Bug 461038

Summary: el4u5 pv guest user coredump crashing system
Product: Red Hat Enterprise Linux 4 Reporter: Greg Marsden <greg.marsden>
Component: kernel-xenAssignee: Oleg Nesterov <onestero>
Status: CLOSED ERRATA QA Contact: Chao Ye <cye>
Severity: medium Docs Contact:
Priority: medium    
Version: 4.9CC: clalance, cwyse, guru.anbalagane, herbert.van.den.bergh, keshav.sharma, mgahagan, onestero, qcai, sghosh, spurrier, tao, tina.yang, vfalico, xen-maint
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2011-02-16 16:02:28 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:

Description Greg Marsden 2008-09-03 15:58:46 UTC 
The system panicked during core dumping a faulting process.  The cause was
a wrong vsyscall page pointer from elf_core_dump for the el4u5 32bit pv
guest.  This patch resolves:

--- linux-2.6.9/include/asm-i386/elf.h.orig     2008-05-01 17:31:41.000000000
-0700
+++ linux-2.6.9/include/asm-i386/elf.h  2008-05-01 17:32:06.000000000 -0700
@@ -141,11 +141,7 @@
#define VSYSCALL_ENTRY (VSYSCALL_BASE + VSYSCALL_OFFSET)
 
/* kernel-internal fixmap address: */
-#ifdef CONFIG_XEN
-#define __VSYSCALL_BASE        (PAGE_OFFSET - 2*PAGE_SIZE)
-#else
 #define __VSYSCALL_BASE        (__fix_to_virt(FIX_VSYSCALL))
-#endif
 #define __VSYSCALL_EHDR        ((const struct elfhdr *) __VSYSCALL_BASE)
Comment 1 Tina Yang 2008-09-03 18:34:39 UTC 
This is a workaround, minimum fix.  The problem is the page the __VSYSCALL_BASE points to in el4u5 XEN case doesn't seem to be ever set up.  It seems to me the intended logic is only half-implemented.  I did see however in el5, this part of the dump has been completely eliminated.  So, whichever is appropriate.
Comment 2 Guy Streeter 2008-12-03 18:43:00 UTC 
I have a customer report of this same problem, solved by this patch.
Comment 4 Veaceslav Falico 2009-03-25 18:02:11 UTC 
I also have a customer report of this same problem, solved by this patch. Customer asks for hotfix.
Comment 8 Chris Lalancette 2009-04-10 09:13:34 UTC 
Can someone who is affected by this bug please let me know what the exact problem is, and if there is a way to reproduce it?  The patch in Comment #1 looks sane enough, but I don't have a good idea of the real problem, and I would like to verify myself if a reproducer is available.

Thanks,
Chris Lalancette
Comment 11 Oleg Nesterov 2009-05-26 18:54:12 UTC 
Patch:

http://post-office.corp.redhat.com/archives/rhkernel-list/2009-May/msg00819.html
Comment 13 Vivek Goyal 2009-06-03 13:56:31 UTC 
Committed in 89.2.EL
Comment 15 Paolo Bonzini 2010-10-06 14:20:03 UTC 
*** Bug 594531 has been marked as a duplicate of this bug. ***
Comment 17 Chao Ye 2011-01-12 09:59:23 UTC 
Verified with -95.EL:
=========================================
I'm still alive, will sleep now
runtest.sh: line 20: 10904 Segmentation fault      (core dumped) sh PCD.sh
Success to core dump of process 10904

$ cat PCD.sh 
#!/bin/sh

while true
do
    echo "I'm still alive, will sleep now"
    sleep 60
done

$ cat runtest.sh 
#!/bin/sh

ulimit -c unlimited
sh PCD.sh &
ID=`ps aux | grep PCD | sed '/grep/d' | awk '{ print $2 }'`
kill -s 11 $ID
if [ -f core.$ID ]; then
    echo "Success to core dump of process $ID"
    rm -f core.$ID
else
    echo "Failed  to core dump of process $ID"
fi

Change status to VERIFIED
Comment 18 errata-xmlrpc 2011-02-16 16:02:28 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 therefore 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-2011-0263.html