linux-kernel - Re: [PATCH 6/9] lockdep: Introduce wait-type checks

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Message-ID: <20200331134249.kf3zyf27xtspmlif@linutronix.de>
Date:   Tue, 31 Mar 2020 15:42:49 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>, Will Deacon <will@...nel.org>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>
Subject: Re: [PATCH 6/9] lockdep: Introduce wait-type checks

On 2020-03-31 15:25:21 [+0200], Geert Uytterhoeven wrote:
> Hi all,
Hi Geert,

> On arm64 (e.g. R-Car H3 ES2.0):
> 
> +=============================
> +[ BUG: Invalid wait context ]
> +5.6.0-salvator-x-09423-gb29514ba13a9c459-dirty #679 Not tainted
> +-----------------------------
> +swapper/5/0 is trying to lock:
> +ffffff86ff76f398 (&pool->lock){..-.}-{3:3}, at: __queue_work+0x134/0x430

The pool->lock is not yet converted.
…
> On arm32 (e.g SH-Mobile AG5, using Cortex-A9 TWD):
> 
> +=============================
> +[ BUG: Invalid wait context ]
> +5.6.0-kzm9g-09424-g2698719b4c4f35db-dirty #253 Not tainted
> +-----------------------------
> +swapper/0/0 is trying to lock:
> +dfbc5250 (&pool->lock){..-.}-{3:3}, at: __queue_work+0x14c/0x4d0

same issue.

> I also see it on other arm32 platforms using Renesas-specific timers,
> but I'll ignore those until the issues with "standard" ARM timers have
> been resolved ;-)

There are some known culprits, like the work infrastructure. The printk
is another one. From Kconfig:

|   NOTE: There are known nesting problems. So if you enable this
|   option expect lockdep splats until these problems have been fully
|   addressed which is work in progress. This config switch allows to
|   identify and analyze these problems. It will be removed and the
|   check permanentely enabled once the main issues have been fixed.


> Thanks!
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> 

Sebastian