.\" SPDX-License-Identifier: Linux-man-pages-copyleft-2-para .\" .\" Copyright 2009 Intel Corporation .\" Author: Andi Kleen .\" Based on the move_pages manpage which was .\" This manpage is Copyright (C) 2006 Silicon Graphics, Inc. .\" Christoph Lameter .\" .TH migrate_pages 2 2024-05-02 "Linux man-pages 6.9.1" .SH NAME migrate_pages \- move all pages in a process to another set of nodes .SH LIBRARY NUMA (Non-Uniform Memory Access) policy library .RI ( libnuma ", " \-lnuma ) .SH SYNOPSIS .nf .B #include .P .BI "long migrate_pages(int " pid ", unsigned long " maxnode, .BI " const unsigned long *" old_nodes, .BI " const unsigned long *" new_nodes ); .fi .SH DESCRIPTION .BR migrate_pages () attempts to move all pages of the process .I pid that are in memory nodes .I old_nodes to the memory nodes in .IR new_nodes . Pages not located in any node in .I old_nodes will not be migrated. As far as possible, the kernel maintains the relative topology relationship inside .I old_nodes during the migration to .IR new_nodes . .P The .I old_nodes and .I new_nodes arguments are pointers to bit masks of node numbers, with up to .I maxnode bits in each mask. These masks are maintained as arrays of unsigned .I long integers (in the last .I long integer, the bits beyond those specified by .I maxnode are ignored). The .I maxnode argument is the maximum node number in the bit mask plus one (this is the same as in .BR mbind (2), but different from .BR select (2)). .P The .I pid argument is the ID of the process whose pages are to be moved. To move pages in another process, the caller must be privileged .RB ( CAP_SYS_NICE ) or the real or effective user ID of the calling process must match the real or saved-set user ID of the target process. If .I pid is 0, then .BR migrate_pages () moves pages of the calling process. .P Pages shared with another process will be moved only if the initiating process has the .B CAP_SYS_NICE privilege. .SH RETURN VALUE On success .BR migrate_pages () returns the number of pages that could not be moved (i.e., a return of zero means that all pages were successfully moved). On error, it returns \-1, and sets .I errno to indicate the error. .SH ERRORS .TP .B EFAULT Part or all of the memory range specified by .IR old_nodes / new_nodes and .I maxnode points outside your accessible address space. .TP .B EINVAL The value specified by .I maxnode exceeds a kernel-imposed limit. .\" As at 3.5, this limit is "a page worth of bits", e.g., .\" 8 * 4096 bits, assuming a 4kB page size. Or, .I old_nodes or .I new_nodes specifies one or more node IDs that are greater than the maximum supported node ID. Or, none of the node IDs specified by .I new_nodes are on-line and allowed by the process's current cpuset context, or none of the specified nodes contain memory. .TP .B EPERM Insufficient privilege .RB ( CAP_SYS_NICE ) to move pages of the process specified by .IR pid , or insufficient privilege .RB ( CAP_SYS_NICE ) to access the specified target nodes. .TP .B ESRCH No process matching .I pid could be found. .\" FIXME Document the other errors that can occur for migrate_pages() .SH STANDARDS Linux. .SH HISTORY Linux 2.6.16. .SH NOTES For information on library support, see .BR numa (7). .P Use .BR get_mempolicy (2) with the .B MPOL_F_MEMS_ALLOWED flag to obtain the set of nodes that are allowed by the calling process's cpuset. Note that this information is subject to change at any time by manual or automatic reconfiguration of the cpuset. .P Use of .BR migrate_pages () may result in pages whose location (node) violates the memory policy established for the specified addresses (see .BR mbind (2)) and/or the specified process (see .BR set_mempolicy (2)). That is, memory policy does not constrain the destination nodes used by .BR migrate_pages (). .P The .I header is not included with glibc, but requires installing .I libnuma\-devel or a similar package. .SH SEE ALSO .BR get_mempolicy (2), .BR mbind (2), .BR set_mempolicy (2), .BR numa (3), .BR numa_maps (5), .BR cpuset (7), .BR numa (7), .BR migratepages (8), .BR numastat (8) .P .I Documentation/vm/page_migration.rst in the Linux kernel source tree