Bug 245983

Summary: HugePages_Rsvd wraps hugely negative
Product: [Community] Bugzilla Reporter: IBM Mirproxy <mirproxy>
Component: TestAssignee: PnT DevOps Devs <hss-ied-bugs>
Status: CLOSED NOTABUG QA Contact:
Severity: medium Docs Contact:
Priority: low    
Version: 2.8   
Target Milestone: ---   
Target Release: ---   
Hardware: other   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2007-09-04 16:25:08 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:
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Description Flags
[PATCH]_hugetlb:_fix_absurd_HugePages_Rsvd none

Description IBM Mirproxy 2007-06-27 19:27:00 UTC 
=Comment: #0=================================================
ADAM G. LITKE <litke.com> - 2006-11-29 10:31 EDT
---Problem Description---
If you truncated an mmap'ed hugetlbfs file, then faulted on the truncated area,
/proc/meminfo's HugePages_Rsvd wrapped hugely "negative".
 
Contact Information = Adam Litke/<a href="agl.com">agl.com</a>
 
---Additional Hardware Info---
hugetlbfs mounted
10 huge pages allocated
 
---uname output---
Linux beavis.ltc.austin.ibm.com 2.6.18-1.2747.el5 #1 SMP Wed Aug 30 18:29:48 EDT
2006 ppc64 ppc64 ppc64 GNU/Linux

---Steps to Reproduce---
The latest libhugetlbfs development snapshots have a test case for this bug.

1. Download libhugetlbfs
<a
href="http://libhugetlbfs.ozlabs.org/snapshots/libhugetlbfs-dev-20061108.tar.gz">http://libhugetlbfs.ozlabs.org/snapshots/libhugetlbfs-dev-20061108.tar.gz</a>
2. Mount hugetlbfs and allocate some huge pages (try 10)
3. Unpack and build libhugetlbfs
4. Run tests/obj32/truncate_sigbus_versus_oom <nr free hugepages>

The test should FAIL and an examination of /proc/meminfo should show an
extremely large value for HugePages_Rsvd.
=Comment: #1=================================================
ADAM G. LITKE <litke.com> - 2006-11-29 10:33 EDT
<a href="attachment.cgi?id=22577" class="" title="[PATCH] hugetlb: fix absurd
HugePages_Rsvd">Created an attachment (id=22577)</a> [<a
href="attachment.cgi?id=22577&action=edit">edit</a>]
[PATCH] hugetlb: fix absurd HugePages_Rsvd

The attached patch was accepted upstream (see below) and resolves the issue. 
Modified to apply cleanly to the 2.6.18-1.2747.el5 kernel.

commit ebed4bfc8da8df5b6b0bc4a5064a949f04683509
Author: Hugh Dickins <<a href="hugh">hugh</a>>
Date:	Sat Oct 28 10:38:43 2006 -0700

    [PATCH] hugetlb: fix absurd HugePages_Rsvd

    If you truncated an mmap'ed hugetlbfs file, then faulted on the truncated
    area, /proc/meminfo's HugePages_Rsvd wrapped hugely "negative".  Reinstate
my
    preliminary i_size check before attempting to allocate the page (though
this
    only fixes the most obvious case: more work will be needed here).

    Signed-off-by: Hugh Dickins <<a href="hugh">hugh</a>>
    Cc: Adam Litke <<a href="agl.com">agl.com</a>>
    Cc: David Gibson <<a href="david.id.au">david.id.au</a>>
    Cc: "Chen, Kenneth W" <<a href="kenneth.w.chen">kenneth.w.chen</a>>
    Signed-off-by: Andrew Morton <<a href="akpm">akpm</a>>
    Signed-off-by: Linus Torvalds <<a href="torvalds">torvalds</a>>
Comment 1 IBM Mirproxy 2007-06-27 19:27:13 UTC 
Created attachment 158045 [details]
[PATCH]_hugetlb:_fix_absurd_HugePages_Rsvd
Comment 2 IBM Mirproxy 2007-06-27 19:27:22 UTC 
------- Comment From tmello.com 2007-06-27 15:07 EDT-------
Some comment.