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From: Al Viro <viro@ZenIV.linux.org.uk>
To: Larry Finger <Larry.Finger@lwfinger.net>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Thorsten Leemhuis <regressions@leemhuis.info>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: Regression in kernel 4.12-rc1 for Powerpc 32 - bisected to commit 3448890c32c3
Date: Sun, 25 Jun 2017 12:14:04 +0100	[thread overview]
Message-ID: <20170625111404.GV10672@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20170625095351.GU10672@ZenIV.linux.org.uk>

On Sun, Jun 25, 2017 at 10:53:58AM +0100, Al Viro wrote:
> On Sat, Jun 24, 2017 at 12:29:23PM -0500, Larry Finger wrote:
> 
> > I made a break through. If I turn off inline copy to/from users for 32-bit
> > ppc with the following patch, then the system boots:
> 
> OK...  So it's 4.6.3 miscompiling something - it is hardware-independent,
> reproduced in qemu.  I'd like to get more self-contained example of
> miscompile, though; should be done by tonight...

OK, it's the call in rw_copy_check_uvector(); with INLINE_COPY_FROM_USER
it's miscompiled by 4.6.3.  I hadn't looked through the generated code
yet; will do that after I grab some sleep.

  reply	other threads:[~2017-06-25 11:14 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-01 16:39 Regression in kernel 4.12-rc1 for Powerpc 32 - partially bisected Larry Finger
2017-06-21 15:10 ` Regression in kernel 4.12-rc1 for Powerpc 32 - bisected to commit 3448890c32c3 Larry Finger
2017-06-21 21:22   ` Al Viro
2017-06-21 21:31     ` Larry Finger
2017-06-21 21:34       ` Al Viro
2017-06-21 21:49         ` Larry Finger
2017-06-22 14:12           ` Al Viro
2017-06-22 14:19             ` Larry Finger
2017-06-22 19:25               ` Al Viro
2017-06-22 21:41                 ` Al Viro
2017-06-23 18:49                 ` Larry Finger
2017-06-23 20:29                   ` Al Viro
2017-06-24  0:04                     ` Larry Finger
2017-06-24 17:29                     ` Larry Finger
2017-06-25  9:53                       ` Al Viro
2017-06-25 11:14                         ` Al Viro [this message]
2017-06-25 20:53                           ` gcc 4.6.3 miscompile on ppc32 (was Re: Regression in kernel 4.12-rc1 for Powerpc 32 - bisected to commit 3448890c32c3) Al Viro
2017-06-25 21:44                             ` Segher Boessenkool
2017-06-25 22:21                               ` Al Viro
2017-06-26 13:37                                 ` Michael Ellerman
2017-06-26 13:40                       ` Regression in kernel 4.12-rc1 for Powerpc 32 - bisected to commit 3448890c32c3 Michael Ellerman

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