On Wed, Feb 25, 2015 at 05:21:54PM +0100, Arnd Bergmann wrote: > On Wednesday 25 February 2015 11:11:28 Pranith Kumar wrote: > > On Wed, Feb 25, 2015 at 10:58 AM, Arnd Bergmann <a...@arndb.de> wrote: > > > On Wednesday 25 February 2015 10:36:20 Pranith Kumar wrote: > > >> This patch adds support for a half-word xchg() for ARM using > > >> ldrexh/strexh > > >> instructions. It also fixes an asm comment for __cmpxchg2. > > >> > > >> Currently using a half-word xchg() results in the following splat on an > > >> ARMv7 > > >> machine. > > >> > > >> [ 45.833303] xchg: bad data size: pc 0xbe806020, ptr 0xeb18deee, size 2 > > >> [ 45.833324] ------------[ cut here ]------------ > > >> [ 45.837939] kernel BUG at > > >> /dvs/git/dirty/git-master_linux/kernel/arch/arm/kernel/traps.c:727! > > >> > > >> Signed-off-by: Pranith Kumar <bobby.pr...@gmail.com> > > > > > > Unfortunately, the BUG message seems incomplete, can you reproduce this > > > with CONFIG_DEBUG_BUGVERBOSE enabled? > > > > The bug here is in a module caused when xchg() was used on uint16_t > > variable. It is caused by the __bad_xchg() for 2 byte swap. > > > > More information: > > [ 45.833303] xchg: bad data size: pc 0xbe806020, ptr 0xeb18deee, size 2 > > [ 45.833324] ------------[ cut here ]------------ > > [ 45.837939] kernel BUG at > > /dvs/git/dirty/git-master_linux/kernel/arch/arm/kernel/traps.c:727! > > [ 45.846450] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM > > [ 45.852275] Modules linked in: test(O+) nvhost_vi > > [ 45.857012] CPU: 0 PID: 1848 Comm: insmod Tainted: G O > > 3.10.24-g6a2d13a #1 > > [ 45.864744] task: ee406580 ti: eb18c000 task.ti: eb18c000 > > [ 45.870141] PC is at __bad_xchg+0x24/0x28 > > [ 45.874146] LR is at __bad_xchg+0x24/0x28 > > I'm more interested in the backtrace here, it's possible we should fix the > driver instead.
Actually, I think we ought to get rid of __bad_xchg() so that cases like this cause a link error instead of a runtime error, just like we do in other cases as well. That's something that goes back ages (it used to be called something like invalidptr in 2.0 kernels...) -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/