page allocation failure. order: 2

  • 7002803
  • 24-Mar-2009
  • 27-Apr-2012

Environment

Novell SUSE Linux
Novell SUSE Linux Enterprise Server 10 Service Pack 2
Novell SUSE Linux Enterprise Server 9 Service Pack 4
Novell SUSE Linux Enterprise Desktop 10 Service Pack 2
Novell Open Enterprise Server 2 (OES 2)
Novell Open Enterprise Server (Linux based)

Situation

A message appears in /var/log/messages saying something similar to

swapper: page allocation failure. order:2, mode:0x20

followed by a stack trace

Resolution

The message looks like a crash, because of the stack trace, but it isn't. It is an informational message which may be safely ignored.


Additional Information

When a kernel thread requests memory internally, it specifies an"order" of allocation. This is a power of 2 indicating how many contiguous pages are requested. An allocation of order 2 is then two to the second = four contiguous pages. If the virtual memory subsystem can't find a block of four contiguous pages, it will return an allocation failure.

The thread requesting the memory then has the option of either terminating with an error, or requesting multiple smaller blocks instead. Normally, the latter happens.

This is normally transparent to the user, most memory allocation requests never print this message, but in some cases the calling thread requests that the system log a message in case of failure. But it is purely for informational purposes, and does not by itself indicate an error condition

Only if an allocation of order 0 (a single page) fails, or if the failed allocation is followed by an error message from the thread requesting the memory is the message a reason for concern.

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