Merge tag 'docs-6.1' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "There's not a huge amount of activity in the docs tree this time
  around, but a few significant changes even so:

   - A complete rewriting of the top-level index.rst file, which mostly
     reflects itself in a redone top page in the HTML-rendered docs. The
     hope is that the new organization will be a friendlier starting
     point for both users and developers.

   - Some math-rendering improvements.

   - A coding-style.rst update on the use of BUG() and WARN()

   - A big maintainer-PHP guide update.

   - Some code-of-conduct updates

   - More Chinese translation work

  Plus the usual pile of typo fixes, corrections, and updates"

* tag 'docs-6.1' of git://git.lwn.net/linux: (66 commits)
  checkpatch: warn on usage of VM_BUG_ON() and other BUG variants
  coding-style.rst: document BUG() and WARN() rules ("do not crash the kernel")
  Documentation: devres: add missing IO helper
  Documentation: devres: update IRQ helper
  Documentation/mm: modify page_referenced to folio_referenced
  Documentation/CoC: Reflect current CoC interpretation and practices
  docs/doc-guide: Add documentation on SPHINX_IMGMATH
  docs: process/5.Posting.rst: clarify use of Reported-by: tag
  docs, kprobes: Fix the wrong location of Kprobes
  docs: add a man-pages link to the front page
  docs: put atomic*.txt and memory-barriers.txt into the core-api book
  docs: move asm-annotations.rst into core-api
  docs: remove some index.rst cruft
  docs: reconfigure the HTML left column
  docs: Rewrite the front page
  docs: promote the title of process/index.rst
  Documentation: devres: add missing SPI helper
  Documentation: devres: add missing PINCTRL helpers
  docs: hugetlbpage.rst: fix a typo of hugepage size
  docs/zh_CN: Add new translation of admin-guide/bootconfig.rst
  ...

84 files changed, 2957 insertions, 1731 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-bcma b/Documentation/ABI/testing/sysfs-bus-bcma
index 721b4aea3020..e93d3ddca844 100644
--- a/Documentation/ABI/testing/sysfs-bus-bcma
+++ b/Documentation/ABI/testing/sysfs-bus-bcma
@@ -3,7 +3,7 @@ Date:		May 2011
 KernelVersion:	3.0
 Contact:	Rafał Miłecki <zajec5@gmail.com>
 Description:
-		Each BCMA core has it's manufacturer id. See
+		Each BCMA core has its manufacturer id. See
 		include/linux/bcma/bcma.h for possible values.
 
 What:		/sys/bus/bcma/devices/.../id
diff --git a/Documentation/ABI/testing/sysfs-bus-fcoe b/Documentation/ABI/testing/sysfs-bus-fcoe
index 8fe787cc4ab7..5a4f2091ac37 100644
--- a/Documentation/ABI/testing/sysfs-bus-fcoe
+++ b/Documentation/ABI/testing/sysfs-bus-fcoe
@@ -31,7 +31,7 @@ Description:	'FCoE Controller' instances on the fcoe bus.
 		1) Write interface name to ctlr_create 2) Configure the FCoE
 		Controller (ctlr_X) 3) Enable the FCoE Controller to begin
 		discovery and login. The FCoE Controller is destroyed by
-		writing it's name, i.e. ctlr_X to the ctlr_delete file.
+		writing its name, i.e. ctlr_X to the ctlr_delete file.
 
 Attributes:
 
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-proximity b/Documentation/ABI/testing/sysfs-bus-iio-proximity
index 3aac6dab8775..9b9d1cc9b703 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio-proximity
+++ b/Documentation/ABI/testing/sysfs-bus-iio-proximity
@@ -18,7 +18,7 @@ Description:
 		on the signal from which time of flight measurements are
 		taken.
 		The appropriate values to take is dependent on both the
-		sensor and it's operating environment:
+		sensor and its operating environment:
 		* as3935 (0-31 range)
 		18 = indoors (default)
 		14 = outdoors
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 760c889b6cd1..f54867cadb0f 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -296,7 +296,7 @@ Description:	Processor frequency boosting control
 
 		This switch controls the boost setting for the whole system.
 		Boosting allows the CPU and the firmware to run at a frequency
-		beyond it's nominal limit.
+		beyond its nominal limit.
 
 		More details can be found in
 		Documentation/admin-guide/pm/cpufreq.rst
diff --git a/Documentation/ABI/testing/sysfs-platform-chipidea-usb2 b/Documentation/ABI/testing/sysfs-platform-chipidea-usb2
index b0f4684a83fe..b9f7d924f28a 100644
--- a/Documentation/ABI/testing/sysfs-platform-chipidea-usb2
+++ b/Documentation/ABI/testing/sysfs-platform-chipidea-usb2
@@ -2,8 +2,8 @@ What:		/sys/bus/platform/devices/ci_hdrc.0/role
 Date:		Mar 2017
 Contact:	Peter Chen <peter.chen@nxp.com>
 Description:
-		It returns string "gadget" or "host" when read it, it indicates
-		current controller role.
+		When read, it returns string "gadget" or "host", indicating
+		the current controller role.
 
-		It will do role switch when write "gadget" or "host" to it.
+		It will do role switch when "gadget" or "host" is written to it.
 		Only controller at dual-role configuration supports writing.
diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power
index 90ec4987074b..f99d433ff311 100644
--- a/Documentation/ABI/testing/sysfs-power
+++ b/Documentation/ABI/testing/sysfs-power
@@ -152,7 +152,7 @@ Description:
 		case further investigation is required to determine which
 		device is causing the problem.  Note that genuine RTC clock
 		values (such as when pm_trace has not been used), can still
-		match a device and output it's name here.
+		match a device and output its name here.
 
 What:		/sys/power/pm_async
 Date:		January 2009
diff --git a/Documentation/RCU/checklist.rst b/Documentation/RCU/checklist.rst
index 178ca7547b98..048c5bc1f813 100644
--- a/Documentation/RCU/checklist.rst
+++ b/Documentation/RCU/checklist.rst
@@ -486,6 +486,6 @@ over a rather long period of time, but improvements are always welcome!
 	So if you need to wait for both an RCU grace period and for
 	all pre-existing call_rcu() callbacks, you will need to execute
 	both rcu_barrier() and synchronize_rcu(), if necessary, using
-	something like workqueues to to execute them concurrently.
+	something like workqueues to execute them concurrently.
 
 	See rcubarrier.rst for more information.
diff --git a/Documentation/RCU/lockdep.rst b/Documentation/RCU/lockdep.rst
index cc860a0c296b..a94f55991a71 100644
--- a/Documentation/RCU/lockdep.rst
+++ b/Documentation/RCU/lockdep.rst
@@ -61,7 +61,7 @@ checking of rcu_dereference() primitives:
 	rcu_access_pointer(p):
 		Return the value of the pointer and omit all barriers,
 		but retain the compiler constraints that prevent duplicating
-		or coalescsing.  This is useful when when testing the
+		or coalescsing.  This is useful when testing the
 		value of the pointer itself, for example, against NULL.
 
 The rcu_dereference_check() check expression can be any boolean
diff --git a/Documentation/admin-guide/README.rst b/Documentation/admin-guide/README.rst
index 9eb6b9042f75..9a969c0157f1 100644
--- a/Documentation/admin-guide/README.rst
+++ b/Documentation/admin-guide/README.rst
@@ -262,8 +262,6 @@ Compiling the kernel
  - Make sure you have at least gcc 5.1 available.
    For more information, refer to :ref:`Documentation/process/changes.rst <changes>`.
 
-   Please note that you can still run a.out user programs with this kernel.
-
  - Do a ``make`` to create a compressed kernel image. It is also
    possible to do ``make install`` if you have lilo installed to suit the
    kernel makefiles, but you may want to check your particular lilo setup first.
@@ -332,85 +330,10 @@ Compiling the kernel
 If something goes wrong
 -----------------------
 
- - If you have problems that seem to be due to kernel bugs, please check
-   the file MAINTAINERS to see if there is a particular person associated
-   with the part of the kernel that you are having trouble with. If there
-   isn't anyone listed there, then the second best thing is to mail
-   them to me (torvalds@linux-foundation.org), and possibly to any other
-   relevant mailing-list or to the newsgroup.
-
- - In all bug-reports, *please* tell what kernel you are talking about,
-   how to duplicate the problem, and what your setup is (use your common
-   sense).  If the problem is new, tell me so, and if the problem is
-   old, please try to tell me when you first noticed it.
-
- - If the bug results in a message like::
-
-     unable to handle kernel paging request at address C0000010
-     Oops: 0002
-     EIP:   0010:XXXXXXXX
-     eax: xxxxxxxx   ebx: xxxxxxxx   ecx: xxxxxxxx   edx: xxxxxxxx
-     esi: xxxxxxxx   edi: xxxxxxxx   ebp: xxxxxxxx
-     ds: xxxx  es: xxxx  fs: xxxx  gs: xxxx
-     Pid: xx, process nr: xx
-     xx xx xx xx xx xx xx xx xx xx
-
-   or similar kernel debugging information on your screen or in your
-   system log, please duplicate it *exactly*.  The dump may look
-   incomprehensible to you, but it does contain information that may
-   help debugging the problem.  The text above the dump is also
-   important: it tells something about why the kernel dumped code (in
-   the above example, it's due to a bad kernel pointer). More information
-   on making sense of the dump is in Documentation/admin-guide/bug-hunting.rst
-
- - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump
-   as is, otherwise you will have to use the ``ksymoops`` program to make
-   sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred).
-   This utility can be downloaded from
-   https://www.kernel.org/pub/linux/utils/kernel/ksymoops/ .
-   Alternatively, you can do the dump lookup by hand:
-
- - In debugging dumps like the above, it helps enormously if you can
-   look up what the EIP value means.  The hex value as such doesn't help
-   me or anybody else very much: it will depend on your particular
-   kernel setup.  What you should do is take the hex value from the EIP
-   line (ignore the ``0010:``), and look it up in the kernel namelist to
-   see which kernel function contains the offending address.
-
-   To find out the kernel function name, you'll need to find the system
-   binary associated with the kernel that exhibited the symptom.  This is
-   the file 'linux/vmlinux'.  To extract the namelist and match it against
-   the EIP from the kernel crash, do::
-
-     nm vmlinux | sort | less
-
-   This will give you a list of kernel addresses sorted in ascending
-   order, from which it is simple to find the function that contains the
-   offending address.  Note that the address given by the kernel
-   debugging messages will not necessarily match exactly with the
-   function addresses (in fact, that is very unlikely), so you can't
-   just 'grep' the list: the list will, however, give you the starting
-   point of each kernel function, so by looking for the function that
-   has a starting address lower than the one you are searching for but
-   is followed by a function with a higher address you will find the one
-   you want.  In fact, it may be a good idea to include a bit of
-   "context" in your problem report, giving a few lines around the
-   interesting one.
-
-   If you for some reason cannot do the above (you have a pre-compiled
-   kernel image or similar), telling me as much about your setup as
-   possible will help.  Please read
-   'Documentation/admin-guide/reporting-issues.rst' for details.
-
- - Alternatively, you can use gdb on a running kernel. (read-only; i.e. you
-   cannot change values or set break points.) To do this, first compile the
-   kernel with -g; edit arch/x86/Makefile appropriately, then do a ``make
-   clean``. You'll also need to enable CONFIG_PROC_FS (via ``make config``).
-
-   After you've rebooted with the new kernel, do ``gdb vmlinux /proc/kcore``.
-   You can now use all the usual gdb commands. The command to look up the
-   point where your system crashed is ``l *0xXXXXXXXX``. (Replace the XXXes
-   with the EIP value.)
-
-   gdb'ing a non-running kernel currently fails because ``gdb`` (wrongly)
-   disregards the starting offset for which the kernel is compiled.
+If you have problems that seem to be due to kernel bugs, please follow the
+instructions at 'Documentation/admin-guide/reporting-issues.rst'.
+
+Hints on understanding kernel bug reports are in
+'Documentation/admin-guide/bug-hunting.rst'. More on debugging the kernel
+with gdb is in 'Documentation/dev-tools/gdb-kernel-debugging.rst' and
+'Documentation/dev-tools/kgdb.rst'.
diff --git a/Documentation/admin-guide/hw-vuln/spectre.rst b/Documentation/admin-guide/hw-vuln/spectre.rst
index 2ce2a38cdd55..c4dcdb3d0d45 100644
--- a/Documentation/admin-guide/hw-vuln/spectre.rst
+++ b/Documentation/admin-guide/hw-vuln/spectre.rst
@@ -613,6 +613,7 @@ kernel command line.
                 eibrs                   enhanced IBRS
                 eibrs,retpoline         enhanced IBRS + Retpolines
                 eibrs,lfence            enhanced IBRS + LFENCE
+                ibrs                    use IBRS to protect kernel
 
 		Not specifying this option is equivalent to
 		spectre_v2=auto.
diff --git a/Documentation/admin-guide/kdump/vmcoreinfo.rst b/Documentation/admin-guide/kdump/vmcoreinfo.rst
index 8419019b6a88..6726f439958c 100644
--- a/Documentati