8b/0xa8()

On 08/03, Oleg Nesterov wrote:
>
> Now that I can actually see the code, I think that we should simply remove
> __set_current_state(TASK_RUNNING) and set_current_state(TASK_INTERRUPTIBLE).
> But let me re-check this once again tomorrow, I simply can't understand why
> pktgen_thread_worker() does this.
>
> Unless I am totally confused they could be removed right after ef87979c273a2
> "pktgen: better scheduler friendliness" which in particular changed the main
> loop to use wait_event(). Then later baac167b "pktgen: avoid expensive
> set_current_state() call in loop" changed the 1st __set_current_state() to
> set RUNNING, and moved the 2nd set_current_state(TASK_INTERRUPTIBLE) outside
> the main loop for absolutely no reason.

Yes, I am sending the patch. Both set_current_state()'s look obviously unneeded,
and afaics we could hit the same warning even without 1fbe4b46caca. At least
pktgen_rem_thread()->remove_proc_entry() can sleep.

Oleg.

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