From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:45933) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T47nO-0003q3-Gb for qemu-devel@nongnu.org; Wed, 22 Aug 2012 06:04:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1T47nI-0003Gf-L9 for qemu-devel@nongnu.org; Wed, 22 Aug 2012 06:04:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51473) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T47nI-0003GT-C6 for qemu-devel@nongnu.org; Wed, 22 Aug 2012 06:04:12 -0400 Message-ID: <5034AE84.90708@redhat.com> Date: Wed, 22 Aug 2012 13:03:48 +0300 From: Avi Kivity MIME-Version: 1.0 References: <592618508.2357204.1345541334852.JavaMail.root@redhat.com> <5034AC61.9030704@redhat.com> In-Reply-To: <5034AC61.9030704@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] [PATCH] x86, alternative: fix p6 nops on non-modular kernels List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Tomas Racek , the arch/x86 maintainers Cc: kvm-devel , qemu-devel@nongnu.org, Marcelo Tosatti , Michael Tokarev , linux-kernel , Borislav Petkov , Anthony Liguori , "H. Peter Anvin" , Alan Cox , Alan Cox On 08/22/2012 12:54 PM, Avi Kivity wrote: > On 08/21/2012 12:28 PM, Tomas Racek wrote: >> >> http://fi.muni.cz/~xracek/debian2.img.bz2 >> >> Other things are the same. >> >> The runtest.sh sets environment for xfstests and runs test 285 which I wrote and and which should test if FS sends discard requests only on free sectors: >> 285: >> 1. Create loop device and FS on it. >> 2. Populate it with some garbage. >> 3. Get free sectors from FS. >> 4. Run fstrim and look for discard requests via blk tracer. >> 5. Compare free sectors to discard requests. >> >> The test itself can have some issues but I'm pretty sure it shouldn't crash the system. ;-) > > Does the following patch help? > It's obvious that it should. You're running a non-modular kernel, and those nops are discarded (probably a leftover from the days patching was a boot-only activity), so the kernel patched garbage over its own code. -------8<----cut-here-----8<----------------------------------- From: Avi Kivity Date: Wed, 22 Aug 2012 12:58:18 +0300 Subject: [PATCH] x86, alternative: fix p6 nops on non-modular kernels Probably a leftover from the early days of self-patching, p6nops are marked __initconst_or_module, which causes them to be discarded in a non-modular kernel. If something later triggers patching, it will overwrite kernel code with garbage. Reported-by: Tomas Racek Signed-off-by: Avi Kivity diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index afb7ff7..ced4534 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -165,7 +165,7 @@ static int __init setup_noreplace_paravirt(char *str) #endif #ifdef P6_NOP1 -static const unsigned char __initconst_or_module p6nops[] = +static const unsigned char p6nops[] = { P6_NOP1, P6_NOP2, -- error compiling committee.c: too many arguments to function