Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2015-03-05 Thread H. Peter Anvin
On 06/23/2014 06:08 AM, Konrad Rzeszutek Wilk wrote: On Wed, Mar 19, 2014 at 08:02:22AM -0700, H. Peter Anvin wrote: On 03/19/2014 06:21 AM, Konrad Rzeszutek Wilk wrote: The following patch does the always eager allocation. It's a fixup of Suresh's original patch. Hey Peter, I think

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-06-23 Thread Konrad Rzeszutek Wilk
On Wed, Mar 19, 2014 at 08:02:22AM -0700, H. Peter Anvin wrote: On 03/19/2014 06:21 AM, Konrad Rzeszutek Wilk wrote: The following patch does the always eager allocation. It's a fixup of Suresh's original patch. Hey Peter, I think this is the solution you were looking for?

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-19 Thread Konrad Rzeszutek Wilk
On Mon, Mar 17, 2014 at 01:29:03PM +, David Vrabel wrote: On 17/03/14 03:43, H. Peter Anvin wrote: On 03/16/2014 08:35 PM, Sarah Newman wrote: Can you please review my patch first? It's only enabled when absolutely required. It doesn't help. It means you're running on Xen, and

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-19 Thread H. Peter Anvin
On 03/19/2014 06:21 AM, Konrad Rzeszutek Wilk wrote: The following patch does the always eager allocation. It's a fixup of Suresh's original patch. Hey Peter, I think this is the solution you were looking for? Or are there some other subtle issues that you think lurk around? Ah, I

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-19 Thread Greg Kroah-Hartman
On Sun, Mar 16, 2014 at 09:23:01PM -0700, H. Peter Anvin wrote: On 03/16/2014 09:12 PM, Sarah Newman wrote: Unconditional eager allocation works. Can xen users count on this being included and applied to the stable kernels? I don't know. If we state that it is a bug fix for Xen

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-19 Thread H. Peter Anvin
Sounds good. On March 19, 2014 5:00:11 PM PDT, Greg Kroah-Hartman gre...@linuxfoundation.org wrote: On Sun, Mar 16, 2014 at 09:23:01PM -0700, H. Peter Anvin wrote: On 03/16/2014 09:12 PM, Sarah Newman wrote: Unconditional eager allocation works. Can xen users count on this being included

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-18 Thread Ingo Molnar
* H. Peter Anvin h...@zytor.com wrote: On 03/17/2014 10:05 AM, Jan Beulich wrote: I don't think so - while it (as we now see) disallows certain things inside the guest, back at the time when this was designed there was no sign of any sort of allocation/scheduling being done inside the

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-18 Thread Sarah Newman
On 03/17/2014 10:14 AM, George Dunlap wrote: On 03/17/2014 05:05 PM, Jan Beulich wrote: On 17.03.14 at 17:55, H. Peter Anvin h...@zytor.com wrote: So if this interface wasn't an accident it was active negligence and incompetence. I don't think so - while it (as we now see) disallows certain

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-18 Thread H. Peter Anvin
On 03/18/2014 11:17 AM, Sarah Newman wrote: Should or has there been a review of the current xen PVABI to look for any other such deviations? It would be a very good thing to do. First of all, the PVABI needs to be **documented** because without that there is no hope. I would like to

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-17 Thread George Dunlap
On Mon, Mar 17, 2014 at 3:33 AM, H. Peter Anvin h...@zytor.com wrote: No, the right thing is to unf*ck the Xen braindamage and use eagerfpu as a workaround for the legacy hypervisor versions. The interface wasn't an accident. In the most common case you'll want to clear the bit anyway. In PV

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-17 Thread David Vrabel
On 17/03/14 03:43, H. Peter Anvin wrote: On 03/16/2014 08:35 PM, Sarah Newman wrote: Can you please review my patch first? It's only enabled when absolutely required. It doesn't help. It means you're running on Xen, and you will have processes subjected to random SIGKILL because they

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-17 Thread H. Peter Anvin
On 03/17/2014 05:19 AM, George Dunlap wrote: On Mon, Mar 17, 2014 at 3:33 AM, H. Peter Anvin h...@zytor.com wrote: No, the right thing is to unf*ck the Xen braindamage and use eagerfpu as a workaround for the legacy hypervisor versions. The interface wasn't an accident. In the most common

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-17 Thread Jan Beulich
On 17.03.14 at 17:55, H. Peter Anvin h...@zytor.com wrote: On 03/17/2014 05:19 AM, George Dunlap wrote: On Mon, Mar 17, 2014 at 3:33 AM, H. Peter Anvin h...@zytor.com wrote: No, the right thing is to unf*ck the Xen braindamage and use eagerfpu as a workaround for the legacy hypervisor

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-17 Thread H. Peter Anvin
On 03/17/2014 10:05 AM, Jan Beulich wrote: I don't think so - while it (as we now see) disallows certain things inside the guest, back at the time when this was designed there was no sign of any sort of allocation/scheduling being done inside the #NM handler. And furthermore, a PV

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-17 Thread George Dunlap
On 03/17/2014 05:05 PM, Jan Beulich wrote: On 17.03.14 at 17:55, H. Peter Anvin h...@zytor.com wrote: On 03/17/2014 05:19 AM, George Dunlap wrote: On Mon, Mar 17, 2014 at 3:33 AM, H. Peter Anvin h...@zytor.com wrote: No, the right thing is to unf*ck the Xen braindamage and use eagerfpu as a

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-16 Thread Sarah Newman
Can you please review my patch first? It's only enabled when absolutely required. On 03/16/2014 08:33 PM, H. Peter Anvin wrote: No, the right thing is to unf*ck the Xen braindamage and use eagerfpu as a workaround for the legacy hypervisor versions. GFP_ATOMIC - SIGKILL is definitely a

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-16 Thread H. Peter Anvin
On 03/16/2014 08:35 PM, Sarah Newman wrote: Can you please review my patch first? It's only enabled when absolutely required. It doesn't help. It means you're running on Xen, and you will have processes subjected to random SIGKILL because they happen to touch the FPU when the atomic pool is

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-16 Thread Sarah Newman
On 03/16/2014 08:43 PM, H. Peter Anvin wrote: On 03/16/2014 08:35 PM, Sarah Newman wrote: Can you please review my patch first? It's only enabled when absolutely required. It doesn't help. It means you're running on Xen, and you will have processes subjected to random SIGKILL because

Re: [Xen-devel] [PATCHv1] x86: don't schedule when handling #NM exception

2014-03-16 Thread H. Peter Anvin
On 03/16/2014 09:12 PM, Sarah Newman wrote: Unconditional eager allocation works. Can xen users count on this being included and applied to the stable kernels? I don't know. If we state that it is a bug fix for Xen it might be possible, but it would be up to Greg (Cc:'d) and the rest of