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Date:   Sun, 13 Feb 2022 04:09:28 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Zhouyi Zhou <zhouzhouyi@gmail.com>
Cc:     Paul Menzel <pmenzel@molgen.mpg.de>,
        Michael Ellerman <mpe@ellerman.id.au>,
        linuxppc-dev@lists.ozlabs.org, Linux-MM <linux-mm@kvack.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Jason Baron <jbaron@akamai.com>, rcu <rcu@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        "Paul E. McKenney" <paulmck@kernel.org>
Subject: Re: BUG: sleeping function called from invalid context at
 include/linux/sched/mm.h:256
Message-ID: <YgiEeHzz4JZFszJD@casper.infradead.org>
References: <244218af-df6a-236e-0a52-268247dd8271@molgen.mpg.de>
 <CAABZP2ycCjiZ0CySc2Lgr_DnUfuDf1iagEKnWwNEkVkR9-gADA@mail.gmail.com>
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On Sun, Feb 13, 2022 at 11:19:09AM +0800, Zhouyi Zhou wrote:
> I think the key to the problem lies in your attached console.log
> (pasted below), at times 0.014987 and 0.015995, I see there are two
> locks (cpu_hotplug_lock and jump_label_mutex)  holded while
> kmem_cache_alloc calls __might_resched (0.023356).

Those are both sleeping locks (a percpu_rwsem and mutex, respectively).
There is no problem with sleeping while holding a mutex or rwsem.