Re: bit tweaks [was: Re: [nfsd4] potentially hardware breaking regression in 4.14-rc and 4.13.11]

From: Rasmus Villemoes
Date: Tue Nov 14 2017 - 18:53:18 EST


On 14 November 2017 at 23:43, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, Nov 14, 2017 at 2:24 PM, Rasmus Villemoes
> <linux@xxxxxxxxxxxxxxxxxx> wrote:
>>
>> Can you be more specific? That's not what I see with gcc 7.1.
>
> I have gcc-7.2.1, and it made a horrible mess of the do_mount() code.

Odd. 7.2 and 7.1 (both of which I've just compiled from source, no
special configure flags or anything) generate exactly the same (good)
code for fs/namespace.o after patching. I also tried with
CONFIG_CC_OPTIMIZE_FOR_SIZE=y just in case, but that still produces
reasonable code. Oh well.

Rasmus