linux-kernel - Re: [PATCH 08/10] x86: remove address space overrides using set

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Date:   Sat, 29 Aug 2020 11:25:31 +0200
From:   Christoph Hellwig <hch@....de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Christoph Hellwig <hch@....de>, Al Viro <viro@...iv.linux.org.uk>,
        Michael Ellerman <mpe@...erman.id.au>,
        the arch/x86 maintainers <x86@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH 08/10] x86: remove address space overrides using
 set_fs()

On Thu, Aug 27, 2020 at 11:15:12AM -0700, Linus Torvalds wrote:
> >  SYM_FUNC_START(__put_user_2)
> > -       ENTER
> > -       mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
> > +       LOAD_TASK_SIZE_MAX
> >         sub $1,%_ASM_BX
> 
> It's even more obvious here. We load a constant and then immediately
> do a "sub $1" on that value.
> 
> It's not a huge deal, you don't have to respin the series for this, I
> just wanted to point it out so that people are aware of it and if I
> forget somebody else will hopefully remember that "we should fix that
> too".

The changes seem easy enough and I need to respin at least for the
lkdtm changes, and probaby also for a pending fix in the low-level
x86 code that will hopefully be picked up for 5.9.

But the more important questions is: how do we want to pick the series
up?  Especially due to the splice changes I really want it to be in
linux-next as long as possible.