wireguard-linux/Documentation/sysctl, branch stable

docs: admin-guide: move sysctl directory to it

2019-07-15T14:03:01Z

The stuff under sysctl describes /sys interface from userspace point of view. So, add it to the admin-guide and remove the :orphan: from its index file. Signed-off-by: Mauro Carvalho Chehab

docs: sysctl: convert to ReST

2019-07-15T12:20:26Z

Rename the /proc/sys/ documentation files to ReST, using the README file as a template for an index.rst, adding the other files there via TOC markup. Despite being written on different times with different styles, try to make them somewhat coherent with a similar look and feel, ensuring that they'll look nice as both raw text file and as via the html output produced by the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab

docs: laptops: convert to ReST

2019-07-15T12:20:25Z

Rename the laptops documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab Acked-by: Andy Shevchenko

Merge tag 'docs-5.3' of git://git.lwn.net/linux

2019-07-09T19:34:26Z

Pull Documentation updates from Jonathan Corbet: "It's been a relatively busy cycle for docs: - A fair pile of RST conversions, many from Mauro. These create more than the usual number of simple but annoying merge conflicts with other trees, unfortunately. He has a lot more of these waiting on the wings that, I think, will go to you directly later on. - A new document on how to use merges and rebases in kernel repos, and one on Spectre vulnerabilities. - Various improvements to the build system, including automatic markup of function() references because some people, for reasons I will never understand, were of the opinion that :c:func:``function()`` is unattractive and not fun to type. - We now recommend using sphinx 1.7, but still support back to 1.4. - Lots of smaller improvements, warning fixes, typo fixes, etc" * tag 'docs-5.3' of git://git.lwn.net/linux: (129 commits) docs: automarkup.py: ignore exceptions when seeking for xrefs docs: Move binderfs to admin-guide Disable Sphinx SmartyPants in HTML output doc: RCU callback locks need only _bh, not necessarily _irq docs: format kernel-parameters -- as code Doc : doc-guide : Fix a typo platform: x86: get rid of a non-existent document Add the RCU docs to the core-api manual Documentation: RCU: Add TOC tree hooks Documentation: RCU: Rename txt files to rst Documentation: RCU: Convert RCU UP systems to reST Documentation: RCU: Convert RCU linked list to reST Documentation: RCU: Convert RCU basic concepts to reST docs: filesystems: Remove uneeded .rst extension on toctables scripts/sphinx-pre-install: fix out-of-tree build docs: zh_CN: submitting-drivers.rst: Remove a duplicated Documentation/ Documentation: PGP: update for newer HW devices Documentation: Add section about CPU vulnerabilities for Spectre Documentation: platform: Delete x86-laptop-drivers.txt docs: Note that :c:func: should no longer be used ...

s390/sclp: remove call home support

2019-06-19T15:54:27Z

This feature has never been used, so remove it. Acked-by: Vasily Gorbik Acked-by: Hendrik Brueckner Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

docs: fix broken documentation links

2019-06-08T19:42:13Z

Mostly due to x86 and acpi conversion, several documentation links are still pointing to the old file. Fix them. Signed-off-by: Mauro Carvalho Chehab Reviewed-by: Wolfram Sang Reviewed-by: Sven Van Asbroeck Reviewed-by: Bhupesh Sharma Acked-by: Mark Brown Signed-off-by: Jonathan Corbet

userfaultfd/sysctl: add vm.unprivileged_userfaultfd

2019-05-14T16:47:45Z

Userfaultfd can be misued to make it easier to exploit existing use-after-free (and similar) bugs that might otherwise only make a short window or race condition available. By using userfaultfd to stall a kernel thread, a malicious program can keep some state that it wrote, stable for an extended period, which it can then access using an existing exploit. While it doesn't cause the exploit itself, and while it's not the only thing that can stall a kernel thread when accessing a memory location, it's one of the few that never needs privilege. We can add a flag, allowing userfaultfd to be restricted, so that in general it won't be useable by arbitrary user programs, but in environments that require userfaultfd it can be turned back on. Add a global sysctl knob "vm.unprivileged_userfaultfd" to control whether userfaultfd is allowed by unprivileged users. When this is set to zero, only privileged users (root user, or users with the CAP_SYS_PTRACE capability) will be able to use the userfaultfd syscalls. Andrea said: : The only difference between the bpf sysctl and the userfaultfd sysctl : this way is that the bpf sysctl adds the CAP_SYS_ADMIN capability : requirement, while userfaultfd adds the CAP_SYS_PTRACE requirement, : because the userfaultfd monitor is more likely to need CAP_SYS_PTRACE : already if it's doing other kind of tracking on processes runtime, in : addition of userfaultfd. In other words both syscalls works only for : root, when the two sysctl are opt-in set to 1. [dgilbert@redhat.com: changelog additions] [akpm@linux-foundation.org: documentation tweak, per Mike] Link: http://lkml.kernel.org/r/20190319030722.12441-2-peterx@redhat.com Signed-off-by: Peter Xu Suggested-by: Andrea Arcangeli Suggested-by: Mike Rapoport Reviewed-by: Mike Rapoport Reviewed-by: Andrea Arcangeli Cc: Paolo Bonzini Cc: Hugh Dickins Cc: Luis Chamberlain Cc: Maxime Coquelin Cc: Maya Gokhale Cc: Jerome Glisse Cc: Pavel Emelyanov Cc: Johannes Weiner Cc: Martin Cracauer Cc: Denis Plotnikov Cc: Marty McFadden Cc: Mike Kravetz Cc: Kees Cook Cc: Mel Gorman Cc: "Kirill A . Shutemov" Cc: "Dr . David Alan Gilbert" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'docs-5.2' of git://git.lwn.net/linux

2019-05-08T19:42:50Z

Pull documentation updates from Jonathan Corbet: "A reasonably busy cycle for docs, including: - Lots of work on the Chinese and Italian translations - Some license-rules clarifications from Christoph - Various build-script fixes - A new document on memory models - RST conversion of the live-patching docs - The usual collection of typo fixes and corrections" * tag 'docs-5.2' of git://git.lwn.net/linux: (140 commits) docs/livepatch: Unify style of livepatch documentation in the ReST format docs: livepatch: convert docs to ReST and rename to *.rst scripts/documentation-file-ref-check: detect broken :doc:`foo` scripts/documentation-file-ref-check: don't parse Next/ dir LICENSES: Rename other to deprecated LICENSES: Clearly mark dual license only licenses docs: Don't reference the ZLib license in license-rules.rst docs/vm: Minor editorial changes in the THP and hugetlbfs docs/vm: add documentation of memory models doc:it_IT: translation alignment doc: fix typo in PGP guide dontdiff: update with Kconfig build artifacts docs/zh_CN: fix typos in 1.Intro.rst file docs/zh_CN: redirect CoC docs to Chinese version doc: mm: migration doesn't use FOLL_SPLIT anymore docs: doc-guide: remove the extension from .rst files doc: kselftest: Fix KBUILD_OUTPUT usage instructions docs: trace: fix some Sphinx warnings docs: speculation.txt: mark example blocks as such docs: ntb.txt: add blank lines to clean up some Sphinx warnings ...

mm: do not boost watermarks to avoid fragmentation for the DISCONTIG memory model

2019-04-26T16:18:05Z

Mikulas Patocka reported that commit 1c30844d2dfe ("mm: reclaim small amounts of memory when an external fragmentation event occurs") "broke" memory management on parisc. The machine is not NUMA but the DISCONTIG model creates three pgdats even though it's a UMA machine for the following ranges 0) Start 0x0000000000000000 End 0x000000003fffffff Size 1024 MB 1) Start 0x0000000100000000 End 0x00000001bfdfffff Size 3070 MB 2) Start 0x0000004040000000 End 0x00000040ffffffff Size 3072 MB Mikulas reported: With the patch 1c30844d2, the kernel will incorrectly reclaim the first zone when it fills up, ignoring the fact that there are two completely free zones. Basiscally, it limits cache size to 1GiB. For example, if I run: # dd if=/dev/sda of=/dev/null bs=1M count=2048 - with the proper kernel, there should be "Buffers - 2GiB" when this command finishes. With the patch 1c30844d2, buffers will consume just 1GiB or slightly more, because the kernel was incorrectly reclaiming them. The page allocator and reclaim makes assumptions that pgdats really represent NUMA nodes and zones represent ranges and makes decisions on that basis. Watermark boosting for small pgdats leads to unexpected results even though this would have behaved reasonably on SPARSEMEM. DISCONTIG is essentially deprecated and even parisc plans to move to SPARSEMEM so there is no need to be fancy, this patch simply disables watermark boosting by default on DISCONTIGMEM. Link: http://lkml.kernel.org/r/20190419094335.GJ18914@techsingularity.net Fixes: 1c30844d2dfe ("mm: reclaim small amounts of memory when an external fragmentation event occurs") Signed-off-by: Mel Gorman Reported-by: Mikulas Patocka Tested-by: Mikulas Patocka Acked-by: Vlastimil Babka Cc: James Bottomley Cc: Matthew Wilcox Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Documentation: fix core_pattern max length

2019-03-25T15:53:56Z

The buffer size for core_pattern is 128, but one character is used for terminating null byte, so the actual limit is 127: # printf '%0999d' > /proc/sys/kernel/core_pattern # tr -d '\n' < /proc/sys/kernel/core_pattern | wc -c 127 Signed-off-by: Jakub Wilk Signed-off-by: Jonathan Corbet