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Bug 169294

Summary:	[RHEL3 U6] __copy_user/memcpy causes random kernel panic on IA-64 systems
Product:	Red Hat Enterprise Linux 3	Reporter:	Issue Tracker <tao>
Component:	kernel	Assignee:	Geoff Gustafson <grgustaf>
Status:	CLOSED ERRATA	QA Contact:	Brian Brock <bbrock>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	3.0	CC:	jburke, petrides, tao
Target Milestone:	---
Target Release:	---
Hardware:	ia64
OS:	Linux
Whiteboard:
Fixed In Version:	RHSA-2006-0144	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2006-03-15 16:42:54 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	168424

Description Issue Tracker 2005-09-26 17:50:38 UTC

Escalated to Bugzilla from IssueTracker

Comment 7 Gary Case 2005-11-22 22:42:33 UTC

Reposting the patch publicly. 

Excerpt from ChangeLog-2.6.14-rc1:

When copying data from user-space to kernel-space by __copy_user(),
a page_not_present fault sometimes occurs at vmalloced kernel address
because of VHPT pre-fetching.

Ignore the page_not_present fault in ia64_do_page_fault() before
jumping into exception handlers.

diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c

file:a949a83e0dccbb34531dea37145fee9ab3ea6895 ->
file:ee85e28e2ec5f05486b25265ce2a9568590ea7af
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -206,9 +206,6 @@ ia64_do_page_fault (unsigned long addres
               return;
       }

-       if (done_with_exception(regs))
-               return;
-
       /*
        * Since we have no vma's for region 5, we might get here even if the
address is
        * valid, due to the VHPT walker inserting a non present translation that
becomes
@@ -219,6 +216,9 @@ ia64_do_page_fault (unsigned long addres
       if (REGION_NUMBER(address) == 5 && mapped_kernel_page_is_present(address))
               return;

+       if (done_with_exception(regs))
+               return;
+
       /*
        * Oops. The kernel tried to access some bad page. We'll have to
terminate things
        * with extreme prejudice.

Comment 12 Ernie Petrides 2005-11-28 23:44:43 UTC

In answer to comment #10, the fix is queued for the next U7 build, which
will probably occur tomorrow night.

Comment 13 Ernie Petrides 2005-11-30 07:38:08 UTC

A fix for this problem has just been committed to the RHEL3 U7
patch pool this evening (in kernel version 2.4.21-37.12.EL).

Comment 17 Red Hat Bugzilla 2006-03-15 16:42:54 UTC

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2006-0144.html