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+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_buddyinfo 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/buddyinfo \- memory fragmentation
+.SH DESCRIPTION
+.TP
+.I /proc/buddyinfo
+This file contains information which is used for diagnosing memory
+fragmentation issues.
+Each line starts with the identification of the node and the name
+of the zone which together identify a memory region.
+This is then
+followed by the count of available chunks of a certain order in
+which these zones are split.
+The size in bytes of a certain order is given by the formula:
+.IP
+.in +4n
+.EX
+(2\[ha]order)\ *\ PAGE_SIZE
+.EE
+.in
+.IP
+The binary buddy allocator algorithm inside the kernel will split
+one chunk into two chunks of a smaller order (thus with half the
+size) or combine two contiguous chunks into one larger chunk of
+a higher order (thus with double the size) to satisfy allocation
+requests and to counter memory fragmentation.
+The order matches the column number, when starting to count at zero.
+.IP
+For example on an x86-64 system:
+.RS -12
+.EX
+Node 0, zone     DMA     1    1    1    0    2    1    1    0    1    1    3
+Node 0, zone   DMA32    65   47    4   81   52   28   13   10    5    1  404
+Node 0, zone  Normal   216   55  189  101   84   38   37   27    5    3  587
+.EE
+.RE
+.IP
+In this example, there is one node containing three zones and there
+are 11 different chunk sizes.
+If the page size is 4 kilobytes, then the first zone called
+.I DMA
+(on x86 the first 16 megabyte of memory) has 1 chunk of 4 kilobytes
+(order 0) available and has 3 chunks of 4 megabytes (order 10) available.
+.IP
+If the memory is heavily fragmented, the counters for higher
+order chunks will be zero and allocation of large contiguous areas
+will fail.
+.IP
+Further information about the zones can be found in
+.IR /proc/zoneinfo .
+.SH SEE ALSO
+.BR proc (5)