checkpatch: add tests for function pointer style misuses

Kernel style uses function pointers in this form:
"type (*funcptr)(args...)"

Emit warnings when this function pointer form isn't used.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Derek Perrin <d.roc16@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

checkpatch: update the FSF/GPL address check

The FSF address check is a bit too verbose looking for the GPL text.
Quiet it a bit by requiring --strict for the GPL bit.

Also make the address tests match a few uses of abbreviations for street
names and make it case insensitive.

Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

checkpatch: check for if's with unnecessary parentheses

If statements don't need multiple parentheses around tested comparisons
like "if ((foo == bar))".

An == comparison maybe a sign of an intended assignment, so emit a
slightly different message if so.

Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

checkpatch: improve space before tab --fix option

This test should remove all the spaces before a tab not just one space.

Substitute a tab for each 8 space block before a tab and remove less than
8 spaces before a tab.

This SPACE_BEFORE_TAB test is done after CODE_INDENT.

If there are spaces used at the beginning of a line that should be
converted to tabs, please make sure that the CODE_INDENT test and
conversion is done before this SPACE_BEFORE_TAB test and conversion.

Reported-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

checkpatch: add a --fix-inplace option

Add the ability to fix and overwrite existing files/patches instead of
creating a new file "<filename>.EXPERIMENTAL-checkpatch-fixes".

Suggested-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

checkpatch: attempt to find missing switch/case break;

switch case statements missing a break statement are an unfortunately
common error.

e.g.:
  commit 4a2c94c9b6c0 ("HID: kye: Add report fixup for Genius Manticore Keyboard")

case blocks should end in a break/return/goto/continue.

If a fall-through is used, it should have a comment showing that it is
intentional.  Ideally that comment should be something like:
"/* fall-through */"

Add a test to look for missing break statements.

This looks only at the context lines before an inserted case so it's
possible to have false positives when the context contains a close brace
and the break is before the brace and not part of the patch context.

Looking at recent patches, this is a pretty rare occurrence.  The normal
kernel style uses a break as the last line of the previous block.

Signed-off-by: Joe Perches <joe@perche.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

checkpatch: add warning of future __GFP_NOFAIL use

gfp.h and page_alloc.c already specify that __GFP_NOFAIL is deprecated and
no new users should be added.

Add a warning to checkpatch to catch this.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

checkpatch: warn only on "space before semicolon" at end of line

The "space before a non-naked semicolon" test has unwanted output when
used in "for ( ;; )" loops.

Make the test work only on end-of-line statement termination semicolons.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

checkpatch: more comprehensive split strings warning

The current checkpatch test for split strings does not find several
cases that should be found.

For instance:

  /* Else poor success; go back to mode in "active" table */
  } else {
  IWL_DEBUG_RATE(mvm,
-        "LQ: GOING BACK TO THE OLD TABLE suc=%d cur-tpt=%d old-tpt=%d\n",
+        "GOING BACK TO THE OLD TABLE: SR %d "
+        "cur-tpt %d old-tpt %d\n",
         window->success_ratio,
         window->average_tpt,
        lq_sta->last_tpt);

does not currently emit a warning.

Improve the test to find these cases.

Add more exceptions to reduce false positives for assembly and octal/hex
string constants.

Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

firmware/dmi_scan: generalize for use by other archs

This patch makes a couple of changes to the SMBIOS/DMI scanning
code so it can be used on other archs (such as ARM and arm64):
(a) wrap the calls to ioremap()/iounmap(), this allows the use of a
    flavor of ioremap() more suitable for random unaligned access;
(b) allow the non-EFI fallback probe into hardcoded physical address
    0xF0000 to be disabled.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

test: check copy_to/from_user boundary validation

To help avoid an architecture failing to correctly check kernel/user
boundaries when handling copy_to_user, copy_from_user, put_user, or
get_user, perform some simple tests and fail to load if any of them
behave unexpectedly.

Specifically, this is to make sure there is a way to notice if things
like what was fixed in commit 8404663f81d2 ("ARM: 7527/1: uaccess:
explicitly check __user pointer when !CPU_USE_DOMAINS") ever regresses
again, for any architecture.

Additionally, adds new "user" selftest target, which loads this module.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

test: add minimal module for verification testing

This is a pair of test modules I'd like to see in the tree.  Instead of
putting these in lkdtm, where I've been adding various tests that trigger
crashes, these don't make sense there since they need to be either
distinctly separate, or their pass/fail state don't need to crash the
machine.

These live in lib/ for now, along with a few other in-kernel test modules,
and use the slightly more common "test_" naming convention, instead of
"test-".  We should likely standardize on the former:

$ find . -name 'test_*.c' | grep -v /tools/ | wc -l
4
$ find . -name 'test-*.c' | grep -v /tools/ | wc -l
2

The first is entirely a no-op module, designed to allow simple testing of
the module loading and verification interface.  It's useful to have a
module that has no other uses or dependencies so it can be reliably used
for just testing module loading and verification.

The second is a module that exercises the user memory access functions, in
an effort to make sure that we can quickly catch any regressions in
boundary checking (e.g.  like what was recently fixed on ARM).

This patch (of 2):

When doing module loading verification tests (for example, with module
signing, or LSM hooks), it is very handy to have a module that can be
built on all systems under test, isn't auto-loaded at boot, and has no
device or similar dependencies.  This creates the "test_module.ko" module
for that purpose, which only reports its load and unload to printk.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/cmdline.c: declare exported symbols immediately

WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable
+EXPORT_SYMBOL(memparse);

WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable
+EXPORT_SYMBOL(get_option);

WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable
+EXPORT_SYMBOL(get_options);

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Cc: Levente Kurusa <levex@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/cmdline.c: fix style issues

WARNING: space prohibited between function name and open parenthesis '('
+int get_option (char **str, int *pint)

WARNING: space prohibited between function name and open parenthesis '('
+ *pint = simple_strtol (cur, str, 0);

ERROR: trailing whitespace
+ $

WARNING: please, no spaces at the start of a line
+ $

WARNING: space prohibited between function name and open parenthesis '('
+ res = get_option ((char **)&str, ints + i);

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/kstrtox.c: remove redundant cleanup

We can't reach the cleanup code unless the flag KSTRTOX_OVERFLOW is not
set, so there's not no point in clearing a bit that we know is not set.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Acked-by: Levente Kurusa <levex@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

backlight: lp8788: remove unnecessary parentheses

Remove unnecessary parentheses in order to fix the following checkpatch
error.

  ERROR: return is not a function, parentheses are not required

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

backlight: lp855x: remove unnecessary parentheses

Remove unnecessary parentheses in order to fix the following checkpatch
error.

  ERROR: return is not a function, parentheses are not required

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

backlight: kb3886_bl: fix incorrect placement of __initdata marker

The __initdata marker can be virtually anywhere on the line, EXCEPT right
after "struct".  The preferred location is before the "=" sign if there is
one, or before the trailing ";" otherwise.  It also fixes the following
chechpatch warning.

  WARNING: __initdata should be placed after kb3886bl_device_table[]

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

backlight: tosa: use devm_lcd_device_register()

Use devm_lcd_device_register() to make cleanup paths simpler.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

backlight: l4f00242t03: use devm_lcd_device_register()

Use devm_lcd_device_register() to make cleanup paths simpler.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

backlight: jornada720: use devm_lcd_device_register()

Use devm_lcd_device_register() to make cleanup paths simpler,
and remove unnecessary remove().

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

backlight: tosa: use devm_backlight_device_register()

Use devm_backlight_device_register() to make cleanup paths simpler.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

backlight: ot200_bl: use devm_backlight_device_register()

Use devm_backlight_device_register() to make cleanup paths simpler.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

backlight: omap1: use devm_backlight_device_register()

Use devm_backlight_device_register() to make cleanup paths simpler,
and remove unnecessary remove().

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

backlight: hp680_bl: use devm_backlight_device_register()

Use devm_backlight_device_register() to make cleanup paths simpler.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

backlight: jornada720: use devm_backlight_device_register()

Use devm_backlight_device_register() to make cleanup paths simpler,
and remove unnecessary remove().

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MAINTAINERS: remove unnecessary EXYNOS DP DRIVER F: pattern

Remove unnecessary pattern for Exynos DP header from MAINTAINERS file.
After commit f9b1e013f1c6 ("video: exynos_dp: remove non-DT support for
Exynos Display Port"), 'exynos_dp.h' has not been used.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MAINTAINERS: describe differences between F: and N: patterns

There is a difference in how scripts/get_maintainer.pl treats
F: and N: file pattern matches.

Describe those differences in the MAINTAINERS file.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mark Brown <broonie@linaro.org>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MAINTAINERS: add an entry for the Macintosh HFSPlus Filesystem

To make scripts/get_maintainer.pl output something sensible.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

get_maintainer: add commit author information to --rolestats

get_maintainer currently uses "Signed-off-by" style lines to find
interested parties to send patches to when the MAINTAINERS file does not
have a specific section entry with a matching file pattern.

Add statistics for commit authors and lines added and deleted to the
information provided by --rolestats.

These statistics are also emitted whenever --rolestats and --git are
selected even when there is a specified maintainer.

This can have the effect of expanding the number of people that are shown
as possible "maintainers" of a particular file because "authors",
"added_lines", and "removed_lines" are also used as criterion for the
--max-maintainers option separate from the "commit_signers".

The first "--git-max-maintainers" values of each criterion
are emitted.  Any "ties" are not shown.

For example: (forcedeth does not have a named maintainer)

Old output:

$ ./scripts/get_maintainer.pl -f drivers/net/ethernet/nvidia/forcedeth.c
"David S. Miller" <davem@davemloft.net> (commit_signer:8/10=80%)
Jiri Pirko <jiri@resnulli.us> (commit_signer:2/10=20%)
Patrick McHardy <kaber@trash.net> (commit_signer:2/10=20%)
Larry Finger <Larry.Finger@lwfinger.net> (commit_signer:1/10=10%)
Peter Zijlstra <peterz@infradead.org> (commit_signer:1/10=10%)
netdev@vger.kernel.org (open list:NETWORKING DRIVERS)
linux-kernel@vger.kernel.org (open list)

New output:

$ ./scripts/get_maintainer.pl -f drivers/net/ethernet/nvidia/forcedeth.c
"David S. Miller" <davem@davemloft.net> (commit_signer:8/10=80%)
Jiri Pirko <jiri@resnulli.us> (commit_signer:2/10=20%,authored:2/10=20%,removed_lines:3/33=9%)
Patrick McHardy <kaber@trash.net> (commit_signer:2/10=20%,authored:2/10=20%,added_lines:12/95=13%,removed_lines:10/33=30%)
Larry Finger <Larry.Finger@lwfinger.net> (commit_signer:1/10=10%,authored:1/10=10%,added_lines:35/95=37%)
Peter Zijlstra <peterz@infradead.org> (commit_signer:1/10=10%)
"Peter Hüwe" <PeterHuewe@gmx.de> (authored:1/10=10%,removed_lines:15/33=45%)
Joe Perches <joe@perches.com> (authored:1/10=10%)
Neil Horman <nhorman@tuxdriver.com> (added_lines:40/95=42%)
Bill Pemberton <wfp5p@virginia.edu> (removed_lines:3/33=9%)
netdev@vger.kernel.org (open list:NETWORKING DRIVERS)
linux-kernel@vger.kernel.org (open list)

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

printk: flush conflicting continuation line

An earlier newline was missing and current print is from different task.
In this scenario flush the continuation line and store this line
seperatly.

This patch fix the below scenario of timestamp interleaving,
   [   28.154370 ] read_word_reg : reg[0x 3], reg[0x 4]  data [0x 642]
   [   28.155428 ] uart disconnect
   [   31.947341 ] dvfs[cpufreq.c<275>]:plug-in cpu<1> done
   [   28.155445 ] UART detached : send switch state 201
   [   32.014112 ] read_reg : reg[0x 3] data[0x21]

[akpm@linux-foundation.org: simplify and condense the code]
Signed-off-by: Arun KS <getarunks@gmail.com>
Signed-off-by: Arun KS <arun.ks@broadcom.com>
Cc: Joe Perches <joe@perches.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

vsprintf: add %pad extension for dma_addr_t use

dma_addr_t's can be either u32 or u64 depending on a CONFIG option.

There are a few hundred dma_addr_t's printed via either cast to unsigned
long long, unsigned long or no cast at all.

Add %pad to be able to emit them without the cast.

Update Documentation/printk-formats.txt too.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: "Shevchenko, Andriy" <andriy.shevchenko@intel.com>
Cc: Rob Landley <rob@landley.net>
Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

printk/cache: mark printk_once test variable __read_mostly

Add #include <linux/cache.h> to define __read_mostly.

Convert cache.h to use uapi/linux/kernel.h instead
of linux/kernel.h to avoid recursive #includes.

Convert the ALIGN macro to __ALIGN_KERNEL.

printk_once only sets the bool variable tested
once so mark it __read_mostly.

Neaten the alignment so it matches the rest of the
pr_<level>_once #defines too.

Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

dynamic-debug-howto.txt: update since new wildcard support

Add the usage of using new feature wildcard support.

Signed-off-by: Du, Changbin <changbin.du@gmail.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

dynamic_debug: add wildcard support to filter files/functions/modules

Add wildcard '*'(matches zero or more characters) and '?' (matches one
character) support when qurying debug flags.

Now we can open debug messages using keywords. eg:
1. open debug logs in all usb drivers
    echo "file drivers/usb/* +p" > <debugfs>/dynamic_debug/control
2.  open debug logs for usb xhci code
    echo "file *xhci* +p" > <debugfs>/dynamic_debug/control

Signed-off-by: Du, Changbin <changbin.du@gmail.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/parser.c: put EXPORT_SYMBOLs in the conventional place

Cc: Du, Changbin <changbin.du@gmail.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/parser.c: add match_wildcard() function

match_wildcard function is a simple implementation of wildcard
matching algorithm. It only supports two usual wildcardes:
    '*' - matches zero or more characters
    '?' - matches one character
This algorithm is safe since it is non-recursive.

Signed-off-by: Du, Changbin <changbin.du@gmail.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

uapi: convert u64 to __u64 in exported headers

The u64 type is not defined in any exported kernel headers, so trying to
use it will lead to build failures.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/uapi/linux/dn.h: pull in ioctl.h header

This header uses _IOW/_IOR defines but doesn't include ioctl.h for it.
If you try to use this w/out including ioctl.h yourself, it can fail to
build, so add the explicit include.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/uapi/linux/ppp-ioctl.h: pull in ppp_defs.h

This header uses enum NPmode but doesn't include ppp_defs.h.  If you try
to use this header w/out including the defs header first, it leads to a
build failure.  So add the explicit include to fix it.

Don't know of any packages directly impacted, but noticed while building
some ppp code by hand.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

headers_check: special case seqbuf_dump()

"make headers_check" warns about soundcard.h for (at least) five years
now:
    [...]/usr/include/linux/soundcard.h:1054: userspace cannot reference function or variable defined in the kernel

We're apparently stuck with providing OSSlib-3.8 compatibility, so let's
special case this declaration just to silence it.

Notes:

0) Support for OSSlib post 3.8 was already removed in commit 43a990765a
   ("sound: Remove OSSlib stuff from linux/soundcard.h").  Five years have
   passed since that commit: do people still care about OSSlib-3.8?  If
   not, quite a bit of code could be remove from soundcard.h (and probably
   ultrasound.h).

2) By the way, what is actually meant by:
    It is no longer possible to actually link against OSSlib with this
    header, but we still provide these macros for programs using them.

Doesn't that mean compatibility to OSSlib isn't even useful?

3) Anyhow, a previous discussion soundcard.h, which led to that commit,
   starts at https://lkml.org/lkml/2009/1/20/349 .

4) And, yes, I sneaked in a whitespace fix.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Cc: Takashi Iwai <tiwai@suse.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/vlynq/vlynq.c: fix another resource size off by 1 error

We fixed the call to request_mem_region() in commit 3354f73b24c6
("drivers/vlynq/vlynq.c: fix resource size off by 1 error").  But we
need to fix the call the release_mem_region() as well.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/aty/aty128fb.c: fix a warning pertaining to the aty128fb backlight variable

Fix the following warning in the aty128fb driver:

drivers/video/aty/aty128fb.c:363:12: warning: 'backlight' defined but not used [-Wunused-variable]
 static int backlight = 0;
    ^

as the variable's value is only read if CONFIG_FB_ATY128_BACKLIGHT=y.  The
variable is also set if MODULE is unset[*].

[*] I wonder if the conditional wrapper around aty128fb_setup() should be
    using CONFIG_MODULE rather than MODULE.

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/mfd/tps65217.c: fix pointer-integer size mismatch warning in tps65217_probe()

Fix up the following pointer-integer size mismatch warning in
tps65217_probe():

drivers/mfd/tps65217.c: In function 'tps65217_probe':
drivers/mfd/tps65217.c:173:13: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
   chip_id = (unsigned int)match->data;
     ^

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: AnilKumar Ch <anilkumar@ti.com>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/mfd/max8998.c: fix pointer-integer size mismatch warning in max8998_i2c_get_driver_data()

Fix up the following pointer-integer size mismatch warning in
max8998_i2c_get_driver_data():

drivers/mfd/max8998.c: In function 'max8998_i2c_get_driver_data':
drivers/mfd/max8998.c:178:10: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
return (int)match->data;
       ^

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Tomasz Figa <t.figa@samsung.com>
Cc: Mark Brown <broonie@linaro.org>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/gpu/drm/gma500/backlight.c: fix a defined-but-not-used warning for do_gma_backlight_set()

Fix the following warning:

drivers/gpu/drm/gma500/backlight.c:29:13: warning: 'do_gma_backlight_set' defined but not used [-Wunused-function]

by moving the entire function inside the conditional section currently
inside of it.  All the places that call it are so conditionalised.

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/of.h: make for_each_child_of_node() reference its args when CONFIG_OF=n

Make for_each_child_of_node() reference its args when CONFIG_OF=n to
avoid warnings like:

drivers/leds/leds-pwm.c:88:22: warning: unused variable 'node' [-Wunused-variable]
  struct device_node *node = pdev->dev.of_node;
      ^

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

remove extra definitions of U32_MAX

Now that the definition is centralized in <linux/kernel.h>, the
definitions of U32_MAX (and related) elsewhere in the kernel can be
removed.

Signed-off-by: Alex Elder <elder@linaro.org>
Acked-by: Sage Weil <sage@inktank.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel.h: define u8, s8, u32, etc. limits

Create constants that define the maximum and minimum values
representable by the kernel types u8, s8, u16, s16, and so on.

Signed-off-by: Alex Elder <elder@linaro.org>
Cc: Sage Weil <sage@inktank.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

conditionally define U32_MAX

The symbol U32_MAX is defined in several spots.  Change these
definitions to be conditional.  This is in preparation for the next
patch, which centralizes the definition in <linux/kernel.h>.

Signed-off-by: Alex Elder <elder@linaro.org>
Cc: Sage Weil <sage@inktank.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

um: use generic fixmap.h

Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Richard Weinberger <richard@nod.at>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tile: use generic fixmap.h

Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sh: use generic fixmap.h

Signed-off-by: Mark Salter <msalter@redhat.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

powerpc: use generic fixmap.h

Signed-off-by: Mark Salter <msalter@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mips: use generic fixmap.h

Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

microblaze: use generic fixmap.h

Signed-off-by: Mark Salter <msalter@redhat.com>
Tested-by: Michal Simek <monstr@monstr.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

metag: use generic fixmap.h

Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

hexagon: use generic fixmap.h

Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Richard Kuo <rkuo@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

x86: use generic fixmap.h

Signed-off-by: Mark Salter <msalter@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

add generic fixmap.h

Many architectures provide an asm/fixmap.h which defines support for
compile-time 'special' virtual mappings which need to be made before
paging_init() has run.  This support is also used for early ioremap on
x86.  Much of this support is identical across the architectures.  This
patch consolidates all of the common bits into asm-generic/fixmap.h
which is intended to be included from arch/*/include/asm/fixmap.h.

Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jonas Bonn <jonas.bonn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

logfs: check for the return value after calling find_or_create_page()

In get_mapping_page(), after calling find_or_create_page(), the return
value should be checked.

 This patch has been provided:
http://www.spinics.net/lists/linux-fsdevel/msg66948.html but not been
applied now.

Signed-off-by: Younger Liu <liuyiyang@hisense.com>
Cc: Younger Liu <younger.liucn@gmail.com>
Cc: Vyacheslav Dubeyko <slava@dubeyko.com>
Reviewed-by: Prasad Joshi <prasadjoshi.linux@gmail.com>
Cc: Jörn Engel <joern@logfs.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/block/Kconfig: update RAM block device module name

RAM block device support module name changed to brd.ko some years ago
with an "rd" alias to match previous module implementation.  This patch
updates its Kconfig definition.

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/mailbox/omap: make mbox->irq signed for error handling

There is a bug in omap2_mbox_probe() where we try do:

mbox->irq = platform_get_irq(pdev, info->irq_id);
if (mbox->irq < 0) {

The problem is that mbox->irq is unsigned so the error handling doesn't
work.  I've changed it to a signed integer.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Suman Anna <s-anna@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Omar Ramirez Luna <omar.ramirez@copitl.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

asm/types.h: Remove include/asm-generic/int-l64.h

Now all 64-bit architectures have been converted to int-ll64.h, we can
remove int-l64.h in kernelspace.

For backwards compatibility, alpha, ia64, mips64, and powerpc64 still
use int-l64.h in userspace.

This is the (reworked for UAPI) non-documentation part of more than two
year old "asm/types.h: All architectures use int-ll64.h in kernelspace"
(https://lkml.org/lkml/2011/8/13/104)

Since <asm/types.h> (from include/uapi/asm-generic/types.h) is used for
both kernel and user space, include/asm-generic/int-ll64.h cannot just
become include/asm-generic/types.h, as Arnd suggested.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: ignore VM_SOFTDIRTY on VMA merging

The VM_SOFTDIRTY bit affects vma merge routine: if two VMAs has all bits
in vm_flags matched except dirty bit the kernel can't longer merge them
and this forces the kernel to generate new VMAs instead.

It finally may lead to the situation when userspace application reaches
vm.max_map_count limit and get crashed in worse case

 | (gimp:11768): GLib-ERROR **: gmem.c:110: failed to allocate 4096 bytes
 |
 | (file-tiff-load:12038): LibGimpBase-WARNING **: file-tiff-load: gimp_wire_read(): error
 | xinit: connection to X server lost
 |
 | waiting for X server to shut down
 | /usr/lib64/gimp/2.0/plug-ins/file-tiff-load terminated: Hangup
 | /usr/lib64/gimp/2.0/plug-ins/script-fu terminated: Hangup
 | /usr/lib64/gimp/2.0/plug-ins/script-fu terminated: Hangup

  https://bugzilla.kernel.org/show_bug.cgi?id=67651
  https://bugzilla.gnome.org/show_bug.cgi?id=719619#c0

Initial problem came from missed VM_SOFTDIRTY in do_brk() routine but
even if we would set up VM_SOFTDIRTY here, there is still a way to
prevent VMAs from merging: one can call

 | echo 4 > /proc/$PID/clear_refs

and clear all VM_SOFTDIRTY over all VMAs presented in memory map, then
new do_brk() will try to extend old VMA and finds that dirty bit doesn't
match thus new VMA will be generated.

As discussed with Pavel, the right approach should be to ignore
VM_SOFTDIRTY bit when we're trying to merge VMAs and if merge successed
we mark extended VMA with dirty bit where needed.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Reported-by: Bastian Hougaard <gnome@rvzt.net>
Reported-by: Mel Gorman <mgorman@suse.de>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/rmap: fix coccinelle warnings

mm/rmap.c:851:9-10: WARNING: return of 0/1 in function 'invalid_mkclean_vma' with return type bool

 Return statements in functions returning bool should use
 true/false instead of 1/0.

Generated by: coccinelle/misc/boolreturn.cocci

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/swapfile.c: do not skip lowest_bit in scan_swap_map() scan loop

In the second half of scan_swap_map()'s scan loop, offset is set to
si->lowest_bit and then incremented before entering the loop for the
first time, causing si->swap_map[si->lowest_bit] to be skipped.

Signed-off-by: Jamie Liu <jamieliu@google.com>
Cc: Shaohua Li <shli@fusionio.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memcg: remove unused code from kmem_cache_destroy_work_func

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: improve documentation of page_order

Developers occasionally try and optimise PFN scanners by using
page_order but miss that in general it requires zone->lock.  This has
happened twice for compaction.c and rejected both times.  This patch
clarifies the documentation of page_order and adds a note to
compaction.c why page_order is not used.

[akpm@linux-foundation.org: tweaks]
[lauraa@codeaurora.org: Corrected a page_zone(page)->lock reference]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memcg: fix css reference leak and endless loop in mem_cgroup_iter

Commit 19f39402864e ("memcg: simplify mem_cgroup_iter") has reorganized
mem_cgroup_iter code in order to simplify it.  A part of that change was
dropping an optimization which didn't call css_tryget on the root of the
walked tree.  The patch however didn't change the css_put part in
mem_cgroup_iter which excludes root.

This wasn't an issue at the time because __mem_cgroup_iter_next bailed
out for root early without taking a reference as cgroup iterators
(css_next_descendant_pre) didn't visit root themselves.

Nevertheless cgroup iterators have been reworked to visit root by commit
bd8815a6d802 ("cgroup: make css_for_each_descendant() and friends
include the origin css in the iteration") when the root bypass have been
dropped in __mem_cgroup_iter_next.  This means that css_put is not
called for root and so css along with mem_cgroup and other cgroup
internal object tied by css lifetime are never freed.

Fix the issue by reintroducing root check in __mem_cgroup_iter_next and
do not take css reference for it.

This reference counting magic protects us also from another issue, an
endless loop reported by Hugh Dickins when reclaim races with root
removal and css_tryget called by iterator internally would fail.  There
would be no other nodes to visit so __mem_cgroup_iter_next would return
NULL and mem_cgroup_iter would interpret it as "start looping from root
again" and so mem_cgroup_iter would loop forever internally.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reported-by: Hugh Dickins <hughd@google.com>
Tested-by: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Greg Thelen <gthelen@google.com>
Cc: <stable@vger.kernel.org> [3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memcg: fix endless loop caused by mem_cgroup_iter

Hugh has reported an endless loop when the hardlimit reclaim sees the
same group all the time.  This might happen when the reclaim races with
the memcg removal.

shrink_zone
                                                [rmdir root]
  mem_cgroup_iter(root, NULL, reclaim)
    // prev = NULL
    rcu_read_lock()
    mem_cgroup_iter_load
      last_visited = iter->last_visited   // gets root || NULL
      css_tryget(last_visited)            // failed
      last_visited = NULL                 [1]
    memcg = root = __mem_cgroup_iter_next(root, NULL)
    mem_cgroup_iter_update
      iter->last_visited = root;
    reclaim->generation = iter->generation

 mem_cgroup_iter(root, root, reclaim)
   // prev = root
   rcu_read_lock
    mem_cgroup_iter_load
      last_visited = iter->last_visited   // gets root
      css_tryget(last_visited)            // failed
    [1]

The issue seemed to be introduced by commit 5f5781619718 ("memcg: relax
memcg iter caching") which has replaced unconditional css_get/css_put by
css_tryget/css_put for the cached iterator.

This patch fixes the issue by skipping css_tryget on the root of the
tree walk in mem_cgroup_iter_load and symmetrically doesn't release it
in mem_cgroup_iter_update.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reported-by: Hugh Dickins <hughd@google.com>
Tested-by: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Greg Thelen <gthelen@google.com>
Cc: <stable@vger.kernel.org> [3.10+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm, oom: prefer thread group leaders for display purposes

When two threads have the same badness score, it's preferable to kill
the thread group leader so that the actual process name is printed to
the kernel log rather than the thread group name which may be shared
amongst several processes.

This was the behavior when select_bad_process() used to do
for_each_process(), but it now iterates threads instead and leads to
ambiguity.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

doc/kmemcheck: add kmemcheck to kernel-parameters

Add "kmemcheck=xx" to Documentation/kernel-parameters.txt.

Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Cc: Vegard Nossum <vegardno@ifi.uio.no>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Rob Landley <rob@landley.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memcg: iteration skip memcgs not yet fully initialized

It is surprising that the mem_cgroup iterator can return memcgs which
have not yet been fully initialized.  By accident (or trial and error?)
this appears not to present an actual problem; but it may be better to
prevent such surprises, by skipping memcgs not yet online.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org> [3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memcg: fix last_dead_count memory wastage

Shorten mem_cgroup_reclaim_iter.last_dead_count from unsigned long to
int: it's assigned from an int and compared with an int, and adjacent to
an unsigned int: so there's no point to it being unsigned long, which
wasted 104 bytes in every mem_cgroup_per_zone.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: audit/fix non-modular users of module_init in core code

Code that is obj-y (always built-in) or dependent on a bool Kconfig
(built-in or absent) can never be modular.  So using module_init as an
alias for __initcall can be somewhat misleading.

Fix these up now, so that we can relocate module_init from init.h into
module.h in the future.  If we don't do this, we'd have to add module.h
to obviously non-modular code, and that would be a worse thing.

The audit targets the following module_init users for change:
 mm/ksm.c                       bool KSM
 mm/mmap.c                      bool MMU
 mm/huge_memory.c               bool TRANSPARENT_HUGEPAGE
 mm/mmu_notifier.c              bool MMU_NOTIFIER

Note that direct use of __initcall is discouraged, vs.  one of the
priority categorized subgroups.  As __initcall gets mapped onto
device_initcall, our use of subsys_initcall (which makes sense for these
files) will thus change this registration from level 6-device to level
4-subsys (i.e.  slightly earlier).

However no observable impact of that difference has been observed during
testing.

One might think that core_initcall (l2) or postcore_initcall (l3) would
be more appropriate for anything in mm/ but if we look at some actual
init functions themselves, we see things like:

mm/huge_memory.c --> hugepage_init     --> hugepage_init_sysfs
mm/mmap.c        --> init_user_reserve --> sysctl_user_reserve_kbytes
mm/ksm.c         --> ksm_init          --> sysfs_create_group

and hence the choice of subsys_initcall (l4) seems reasonable, and at
the same time minimizes the risk of changing the priority too
drastically all at once.  We can adjust further in the future.

Also, several instances of missing ";" at EOL are fixed.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/mm_init.c: make creation of the mm_kobj happen earlier than device_initcall

The use of __initcall is to be eventually replaced by choosing one from
the prioritized groupings laid out in init.h header:

pure_initcall               0
core_initcall               1
postcore_initcall           2
arch_initcall               3
subsys_initcall             4
fs_initcall                 5
device_initcall             6
late_initcall               7

In the interim, all __initcall are mapped onto device_initcall, which as
can be seen above, comes quite late in the ordering.

Currently the mm_kobj is created with __initcall in mm_sysfs_init().
This means that any other initcalls that want to reference the mm_kobj
have to be device_initcall (or later), otherwise we will for example,
trip the BUG_ON(!kobj) in sysfs's internal_create_group().  This
unfairly restricts those users; for example something that clearly makes
sense to be an arch_initcall will not be able to choose that.

However, upon examination, it is only this way for historical reasons
(i.e.  simply not reprioritized yet).  We see that sysfs is ready quite
earlier in init/main.c via:

 vfs_caches_init
 |_ mnt_init
    |_ sysfs_init

well ahead of the processing of the prioritized calls listed above.

So we can recategorize mm_sysfs_init to be a pure_initcall, which in
turn allows any mm_kobj initcall users a wider range (1 --> 7) of
initcall priorities to choose from.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: show message when updating min_free_kbytes in thp

min_free_kbytes may be raised during THP's initialization.  Sometimes,
this will change the value which was set by the user.  Showing this
message will clarify this confusion.

Only show this message when changing a value which was set by the user
according to Michal Hocko's suggestion.

Show the old value of min_free_kbytes according to Dave Hansen's
suggestion.  This will give user the chance to restore old value of
min_free_kbytes.

Signed-off-by: Han Pingtian <hanpt@linux.vnet.ibm.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory_hotplug.c: move register_memory_resource out of the lock_memory_hotplug

We don't need to do register_memory_resource() under
lock_memory_hotplug() since it has its own lock and doesn't make any
callbacks.

Also register_memory_resource return NULL on failure so we don't have
anything to cleanup at this point.

The reason for this rfc is I was doing some experiments with hotplugging
of memory on some of our larger systems.  While it seems to work, it can
be quite slow.  With some preliminary digging I found that
lock_memory_hotplug is clearly ripe for breakup.

It could be broken up per nid or something but it also covers the
online_page_callback.  The online_page_callback shouldn't be very hard
to break out.

Also there is the issue of various structures(wmarks come to mind) that
are only updated under the lock_memory_hotplug that would need to be
dealt with.

Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Hedi <hedi@sgi.com>
Cc: Mike Travis <travis@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/nobootmem: free_all_bootmem again

get_allocated_memblock_reserved_regions_info() should work if it is
compiled in.  Extended the ifdef around
get_allocated_memblock_memory_regions_info() to include
get_allocated_memblock_reserved_regions_info() as well.  Similar changes
in nobootmem.c/free_low_memory_core_early() where the two functions are
called.

[akpm@linux-foundation.org: cleanup]
Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
Cc: qiuxishi <qiuxishi@huawei.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Daeseok Youn <daeseok.youn@gmail.com>
Cc: Jiang Liu <liuj97@gmail.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: vmscan: call NUMA-unaware shrinkers irrespective of nodemask

If a shrinker is not NUMA-aware, shrink_slab() should call it exactly
once with nid=0, but currently it is not true: if node 0 is not set in
the nodemask or if it is not online, we will not call such shrinkers at
all.  As a result some slabs will be left untouched under some
circumstances.  Let us fix it.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reported-by: Dave Chinner <dchinner@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Glauber Costa <glommer@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: vmscan: shrink all slab objects if tight on memory

When reclaiming kmem, we currently don't scan slabs that have less than
batch_size objects (see shrink_slab_node()):

        while (total_scan >= batch_size) {
                shrinkctl->nr_to_scan = batch_size;
                shrinker->scan_objects(shrinker, shrinkctl);
                total_scan -= batch_size;
        }

If there are only a few shrinkers available, such a behavior won't cause
any problems, because the batch_size is usually small, but if we have a
lot of slab shrinkers, which is perfectly possible since FS shrinkers
are now per-superblock, we can end up with hundreds of megabytes of
practically unreclaimable kmem objects.  For instance, mounting a
thousand of ext2 FS images with a hundred of files in each and iterating
over all the files using du(1) will result in about 200 Mb of FS caches
that cannot be dropped even with the aid of the vm.drop_caches sysctl!

This problem was initially pointed out by Glauber Costa [*].  Glauber
proposed to fix it by making the shrink_slab() always take at least one
pass, to put it simply, turning the scan loop above to a do{}while()
loop.  However, this proposal was rejected, because it could result in
more aggressive and frequent slab shrinking even under low memory
pressure when total_scan is naturally very small.

This patch is a slightly modified version of Glauber's approach.
Similarly to Glauber's patch, it makes shrink_slab() scan less than
batch_size objects, but only if the total number of objects we want to
scan (total_scan) is greater than the total number of objects available
(max_pass).  Since total_scan is biased as half max_pass if the current
delta change is small:

        if (delta < max_pass / 4)
                total_scan = min(total_scan, max_pass / 2);

this is only possible if we are scanning at high prio.  That said, this
patch shouldn't change the vmscan behaviour if the memory pressure is
low, but if we are tight on memory, we will do our best by trying to
reclaim all available objects, which sounds reasonable.

[*] http://www.spinics.net/lists/cgroups/msg06913.html

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Glauber Costa <glommer@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sched/numa: fix setting of cpupid on page migration twice

Commit 7851a45cd3f6 ("mm: numa: Copy cpupid on page migration") copiess
over the cpupid at page migration time.  It is unnecessary to set it
again in migrate_misplaced_transhuge_page().

Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: do_mincore() cleanup

Two cleanups:
1. remove redundant codes for hugetlb pages.
2. end = pmd_addr_end(addr, end) restricts [addr, end) within PMD_SIZE,
   this may increase do_mincore() calls, remove it.

Signed-off-by: Jianguo Wu <wujianguo@huawei.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: qiuxishi <qiuxishi@huawei.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/genalloc.h: spinlock_t needs spinlock_types.h

Compiling a C file which includes genalloc.h but without
spinlock_types.h being included before, we will see the compile error
below.

 include/linux/genalloc.h:54:2: error: unknown type name `spinlock_t'

Include spinlock_types.h from genalloc.h to fix the problem.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/trace/postprocess/trace-vmscan-postprocess.pl: fix the traceevent regex

When irq, preempt and lockdep fields are printed (field 3 in the example
below) in the trace output, the script fails.

An example entry:
  kswapd0-610   [000] ...1   158.112152: mm_vmscan_kswapd_wake: nid=0 order=0

Signed-off-by: Vinayak Menon <vinayakm.list@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: prevent setting of a value less than 0 to min_free_kbytes

If echo -1 > /proc/vm/sys/min_free_kbytes, the system will hang.  Changing
proc_dointvec() to proc_dointvec_minmax() in the
min_free_kbytes_sysctl_handler() can prevent this to happen.

mhocko said:

: You can still do echo $BIG_VALUE > /proc/vm/sys/min_free_kbytes and make
: your machine unusable but I agree that proc_dointvec_minmax is more
: suitable here as we already have:
:
:  .proc_handler   = min_free_kbytes_sysctl_handler,
:  .extra1         = &zero,
:
: It used to work properly but then 6fce56ec91b5 ("sysctl: Remove references
: to ctl_name and strategy from the generic sysctl table") has removed
: sysctl_intvec strategy and so extra1 is ignored.

Signed-off-by: Han Pingtian <hanpt@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: new_vma_page() cannot see NULL vma for hugetlb pages

Commit 11c731e81bb0 ("mm/mempolicy: fix !vma in new_vma_page()") has
removed BUG_ON(!vma) from new_vma_page which is partially correct
because page_address_in_vma will return EFAULT for non-linear mappings
and at least shared shmem might be mapped this way.

The patch also tried to prevent NULL ptr for hugetlb pages which is not
correct AFAICS because hugetlb pages cannot be mapped as VM_NONLINEAR
and other conditions in page_address_in_vma seem to be legit and catch
real bugs.

This patch restores BUG_ON for PageHuge to catch potential issues when
the to-be-migrated page is not setup properly.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory-failure.c: shift page lock from head page to tail page after thp split

After thp split in hwpoison_user_mappings(), we hold page lock on the
raw error page only between try_to_unmap, hence we are in danger of race
condition.

I found in the RHEL7 MCE-relay testing that we have "bad page" error
when a memory error happens on a thp tail page used by qemu-kvm:

  Triggering MCE exception on CPU 10
  mce: [Hardware Error]: Machine check events logged
  MCE exception done on CPU 10
  MCE 0x38c535: Killing qemu-kvm:8418 due to hardware memory corruption
  MCE 0x38c535: dirty LRU page recovery: Recovered
  qemu-kvm[8418]: segfault at 20 ip 00007ffb0f0f229a sp 00007fffd6bc5240 error 4 in qemu-kvm[7ffb0ef14000+420000]
  BUG: Bad page state in process qemu-kvm  pfn:38c400
  page:ffffea000e310000 count:0 mapcount:0 mapping:          (null) index:0x7ffae3c00
  page flags: 0x2fffff0008001d(locked|referenced|uptodate|dirty|swapbacked)
  Modules linked in: hwpoison_inject mce_inject vhost_net macvtap macvlan ...
  CPU: 0 PID: 8418 Comm: qemu-kvm Tainted: G   M        --------------   3.10.0-54.0.1.el7.mce_test_fixed.x86_64 #1
  Hardware name: NEC NEC Express5800/R120b-1 [N8100-1719F]/MS-91E7-001, BIOS 4.6.3C19 02/10/2011
  Call Trace:
    dump_stack+0x19/0x1b
    bad_page.part.59+0xcf/0xe8
    free_pages_prepare+0x148/0x160
    free_hot_cold_page+0x31/0x140
    free_hot_cold_page_list+0x46/0xa0
    release_pages+0x1c1/0x200
    free_pages_and_swap_cache+0xad/0xd0
    tlb_flush_mmu.part.46+0x4c/0x90
    tlb_finish_mmu+0x55/0x60
    exit_mmap+0xcb/0x170
    mmput+0x67/0xf0
    vhost_dev_cleanup+0x231/0x260 [vhost_net]
    vhost_net_release+0x3f/0x90 [vhost_net]
    __fput+0xe9/0x270
    ____fput+0xe/0x10
    task_work_run+0xc4/0xe0
    do_exit+0x2bb/0xa40
    do_group_exit+0x3f/0xa0
    get_signal_to_deliver+0x1d0/0x6e0
    do_signal+0x48/0x5e0
    do_notify_resume+0x71/0xc0
    retint_signal+0x48/0x8c

The reason of this bug is that a page fault happens before unlocking the
head page at the end of memory_failure().  This strange page fault is
trying to access to address 0x20 and I'm not sure why qemu-kvm does
this, but anyway as a result the SIGSEGV makes qemu-kvm exit and on the
way we catch the bad page bug/warning because we try to free a locked
page (which was the former head page.)

To fix this, this patch suggests to shift page lock from head page to
tail page just after thp split.  SIGSEGV still happens, but it affects
only error affected VMs, not a whole system.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> [3.9+] # a3e0f9e47d5ef "mm/memory-failure.c: transfer page count from head page to tail page after split thp"
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

numa: add a sysctl for numa_balancing

Add a working sysctl to enable/disable automatic numa memory balancing
at runtime.

This allows us to track down performance problems with this feature and
is generally a good idea.

This was possible earlier through debugfs, but only with special
debugging options set.  Also fix the boot message.

[akpm@linux-foundation.org: s/sched_numa_balancing/sysctl_numa_balancing/]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: free memblock.memory in free_all_bootmem

When calling free_all_bootmem() the free areas under memblock's control
are released to the buddy allocator.  Additionally the reserved list is
freed if it was reallocated by memblock.  The same should apply for the
memory list.

Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/nobootmem.c: add return value check in __alloc_memory_core_early()

When memblock_reserve() fails because memblock.reserved.regions cannot
be resized, the caller (e.g.  alloc_bootmem()) is not informed of the
failed allocation.  Therefore alloc_bootmem() silently returns the same
pointer again and again.

This patch adds a check for the return value of memblock_reserve() in
__alloc_memory_core().

Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memcg: rework memcg_update_kmem_limit synchronization

Currently we take both the memcg_create_mutex and the set_limit_mutex
when we enable kmem accounting for a memory cgroup, which makes kmem
activation events serialize with both memcg creations and other memcg
limit updates (memory.limit, memory.memsw.limit).  However, there is no
point in such strict synchronization rules there.

First, the set_limit_mutex was introduced to keep the memory.limit and
memory.memsw.limit values in sync.  Since memory.kmem.limit can be set
independently of them, it is better to introduce a separate mutex to
synchronize against concurrent kmem limit updates.

Second, we take the memcg_create_mutex in order to make sure all
children of this memcg will be kmem-active as well.  For achieving that,
it is enough to hold this mutex only while checking if
memcg_has_children() though.  This guarantees that if a child is added
after we checked that the memcg has no children, the newly added cgroup
will see its parent kmem-active (of course if the latter succeeded), and
call kmem activation for itself.

This patch simplifies the locking rules of memcg_update_kmem_limit()
according to these considerations.

[vdavydov@parallels.com: fix unintialized var warning]
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memcg: remove KMEM_ACCOUNTED_ACTIVATED flag

Currently we have two state bits in mem_cgroup::kmem_account_flags
regarding kmem accounting activation, ACTIVATED and ACTIVE.  We start
kmem accounting only if both flags are set (memcg_can_account_kmem()),
plus throughout the code there are several places where we check only
the ACTIVE flag, but we never check the ACTIVATED flag alone.  These
flags are both set from memcg_update_kmem_limit() under the
set_limit_mutex, the ACTIVE flag always being set after ACTIVATED, and
they never get cleared.  That said checking if both flags are set is
equivalent to checking only for the ACTIVE flag, and since there is no
ACTIVATED flag checks, we can safely remove the ACTIVATED flag, and
nothing will change.

Let's try to understand what was the reason for introducing these flags.
The purpose of the ACTIVE flag is clear - it states that kmem should be
accounting to the cgroup.  The only requirement for it is that it should
be set after we have fully initialized kmem accounting bits for the
cgroup and patched all static branches relating to kmem accounting.
Since we always check if static branch is enabled before actually
considering if we should account (otherwise we wouldn't benefit from
static branching), this guarantees us that we won't skip a commit or
uncharge after a charge due to an unpatched static branch.

Now let's move on to the ACTIVATED bit.  As I proved in the beginning of
this message, it is absolutely useless, and removing it will change
nothing.  So what was the reason introducing it?

The ACTIVATED flag was introduced by commit a8964b9b84f9 ("memcg: use
static branches when code not in use") in order to guarantee that
static_key_slow_inc(&memcg_kmem_enabled_key) would be called only once
for each memory cgroup when its kmem accounting was activated.  The
point was that at that time the memcg_update_kmem_limit() function's
work-flow looked like this:

        bool must_inc_static_branch = false;

        cgroup_lock();
        mutex_lock(&set_limit_mutex);
        if (!memcg->kmem_account_flags && val != RESOURCE_MAX) {
                /* The kmem limit is set for the first time */
                ret = res_counter_set_limit(&memcg->kmem, val);

                memcg_kmem_set_activated(memcg);
                must_inc_static_branch = true;
        } else
                ret = res_counter_set_limit(&memcg->kmem, val);
        mutex_unlock(&set_limit_mutex);
        cgroup_unlock();

        if (must_inc_static_branch) {
                /* We can't do this under cgroup_lock */
                static_key_slow_inc(&memcg_kmem_enabled_key);
                memcg_kmem_set_active(memcg);
        }

So that without the ACTIVATED flag we could race with other threads
trying to set the limit and increment the static branching ref-counter
more than once.  Today we call the whole memcg_update_kmem_limit()
function under the set_limit_mutex and this race is impossible.

As now we understand why the ACTIVATED bit was introduced and why we
don't need it now, and know that removing it will change nothing anyway,
let's get rid of it.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memcg, slab: RCU protect memcg_params for root caches

We relocate root cache's memcg_params whenever we need to grow the
memcg_caches array to accommodate all kmem-active memory cgroups.
Currently on relocation we free the old version immediately, which can
lead to use-after-free, because the memcg_caches array is accessed
lock-free (see cache_from_memcg_idx()).  This patch fixes this by making
memcg_params RCU-protected for root caches.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

slab: do not panic if we fail to create memcg cache

There is no point in flooding logs with warnings or especially crashing
the system if we fail to create a cache for a memcg.  In this case we
will be accounting the memcg allocation to the root cgroup until we
succeed to create its own cache, but it isn't that critical.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memcg: get rid of kmem_cache_dup()

kmem_cache_dup() is only called from memcg_create_kmem_cache().  The
latter, in fact, does nothing besides this, so let's fold
kmem_cache_dup() into memcg_create_kmem_cache().

This patch also makes the memcg_cache_mutex private to
memcg_create_kmem_cache(), because it is not used anywhere else.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memcg, slab: fix races in per-memcg cache creation/destruction

We obtain a per-memcg cache from a root kmem_cache by dereferencing an
entry of the root cache's memcg_params::memcg_caches array.  If we find
no cache for a memcg there on allocation, we initiate the memcg cache
creation (see memcg_kmem_get_cache()).  The cache creation proceeds
asynchronously in memcg_create_kmem_cache() in order to avoid lock
clashes, so there can be several threads trying to create the same
kmem_cache concurrently, but only one of them may succeed.  However, due
to a race in the code, it is not always true.  The point is that the
memcg_caches array can be relocated when we activate kmem accounting for
a memcg (see memcg_update_all_caches(), memcg_update_cache_size()).  If
memcg_update_cache_size() and memcg_create_kmem_cache() proceed
concurrently as described below, we can leak a kmem_cache.

Asume two threads schedule creation of the same kmem_cache.  One of them
successfully creates it.  Another one should fail then, but if
memcg_create_kmem_cache() interleaves with memcg_update_cache_size() as
follows, it won't:

  memcg_create_kmem_cache()             memcg_update_cache_size()
  (called w/o mutexes held)             (called with slab_mutex,
                                         set_limit_mutex held)
  -------------------------             -------------------------

  mutex_lock(&memcg_cache_mutex)

                                        s->memcg_params=kzalloc(...)

  new_cachep=cache_from_memcg_idx(cachep,idx)
  // new_cachep==NULL => proceed to creation

                                        s->memcg_params->memcg_caches[i]
                                            =cur_params->memcg_caches[i]

  // kmem_cache_create_memcg takes slab_mutex
  // so we will hang around until
  // memcg_update_cache_size finishes, but
  // nothing will prevent it from succeeding so
  // memcg_caches[idx] will be overwritten in
  // memcg_register_cache!

  new_cachep = kmem_cache_create_memcg(...)
  mutex_unlock(&memcg_cache_mutex)

Let's fix this by moving the check for existence of the memcg cache to
kmem_cache_create_memcg() to be called under the slab_mutex and make it
return NULL if so.

A similar race is possible when destroying a memcg cache (see
kmem_cache_destroy()).  Since memcg_unregister_cache(), which clears the
pointer in the memcg_caches array, is called w/o protection, we can race
with memcg_update_cache_size() and omit clearing the pointer.  Therefore
memcg_unregister_cache() should be moved before we release the
slab_mutex.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memcg: fix possible NULL deref while traversing memcg_slab_caches list

All caches of the same memory cgroup are linked in the memcg_slab_caches
list via kmem_cache::memcg_params::list.  This list is traversed, for
example, when we read memory.kmem.slabinfo.

Since the list actually consists of memcg_cache_params objects, we have
to convert an element of the list to a kmem_cache object using
memcg_params_to_cache(), which obtains the pointer to the cache from the
memcg_params::memcg_caches array of the corresponding root cache.  That
said the pointer to a kmem_cache in its parent's memcg_params must be
initialized before adding the cache to the list, and cleared only after
it has been unlinked.  Currently it is vice-versa, which can result in a
NULL ptr dereference while traversing the memcg_slab_caches list.  This
patch restores the correct order.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memcg, slab: fix barrier usage when accessing memcg_caches

Each root kmem_cache has pointers to per-memcg caches stored in its
memcg_params::memcg_caches array.  Whenever we want to allocate a slab
for a memcg, we access this array to get per-memcg cache to allocate
from (see memcg_kmem_get_cache()).  The access must be lock-free for
performance reasons, so we should use barriers to assert the kmem_cache
is up-to-date.

First, we should place a write barrier immediately before setting the
pointer to it in the memcg_caches array in order to make sure nobody
will see a partially initialized object.  Second, we should issue a read
barrier before dereferencing the pointer to conform to the write
barrier.

However, currently the barrier usage looks rather strange.  We have a
write barrier *after* setting the pointer and a read barrier *before*
reading the pointer, which is incorrect.  This patch fixes this.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>