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author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-11-03 08:11:39 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-11-03 08:11:39 +0300 |
commit | 624ad333d49e136c54a342ce0009a05b439616be (patch) | |
tree | 199d58e6fdbc1273f43f6022e62256ccd4601a30 /Documentation/admin-guide | |
parent | 313b6ffc8e90173f1709b2f4bf9d30c4730a1dde (diff) | |
parent | 603bdf5d6c092eb05666decd84288dfda71eee90 (diff) | |
download | linux-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.rst | 22 | ||||
-rw-r--r-- | Documentation/admin-guide/spkguide.txt | 2 |
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 |