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Date:   Mon, 14 Feb 2022 10:35:22 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Paul Menzel <pmenzel@molgen.mpg.de>
Cc:     Michael Ellerman <mpe@ellerman.id.au>,
        linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Jason Baron <jbaron@akamai.com>, rcu@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Zhouyi Zhou <zhouzhouyi@gmail.com>, christophe.leroy@csgroup.eu
Subject: Re: BUG: sleeping function called from invalid context at
 include/linux/sched/mm.h:256
Message-ID: <YgoiWlNZvTusk1B9@hirez.programming.kicks-ass.net>
References: <244218af-df6a-236e-0a52-268247dd8271@molgen.mpg.de>
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On Sun, Feb 13, 2022 at 12:05:50AM +0100, Paul Menzel wrote:

> [    0.012154][    T1] BUG: sleeping function called from invalid context at

> [    0.022443][    T1] [c0000000084837d0] [c000000000961aac] > dump_stack_lvl+0xa0/0xec (unreliable)
> [    0.023356][    T1] [c000000008483820] [c00000000019b314] > __might_resched+0x2f4/0x310
> [    0.024174][    T1] [c0000000084838b0] [c0000000004c0c70] > kmem_cache_alloc+0x220/0x4b0
> [    0.025000][    T1] [c000000008483920] [c000000000448af4] > __pud_alloc+0x74/0x1d0
> [    0.025772][    T1] [c000000008483970] [c00000000008fe3c] > hash__map_kernel_page+0x2cc/0x390
> [    0.026643][    T1] [c000000008483a20] [c0000000000a9944] > do_patch_instruction+0x134/0x4a0

do_patch_instruction() rightfully disables IRQs, but then it goes and
tries a memory alloc, which seems a bit daft.

I'm thinking Christophe might know more... he's recently been poking at
Power text poking..