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Date: Thu, 24 May 2018 13:49:31 +0100
From: Will Deacon <will.deacon@arm.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: psodagud@codeaurora.org, Kees Cook <keescook@chromium.org>,
        Andy Lutomirski <luto@amacapital.net>, Will Drewry <wad@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>,
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        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Boqun Feng <boqun.feng@gmail.com>
Subject: Re: write_lock_irq(&tasklist_lock)
Message-ID: <20180524124928.GH8689@arm.com>
References: <0879f797135033e05e8e9166a3c85628@codeaurora.org>
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On Wed, May 23, 2018 at 09:26:35AM -0700, Linus Torvalds wrote:
> On Wed, May 23, 2018 at 8:35 AM Will Deacon <will.deacon@arm.com> wrote:
> 
> > In other words, qrwlock requires consistent locking order wrt spinlocks.
> 
> I *thought* lockdep already tracked and detected this. Or is that only with
> with the sleeping versions?

There are patches in-flight to detect this:

https://marc.info/?l=linux-kernel&m=152483640529740&w=2k

as part of Boqun's work into recursive read locking.

Will