Merging upstream version 6.7.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 327 insertions, 0 deletions

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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_meminfo 5 2023-08-15 "Linux man-pages 6.7"
+.SH NAME
+/proc/meminfo \- memory usage
+.SH DESCRIPTION
+.TP
+.I /proc/meminfo
+This file reports statistics about memory usage on the system.
+It is used by
+.BR free (1)
+to report the amount of free and used memory (both physical and swap)
+on the system as well as the shared memory and buffers used by the
+kernel.
+Each line of the file consists of a parameter name, followed by a colon,
+the value of the parameter, and an option unit of measurement (e.g., "kB").
+The list below describes the parameter names and
+the format specifier required to read the field value.
+Except as noted below,
+all of the fields have been present since at least Linux 2.6.0.
+Some fields are displayed only if the kernel was configured
+with various options; those dependencies are noted in the list.
+.RS
+.TP
+.IR MemTotal " %lu"
+Total usable RAM (i.e., physical RAM minus a few reserved
+bits and the kernel binary code).
+.TP
+.IR MemFree " %lu"
+The sum of
+.IR LowFree + HighFree .
+.TP
+.IR MemAvailable " %lu (since Linux 3.14)"
+An estimate of how much memory is available for starting new
+applications, without swapping.
+.TP
+.IR Buffers " %lu"
+Relatively temporary storage for raw disk blocks that
+shouldn't get tremendously large (20 MB or so).
+.TP
+.IR Cached " %lu"
+In-memory cache for files read from the disk (the page cache).
+Doesn't include
+.IR SwapCached .
+.TP
+.IR SwapCached " %lu"
+Memory that once was swapped out, is swapped back in but
+still also is in the swap file.
+(If memory pressure is high, these pages
+don't need to be swapped out again because they are already
+in the swap file.
+This saves I/O.)
+.TP
+.IR Active " %lu"
+Memory that has been used more recently and usually not
+reclaimed unless absolutely necessary.
+.TP
+.IR Inactive " %lu"
+Memory which has been less recently used.
+It is more eligible to be reclaimed for other purposes.
+.TP
+.IR Active(anon) " %lu (since Linux 2.6.28)"
+[To be documented.]
+.TP
+.IR Inactive(anon) " %lu (since Linux 2.6.28)"
+[To be documented.]
+.TP
+.IR Active(file) " %lu (since Linux 2.6.28)"
+[To be documented.]
+.TP
+.IR Inactive(file) " %lu (since Linux 2.6.28)"
+[To be documented.]
+.TP
+.IR Unevictable " %lu (since Linux 2.6.28)"
+(From Linux 2.6.28 to Linux 2.6.30,
+\fBCONFIG_UNEVICTABLE_LRU\fP was required.)
+[To be documented.]
+.TP
+.IR Mlocked " %lu (since Linux 2.6.28)"
+(From Linux 2.6.28 to Linux 2.6.30,
+\fBCONFIG_UNEVICTABLE_LRU\fP was required.)
+[To be documented.]
+.TP
+.IR HighTotal " %lu"
+(Starting with Linux 2.6.19, \fBCONFIG_HIGHMEM\fP is required.)
+Total amount of highmem.
+Highmem is all memory above \[ti]860 MB of physical memory.
+Highmem areas are for use by user-space programs,
+or for the page cache.
+The kernel must use tricks to access
+this memory, making it slower to access than lowmem.
+.TP
+.IR HighFree " %lu"
+(Starting with Linux 2.6.19, \fBCONFIG_HIGHMEM\fP is required.)
+Amount of free highmem.
+.TP
+.IR LowTotal " %lu"
+(Starting with Linux 2.6.19, \fBCONFIG_HIGHMEM\fP is required.)
+Total amount of lowmem.
+Lowmem is memory which can be used for everything that
+highmem can be used for, but it is also available for the
+kernel's use for its own data structures.
+Among many other things,
+it is where everything from
+.I Slab
+is allocated.
+Bad things happen when you're out of lowmem.
+.TP
+.IR LowFree " %lu"
+(Starting with Linux 2.6.19, \fBCONFIG_HIGHMEM\fP is required.)
+Amount of free lowmem.
+.TP
+.IR MmapCopy " %lu (since Linux 2.6.29)"
+.RB ( CONFIG_MMU
+is required.)
+[To be documented.]
+.TP
+.IR SwapTotal " %lu"
+Total amount of swap space available.
+.TP
+.IR SwapFree " %lu"
+Amount of swap space that is currently unused.
+.TP
+.IR Dirty " %lu"
+Memory which is waiting to get written back to the disk.
+.TP
+.IR Writeback " %lu"
+Memory which is actively being written back to the disk.
+.TP
+.IR AnonPages " %lu (since Linux 2.6.18)"
+Non-file backed pages mapped into user-space page tables.
+.TP
+.IR Mapped " %lu"
+Files which have been mapped into memory (with
+.BR mmap (2)),
+such as libraries.
+.TP
+.IR Shmem " %lu (since Linux 2.6.32)"
+Amount of memory consumed in
+.BR tmpfs (5)
+filesystems.
+.TP
+.IR KReclaimable " %lu (since Linux 4.20)"
+Kernel allocations that the kernel will attempt to reclaim
+under memory pressure.
+Includes
+.I SReclaimable
+(below), and other direct allocations with a shrinker.
+.TP
+.IR Slab " %lu"
+In-kernel data structures cache.
+(See
+.BR slabinfo (5).)
+.TP
+.IR SReclaimable " %lu (since Linux 2.6.19)"
+Part of
+.IR Slab ,
+that might be reclaimed, such as caches.
+.TP
+.IR SUnreclaim " %lu (since Linux 2.6.19)"
+Part of
+.IR Slab ,
+that cannot be reclaimed on memory pressure.
+.TP
+.IR KernelStack " %lu (since Linux 2.6.32)"
+Amount of memory allocated to kernel stacks.
+.TP
+.IR PageTables " %lu (since Linux 2.6.18)"
+Amount of memory dedicated to the lowest level of page tables.
+.TP
+.IR Quicklists " %lu (since Linux 2.6.27)"
+(\fBCONFIG_QUICKLIST\fP is required.)
+[To be documented.]
+.TP
+.IR NFS_Unstable " %lu (since Linux 2.6.18)"
+NFS pages sent to the server, but not yet committed to stable storage.
+.TP
+.IR Bounce " %lu (since Linux 2.6.18)"
+Memory used for block device "bounce buffers".
+.TP
+.IR WritebackTmp " %lu (since Linux 2.6.26)"
+Memory used by FUSE for temporary writeback buffers.
+.TP
+.IR CommitLimit " %lu (since Linux 2.6.10)"
+This is the total amount of memory currently available to
+be allocated on the system, expressed in kilobytes.
+This limit is adhered to
+only if strict overcommit accounting is enabled (mode 2 in
+.IR /proc/sys/vm/overcommit_memory ).
+The limit is calculated according to the formula described under
+.IR /proc/sys/vm/overcommit_memory .
+For further details, see the kernel source file
+.IR Documentation/vm/overcommit\-accounting.rst .
+.TP
+.IR Committed_AS " %lu"
+The amount of memory presently allocated on the system.
+The committed memory is a sum of all of the memory which
+has been allocated by processes, even if it has not been
+"used" by them as of yet.
+A process which allocates 1 GB of memory (using
+.BR malloc (3)
+or similar), but touches only 300 MB of that memory will show up
+as using only 300 MB of memory even if it has the address space
+allocated for the entire 1 GB.
+.IP
+This 1 GB is memory which has been "committed" to by the VM
+and can be used at any time by the allocating application.
+With strict overcommit enabled on the system (mode 2 in
+.IR /proc/sys/vm/overcommit_memory ),
+allocations which would exceed the
+.I CommitLimit
+will not be permitted.
+This is useful if one needs to guarantee that processes will not
+fail due to lack of memory once that memory has been successfully allocated.
+.TP
+.IR VmallocTotal " %lu"
+Total size of vmalloc memory area.
+.TP
+.IR VmallocUsed " %lu"
+Amount of vmalloc area which is used.
+Since Linux 4.4,
+.\" commit a5ad88ce8c7fae7ddc72ee49a11a75aa837788e0
+this field is no longer calculated, and is hard coded as 0.
+See
+.IR /proc/vmallocinfo .
+.TP
+.IR VmallocChunk " %lu"
+Largest contiguous block of vmalloc area which is free.
+Since Linux 4.4,
+.\" commit a5ad88ce8c7fae7ddc72ee49a11a75aa837788e0
+this field is no longer calculated and is hard coded as 0.
+See
+.IR /proc/vmallocinfo .
+.TP
+.IR HardwareCorrupted " %lu (since Linux 2.6.32)"
+(\fBCONFIG_MEMORY_FAILURE\fP is required.)
+[To be documented.]
+.TP
+.IR LazyFree " %lu (since Linux 4.12)"
+Shows the amount of memory marked by
+.BR madvise (2)
+.BR MADV_FREE .
+.TP
+.IR AnonHugePages " %lu (since Linux 2.6.38)"
+(\fBCONFIG_TRANSPARENT_HUGEPAGE\fP is required.)
+Non-file backed huge pages mapped into user-space page tables.
+.TP
+.IR ShmemHugePages " %lu (since Linux 4.8)"
+(\fBCONFIG_TRANSPARENT_HUGEPAGE\fP is required.)
+Memory used by shared memory (shmem) and
+.BR tmpfs (5)
+allocated with huge pages.
+.TP
+.IR ShmemPmdMapped " %lu (since Linux 4.8)"
+(\fBCONFIG_TRANSPARENT_HUGEPAGE\fP is required.)
+Shared memory mapped into user space with huge pages.
+.TP
+.IR CmaTotal " %lu (since Linux 3.1)"
+Total CMA (Contiguous Memory Allocator) pages.
+(\fBCONFIG_CMA\fP is required.)
+.TP
+.IR CmaFree " %lu (since Linux 3.1)"
+Free CMA (Contiguous Memory Allocator) pages.
+(\fBCONFIG_CMA\fP is required.)
+.TP
+.IR HugePages_Total " %lu"
+(\fBCONFIG_HUGETLB_PAGE\fP is required.)
+The size of the pool of huge pages.
+.TP
+.IR HugePages_Free " %lu"
+(\fBCONFIG_HUGETLB_PAGE\fP is required.)
+The number of huge pages in the pool that are not yet allocated.
+.TP
+.IR HugePages_Rsvd " %lu (since Linux 2.6.17)"
+(\fBCONFIG_HUGETLB_PAGE\fP is required.)
+This is the number of huge pages for
+which a commitment to allocate from the pool has been made,
+but no allocation has yet been made.
+These reserved huge pages
+guarantee that an application will be able to allocate a
+huge page from the pool of huge pages at fault time.
+.TP
+.IR HugePages_Surp " %lu (since Linux 2.6.24)"
+(\fBCONFIG_HUGETLB_PAGE\fP is required.)
+This is the number of huge pages in
+the pool above the value in
+.IR /proc/sys/vm/nr_hugepages .
+The maximum number of surplus huge pages is controlled by
+.IR /proc/sys/vm/nr_overcommit_hugepages .
+.TP
+.IR Hugepagesize " %lu"
+(\fBCONFIG_HUGETLB_PAGE\fP is required.)
+The size of huge pages.
+.TP
+.IR DirectMap4k " %lu (since Linux 2.6.27)"
+Number of bytes of RAM linearly mapped by kernel in 4 kB pages.
+(x86.)
+.TP
+.IR DirectMap4M " %lu (since Linux 2.6.27)"
+Number of bytes of RAM linearly mapped by kernel in 4 MB pages.
+(x86 with
+.B CONFIG_X86_64
+or
+.B CONFIG_X86_PAE
+enabled.)
+.TP
+.IR DirectMap2M " %lu (since Linux 2.6.27)"
+Number of bytes of RAM linearly mapped by kernel in 2 MB pages.
+(x86 with neither
+.B CONFIG_X86_64
+nor
+.B CONFIG_X86_PAE
+enabled.)
+.TP
+.IR DirectMap1G " %lu (since Linux 2.6.27)"
+(x86 with
+.B CONFIG_X86_64
+and
+.B CONFIG_X86_DIRECT_GBPAGES
+enabled.)
+.RE
+.SH SEE ALSO
+.BR proc (5)