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Date:   Thu, 18 Oct 2018 03:49:43 +0100
From:   Al Viro <viro@ZenIV.linux.org.uk>
To:     Andy Lutomirski <luto@amacapital.net>
Cc:     NeilBrown <neilb@suse.com>, Peter Zijlstra <peterz@infradead.org>,
        Dmitry Safonov <dsafonov@virtuozzo.com>,
        Andrew Lutomirski <luto@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@kernel.org>,
        Brian Gerst <brgerst@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-tip-commits@vger.kernel.org, jsimmons@infradead.org
Subject: Re: in_compat_syscall() returns from kernel thread for X86_32.
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On Wed, Oct 17, 2018 at 07:37:42PM -0700, Andy Lutomirski wrote:

> I could get on board with:
> 
> ({WARN_ON_ONCE(current->flags & PF_KTHREAD); true})
> 
> The point of these accessors is to be used *in a syscall*.
> 
> What on Earth is Lustre doing that makes it have this problem?

	Plays with timestamps from a kernel thread, perhaps?
See the old .su joke about adenoidectomy with rectal access
for possible reasons for doing it that way...