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Bug 236662 - Sun 32-bit JVM unable to allocate large pages memory greater than 2147483648 bytes
Summary: Sun 32-bit JVM unable to allocate large pages memory greater than 2147483648 ...
Alias: None
Product: Red Hat Enterprise Linux 4
Classification: Red Hat
Component: kernel
Version: 4.3
Hardware: x86_64
OS: Linux
Target Milestone: ---
: ---
Assignee: Larry Woodman
QA Contact: Martin Jenner
Depends On:
TreeView+ depends on / blocked
Reported: 2007-04-17 01:33 UTC by Shrinivas Joshi
Modified: 2007-11-17 01:14 UTC (History)
5 users (show)

Fixed In Version: RHBA-2007-0791
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2007-11-15 16:25:10 UTC
Target Upstream Version:

Attachments (Terms of Use)

System ID Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2007:0791 normal SHIPPED_LIVE Updated kernel packages available for Red Hat Enterprise Linux 4 Update 6 2007-11-14 18:25:55 UTC

Description Shrinivas Joshi 2007-04-17 01:33:26 UTC
Description of problem:
Sun JVM exits with error:
Java HotSpot(TM) Server VM warning: Failed to reserve shared memory (errno = 22)
when it tries to allocate heap > 1980M and is configured to use large page
support. The OS trace generated using strace command shows that the cause of the
problem is call to shmget syscall.

Version-Release number of selected component (if applicable):
Dual-core AMD Opteron 870 4 processor system (8 cores). 8G system memory.
The problem is probably reproducible on other x86_64 systems with memory greater
than 4G
RHEL 4 update 3, 2.6.9-34.ELsmp, x86_64 
Sun 32-bit JVM 1.5 build 6

How reproducible:
Try to initialize JVM process on above mentioned system configuration.

Steps to Reproduce:
1. Install Sun JVM 32-bit 1.5 build 6 or above
2. Configure the system to enable large pages after OS reboot (to avoid
 a. echo 8589934591 > /proc/sys/kernel/shmmax //All 8G shareable
 b. echo 3072 > /proc/sys/vm/nr_hugepages //6G for large pages of 2048K each
 c. verify whether large pages are allocated using cat /proc/meminfo;
HugePagesTotal and HugePagesFree should be equal to 3072
3. Start installed JVM process using:
<java-install-path>/bin/java -Xms1984M -Xmx1984M -XX:+UseLargePages -version
Problem is in fact reproducible for any -Xms and -Xmx values greater than 1980M,
however make sure that the requested memory aligns to 2M pages (1980M, 1982M,
1984M ...)
Actual results:
JVM exits with error:
Java HotSpot(TM) Server VM warning: Failed to reserve shared memory (errno = 22)

Expected results:
JVM should successfully allocate requested memory using large pages support

Additional info: It appears that the call to shmget fails due to max permissible
value of its second parameter "size" in 32-bit compatibility mode. However even
in 32-bit compatibility mode the "size" parameter which is of type unsigned long
should allow values <= 2^32 (4G) rather than 2^31 (2G, signed long max value)

Comment 1 Jakub Jelinek 2007-04-17 02:37:41 UTC
This has nothing to do with compat-libs (which have been only shipped in RHEL2.1
and never since then).

Comment 2 Larry Woodman 2007-04-17 17:16:54 UTC
I doubt we can change this without breaking the ABI.  Even worse, this is the
syscall interface so changing this will break user applications.  Basically
32-bit compatibility mode limits system V shared memory regions to 231-1 because
sys32_ipc() uses ints for args.

asmlinkage long
sys32_ipc(u32 call, int first, int second, int third,
               compat_uptr_t ptr, u32 fifth)
       int version;
       version = call >> 16; /* hack for backward compatibility */
       call &= 0xffff;
       switch (call) {
             case SHMGET:
               return sys_shmget(first, second, third);

Larry Woodman

Comment 3 Larry Woodman 2007-04-18 15:40:35 UTC
I made this upstream change to RHEL4 and it seems to fix the problem:

--- linux-2.6.9/arch/x86_64/ia32/ipc32.c.orig
+++ linux-2.6.9/arch/x86_64/ia32/ipc32.c
@@ -49,7 +49,7 @@ sys32_ipc(u32 call, int first, int secon
              case SHMDT:
                return sys_shmdt(compat_ptr(ptr));
              case SHMGET:
-               return sys_shmget(first, second, third);
+               return sys_shmget(first, (unsigned)second, third);
              case SHMCTL:
                return compat_sys_shmctl(first, second, compat_ptr(ptr));

I built a new kernel located here can you try it out and let me know if its OK
with you???


Larry Woodman

Comment 4 Bhavna Sarathy 2007-05-15 13:12:33 UTC
This fix results in a 5-10% increase improvement in SPECjAppServer benchmark and
AMD would like customers to have this fix before RHEL4.6 which will release in
Oct 24.  AMD would like to request a kernel errata with this fix made available
to customers.  The actual performance gain will depend on the SUT configuration
and with injection rates of > 450 the performance will improve considerably.

Comment 5 Russell Doty 2007-07-10 21:52:10 UTC
Peter M. indicates that it was ACK'd by Rik and Alan on 4/19/2007. Larry Woodman
says he will make sure Jason commits the patch, he does know about it.

Comment 6 RHEL Product and Program Management 2007-07-10 21:54:58 UTC
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update

Comment 9 Jason Baron 2007-07-31 20:25:32 UTC
committed in stream U6 build 55.6. A test kernel with this patch is available

Comment 13 errata-xmlrpc 2007-11-15 16:25:10 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.

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