linux-kernel - Re: [PATCH 1/1] sched: panic, when call schedule with preemption disable

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Date:   Tue, 26 Nov 2019 21:11:30 +0800
From:   Kathleen Chang <yt.chang@...iatek.com>
To:     Peter Zijlstra <peterz@...radead.org>
CC:     Matthias Brugger <matthias.bgg@...il.com>,
        <wsd_upstream@...iatek.com>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH 1/1] sched: panic, when call schedule with preemption
 disable

On Thu, 2019-11-21 at 13:30 +0100, Peter Zijlstra wrote:
> On Thu, Nov 21, 2019 at 04:13:05PM +0800, YT Chang wrote:
> > When preemption is disable, call schedule() is incorrect behavior.
> > Suggest to panic directly rather than depend on panic_on_warn.
> 
> Why!?


1. Panic directly will easily find the root cause. 

   Call scheduling in atomic affects not only performance but also
system stability. 
    ex: 
      Call scheduling in IRQ will result in IRQ enable after schedule() 

2. A lot of warnings depend on panic_on_warn. It is not practical to
set panic_on_warn=1.