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Date: Fri, 4 Apr 2003 05:17:50 +1000
From: Anton Blanchard <anton@samba.org>
To: Pete Zaitcev <zaitcev@redhat.com>
Cc: riel@redhat.com, linux-kernel@vger.kernel.org, linux390@de.ibm.com
Subject: Re: gcc-3.2 breaks rmap on s390x
Message-ID: <20030403191750.GE27733@krispykreme>
References: <20030403131054.B25676@devserv.devel.redhat.com>
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> the following patch seems to fix my rmap problems on s390x.
> 
> --- linux-2.4.20-2.1.24.z1/include/linux/mm.h	2003-03-27 21:30:09.000000000 -0500
> +++ linux-2.4.20-2.1.24.z2/include/linux/mm.h	2003-04-02 20:26:11.000000000 -0500
> @@ -376,8 +376,10 @@
>  	 */
>  #ifdef CONFIG_SMP
>  	while (test_and_set_bit(PG_chainlock, &page->flags)) {
> -		while (test_bit(PG_chainlock, &page->flags))
> +		while (test_bit(PG_chainlock, &page->flags)) {
>  			cpu_relax();
> +			barrier();
> +		}
>  	}
>  #endif
>  }

cpu_relax() should be a gcc barrier. Its this way on all architectures in
2.5.

Anton