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authorLinus Torvalds <torvalds@linux-foundation.org>2021-11-03 08:11:39 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-11-03 08:11:39 +0300
commit624ad333d49e136c54a342ce0009a05b439616be (patch)
tree199d58e6fdbc1273f43f6022e62256ccd4601a30 /Documentation/admin-guide
parent313b6ffc8e90173f1709b2f4bf9d30c4730a1dde (diff)
parent603bdf5d6c092eb05666decd84288dfda71eee90 (diff)
downloadlinux-624ad333d49e136c54a342ce0009a05b439616be.tar.xz
Merge tag 'docs-5.16' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet: "This is a relatively unexciting cycle for documentation. - Some small scripts/kerneldoc fixes - More Chinese translation work, but at a much reduced rate. - The tip-tree maintainer's handbook ...plus the usual array of build fixes, typo fixes, etc" * tag 'docs-5.16' of git://git.lwn.net/linux: (53 commits) kernel-doc: support DECLARE_PHY_INTERFACE_MASK() docs/zh_CN: add core-api xarray translation docs/zh_CN: add core-api assoc_array translation speakup: Fix typo in documentation "boo" -> "boot" docs: submitting-patches: make section about the Link: tag more explicit docs: deprecated.rst: Clarify open-coded arithmetic with literals scripts: documentation-file-ref-check: fix bpf selftests path scripts: documentation-file-ref-check: ignore hidden files coding-style.rst: trivial: fix location of driver model macros docs: f2fs: fix text alignment docs/zh_CN add PCI pci.rst translation docs/zh_CN add PCI index.rst translation docs: translations: zh_CN: memory-hotplug.rst: fix a typo docs: translations: zn_CN: irq-affinity.rst: add a missing extension block: add documentation for inflight scripts: kernel-doc: Ignore __alloc_size() attribute docs: pdfdocs: Adjust \headheight for fancyhdr docs: UML: user_mode_linux_howto_v2 edits docs: use the lore redirector everywhere docs: proc.rst: mountinfo: align columns ...
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/mm/pagemap.rst22
-rw-r--r--Documentation/admin-guide/spkguide.txt2
2 files changed, 23 insertions, 1 deletions
diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst
index fb578fbbb76c..4581527c07ae 100644
--- a/Documentation/admin-guide/mm/pagemap.rst
+++ b/Documentation/admin-guide/mm/pagemap.rst
@@ -196,6 +196,28 @@ you can go through every map in the process, find the PFNs, look those up
in kpagecount, and tally up the number of pages that are only referenced
once.
+Exceptions for Shared Memory
+============================
+
+Page table entries for shared pages are cleared when the pages are zapped or
+swapped out. This makes swapped out pages indistinguishable from never-allocated
+ones.
+
+In kernel space, the swap location can still be retrieved from the page cache.
+However, values stored only on the normal PTE get lost irretrievably when the
+page is swapped out (i.e. SOFT_DIRTY).
+
+In user space, whether the page is present, swapped or none can be deduced with
+the help of lseek and/or mincore system calls.
+
+lseek() can differentiate between accessed pages (present or swapped out) and
+holes (none/non-allocated) by specifying the SEEK_DATA flag on the file where
+the pages are backed. For anonymous shared pages, the file can be found in
+``/proc/pid/map_files/``.
+
+mincore() can differentiate between pages in memory (present, including swap
+cache) and out of memory (swapped out or none/non-allocated).
+
Other notes
===========
diff --git a/Documentation/admin-guide/spkguide.txt b/Documentation/admin-guide/spkguide.txt
index 977ab3f5a0a8..1265c1eab31c 100644
--- a/Documentation/admin-guide/spkguide.txt
+++ b/Documentation/admin-guide/spkguide.txt
@@ -543,7 +543,7 @@ As mentioned earlier, Speakup can either be completely compiled into the
kernel, with the exception of the help module, or it can be compiled as
a series of modules. When compiled as modules, Speakup will only be
able to speak some of the bootup messages if your system administrator
-has configured the system to load the modules at boo time. The modules
+has configured the system to load the modules at boot time. The modules
can be loaded after the file systems have been checked and mounted, or
from an initrd. There is a third possibility. Speakup can be compiled
with some components built into the kernel, and others as modules. As