From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Tian, Kevin" Subject: RE: RE: Kernel BUG at arch/x86/mm/tlb.c:61 Date: Tue, 26 Apr 2011 13:55:50 +0800 Message-ID: <625BA99ED14B2D499DC4E29D8138F1505C7F2C518E@shsmsx502.ccr.corp.intel.com> References: , , , , , , , <4DA3438A.6070503@goop.org>, , , <20110412100000.GA15647@dumpdata.com>, , , , , , <4DA8B715.9080508@goop.org>, , ,

Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1962481668==" Return-path: In-Reply-To: Content-Language: en-US List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: MaoXiaoyun , "jeremy@goop.org" Cc: xen devel , "giamteckchoon@gmail.com" , "konrad.wilk@oracle.com" List-Id: xen-devel@lists.xenproject.org --===============1962481668== Content-Language: en-US Content-Type: multipart/alternative; boundary="_000_625BA99ED14B2D499DC4E29D8138F1505C7F2C518Eshsmsx502ccrc_" --_000_625BA99ED14B2D499DC4E29D8138F1505C7F2C518Eshsmsx502ccrc_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable the race window is always there, but whether it will be triggered is not de= termined. It's possible that you never met this bug on 2.6.31.x now, but it= doesn't mean you won't meet it in long run in the future. :) Thanks Kevin From: xen-devel-bounces@lists.xensource.com [mailto:xen-devel-bounces@lists= .xensource.com] On Behalf Of MaoXiaoyun Sent: Monday, April 25, 2011 11:05 PM To: jeremy@goop.org Cc: xen devel; giamteckchoon@gmail.com; konrad.wilk@oracle.com Subject: [Xen-devel] RE: Kernel BUG at arch/x86/mm/tlb.c:61 Please ignore my last two mails, I just learnt that Current is meanless in = irq context. Just come up one whole assumption: In my opinion: 1) CPU running in switch_mm has the possiblity of receiving IPI message and= enter interrupt 2) Before revert that patch, not matter the if statement is true or not, th= e cpu_tlbstate.state could be changed to TLBSTATE_OK, right before enter irq routhine 3) Since the cpu_tlbstate is per CPU variable, before calling leave_mm(), t= est cpu_tlbstate.state in drop_other_mm_ref is feasible and nessary 4) If I am right, strange thing is the code of 2.6.32.36 is same as 2.6.31.= x, which we never met tlb bug before. any comments? Many thanks. --_000_625BA99ED14B2D499DC4E29D8138F1505C7F2C518Eshsmsx502ccrc_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

the race window is always there, but whether it will be triggered is no= t determined. It’s possible that you never met this bug on 2.6.31.x n= ow, but it doesn’t mean you won’t meet it in long run in the fu= ture. J

Thanks

Kevin

From: xen-devel-bounces@lists.xensourc= e.com [mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of Ma= oXiaoyun
Sent: Monday, April 25, 2011 11:05 PM
To: jere= my@goop.org
Cc: xen devel; giamteckchoon@gmail.com; konrad.wilk@o= racle.com
Subject: [Xen-devel] RE: Kernel BUG at arch/x86/mm/tlb.= c:61

Please ignore my last two mails, I just learnt that Current is mean= less in irq context.

Just come up one whole assumption:
&nb= sp;
In my opinion:

1) CPU running in switch_mm has the poss= iblity of receiving IPI message and enter interrupt
2) Before revert tha= t patch, not matter the if statement is true or not, the cpu_tlbstate.state=
could be changed to TLBSTATE_OK, right before enter irq routhine
3) = Since the cpu_tlbstate is per CPU variable, before calling leave_mm(),= test cpu_tlbstate.state
in drop_other_mm_ref is feasible and nessary4) If I am right, strange thing is the code of 2.6.32.36 is same as 2.6.31= .x, which we never met tlb bug before.

any comments?
=
Many thanks.

= --_000_625BA99ED14B2D499DC4E29D8138F1505C7F2C518Eshsmsx502ccrc_-- --===============1962481668== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel --===============1962481668==--