Bus error while allocating hugepages in domain 0

Bus error while allocating hugepages in domain 0

[Kaustubh Kabra]

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Hi,

My dom 0 is jeremy kernel 2.6.32.27 with 3.5 GB allocated memory. I tried
allocating 700 huge pages in domain 0 using-
]echo 700 > /proc/sys/vm/nr_hugepages

To verify -
]cat /proc/meminfo |grep Huge
HugePages_Total:     700
HugePages_Free:        0
HugePages_Rsvd:    18446744073709551019
HugePages_Surp:        0
Hugepagesize:       2048 kB

This memory information is not as per expectation.
Can anyone explain whether it has really allocated huge pages as calling
mmap with MAP_HUGETLB using

]addr = mmap((void *)0x0UL,600UL*1024*1024 , PROT_WRITE,MAP_PRIVATE |
MAP_ANONYMOUS | MAP_HUGETLB , 0, 0);

also results into a bus error.

]dmesg-
Process 4617(a.out) has RLIMIT_CORE set to 0
Aborting core

]strace-
--- SIGBUS (Bus error) @ 0 (0) ---
+++ killed by SIGBUS +++
Bus error

-- 
Kaustubh Kabra* <http://www.kaustubhwise.000a.biz>*

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Re: Bus error while allocating hugepages in domain 0

[Konrad Rzeszutek Wilk]

On Fri, Jan 28, 2011 at 02:07:52AM +0530, Kaustubh Kabra wrote:
> Hi,
> 
> My dom 0 is jeremy kernel 2.6.32.27 with 3.5 GB allocated memory. I tried
> allocating 700 huge pages in domain 0 using-
> ]echo 700 > /proc/sys/vm/nr_hugepages
> 
> To verify -
> ]cat /proc/meminfo |grep Huge
> HugePages_Total:     700
> HugePages_Free:        0
> HugePages_Rsvd:    18446744073709551019
> HugePages_Surp:        0
> Hugepagesize:       2048 kB
> 
> This memory information is not as per expectation.
> Can anyone explain whether it has really allocated huge pages as calling
> mmap with MAP_HUGETLB using

I think that is right. You did try this on baremetal and it worked right?

It looks as if we just haven't implemented this correctly, but I thought
Dave had it fixed at some point?


Ah wait.. http://lists.xensource.com/archives/html/xen-devel/2010-04/msg00971.html

it even is mentioned in
http://wiki.xensource.com/xenwiki/XenUpdate20100423

> 
> ]addr = mmap((void *)0x0UL,600UL*1024*1024 , PROT_WRITE,MAP_PRIVATE |
> MAP_ANONYMOUS | MAP_HUGETLB , 0, 0);
> 
> also results into a bus error.
> 
> ]dmesg-
> Process 4617(a.out) has RLIMIT_CORE set to 0
> Aborting core
> 
> ]strace-
> --- SIGBUS (Bus error) @ 0 (0) ---
> +++ killed by SIGBUS +++
> Bus error
> 
> -- 
> Kaustubh Kabra* <http://www.kaustubhwise.000a.biz>*

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> Xen-devel mailing list
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