page allocation failure. order: 2

This document (7002803) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 10 SP2
SUSE Linux Enterprise Desktop 10 SP2

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.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.