1MIGRATE_PAGES(2)           Linux Programmer's Manual          MIGRATE_PAGES(2)
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NAME

6       migrate_pages - move all pages in a process to another set of nodes
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SYNOPSIS

9       #include <numaif.h>
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11       long migrate_pages(int pid, unsigned long maxnode,
12                          const unsigned long *old_nodes,
13                          const unsigned long *new_nodes);
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15       Link with -lnuma.
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DESCRIPTION

18       migrate_pages()  attempts to move all pages of the process pid that are
19       in memory nodes old_nodes to the memory nodes in new_nodes.  Pages  not
20       located  in any node in old_nodes will not be migrated.  As far as pos‐
21       sible, the kernel maintains the relative topology  relationship  inside
22       old_nodes during the migration to new_nodes.
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24       The old_nodes and new_nodes arguments are pointers to bit masks of node
25       numbers, with up to maxnode bits in each mask.  These masks  are  main‐
26       tained  as  arrays of unsigned long integers (in the last long integer,
27       the bits beyond those specified by maxnode are ignored).   The  maxnode
28       argument  is  the maximum node number in the bit mask plus one (this is
29       the same as in mbind(2), but different from select(2)).
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31       The pid argument is the ID of the process whose pages are to be  moved.
32       To  move  pages  in  another  process,  the  caller  must be privileged
33       (CAP_SYS_NICE) or the real or effective user ID of the calling  process
34       must match the real or saved-set user ID of the target process.  If pid
35       is 0, then migrate_pages() moves pages of the calling process.
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37       Pages shared with another process will be moved only if the  initiating
38       process has the CAP_SYS_NICE privilege.
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RETURN VALUE

41       On  success  migrate_pages() returns the number of pages that could not
42       be moved (i.e., a return of zero means that all pages were successfully
43       moved).  On error, it returns -1, and sets errno to indicate the error.
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ERRORS

46       EFAULT Part or all of the memory range specified by old_nodes/new_nodes
47              and maxnode points outside your accessible address space.
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49       EINVAL The value specified by maxnode exceeds a  kernel-imposed  limit.
50              Or,  old_nodes  or new_nodes specifies one or more node IDs that
51              are greater than the maximum supported node ID.  Or, none of the
52              node  IDs  specified by new_nodes are on-line and allowed by the
53              process's current cpuset context, or none of the specified nodes
54              contain memory.
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56       EPERM  Insufficient  privilege  (CAP_SYS_NICE)  to  move  pages  of the
57              process   specified   by   pid,   or   insufficient    privilege
58              (CAP_SYS_NICE) to access the specified target nodes.
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60       ESRCH  No process matching pid could be found.
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VERSIONS

63       The  migrate_pages()  system  call  first  appeared on Linux in version
64       2.6.16.
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CONFORMING TO

67       This system call is Linux-specific.
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NOTES

70       For information on library support, see numa(7).
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72       Use get_mempolicy(2) with the MPOL_F_MEMS_ALLOWED flag  to  obtain  the
73       set  of  nodes  that are allowed by the calling process's cpuset.  Note
74       that this information is subject to change at any  time  by  manual  or
75       automatic reconfiguration of the cpuset.
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77       Use  of  migrate_pages() may result in pages whose location (node) vio‐
78       lates the memory policy established for the  specified  addresses  (see
79       mbind(2))  and/or  the  specified process (see set_mempolicy(2)).  That
80       is, memory policy does not constrain  the  destination  nodes  used  by
81       migrate_pages().
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83       The  <numaif.h>  header  is  not  included  with  glibc,  but  requires
84       installing libnuma-devel or a similar package.
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SEE ALSO

87       get_mempolicy(2), mbind(2),  set_mempolicy(2),  numa(3),  numa_maps(5),
88       cpuset(7), numa(7), migratepages(8), numastat(8)
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90       Documentation/vm/page_migration.rst in the Linux kernel source tree
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COLOPHON

93       This  page  is  part of release 5.04 of the Linux man-pages project.  A
94       description of the project, information about reporting bugs,  and  the
95       latest     version     of     this    page,    can    be    found    at
96       https://www.kernel.org/doc/man-pages/.
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100Linux                             2019-03-06                  MIGRATE_PAGES(2)
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