Go to file
Michal Hocko 473738eb78 MIPS: do not use __GFP_REPEAT for order-0 request
Patch series "mm: give __GFP_REPEAT a better semantic".

The main motivation for the change is that the current implementation of
__GFP_REPEAT is not very much useful.

The documentation says:
 * __GFP_REPEAT: Try hard to allocate the memory, but the allocation attempt
 *   _might_ fail.  This depends upon the particular VM implementation.

It just fails to mention that this is true only for large (costly) high
order which has been the case since the flag was introduced.  A similar
semantic would be really helpful for smal orders as well, though,
because we have places where a failure with a specific fallback error
handling is preferred to a potential endless loop inside the page
allocator.

The earlier cleanup dropped __GFP_REPEAT usage for low (!costly) order
users so only those which might use larger orders have stayed.  One new
user added in the meantime is addressed in patch 1.

Let's rename the flag to something more verbose and use it for existing
users.  Semantic for those will not change.  Then implement low
(!costly) orders failure path which is hit after the page allocator is
about to invoke the oom killer.  With that we have a good counterpart
for __GFP_NORETRY and finally can tell try as hard as possible without
the OOM killer.

Xfs code already has an existing annotation for allocations which are
allowed to fail and we can trivially map them to the new gfp flag
because it will provide the semantic KM_MAYFAIL wants.  Christoph didn't
consider the new flag really necessary but didn't respond to the OOM
killer aspect of the change so I have kept the patch.  If this is still
seen as not really needed I can drop the patch.

kvmalloc will allow also !costly high order allocations to retry hard
before falling back to the vmalloc.

drm/i915 asked for the new semantic explicitly.

Memory migration code, especially for the memory hotplug, should back
off rather than invoking the OOM killer as well.

This patch (of 6):

Commit 3377e227af ("MIPS: Add 48-bit VA space (and 4-level page
tables) for 4K pages.") has added a new __GFP_REPEAT user but using this
flag doesn't really make any sense for order-0 request which is the case
here because PUD_ORDER is 0.  __GFP_REPEAT has historically effect only
on allocation requests with order > PAGE_ALLOC_COSTLY_ORDER.

This doesn't introduce any functional change.  This is a preparatory
patch for later work which renames the flag and redefines its semantic.

Link: http://lkml.kernel.org/r/20170623085345.11304-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alex Belits <alex.belits@cavium.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: NeilBrown <neilb@suse.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-12 16:26:03 -07:00
Documentation fault-inject: support systematic fault injection 2017-07-12 16:26:01 -07:00
arch MIPS: do not use __GFP_REPEAT for order-0 request 2017-07-12 16:26:03 -07:00
block Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-07-11 15:36:52 -07:00
certs scripts/spelling.txt: add "intialise(d)" pattern and fix typo instances 2017-05-08 17:15:13 -07:00
crypto dmaengine updates for 4.13-rc1 2017-07-08 12:36:50 -07:00
drivers IB/rxe: do not copy extra stack memory to skb 2017-07-12 16:26:03 -07:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs fault-inject: support systematic fault injection 2017-07-12 16:26:01 -07:00
include random,stackprotect: introduce get_random_canary function 2017-07-12 16:26:03 -07:00
init random: do not ignore early device randomness 2017-07-12 16:26:00 -07:00
ipc ipc/util.h: update documentation for ipc_getref() and ipc_putref() 2017-07-12 16:26:02 -07:00
kernel fork,random: use get_random_canary() to set tsk->stack_canary 2017-07-12 16:26:03 -07:00
lib include/linux/string.h: add the option of fortified string.h functions 2017-07-12 16:26:03 -07:00
mm mm/memory.c: mark create_huge_pmd() inline to prevent build failure 2017-07-12 16:25:59 -07:00
net net/netfilter/x_tables.c: use kvmalloc() in xt_alloc_table_info() 2017-07-12 16:26:02 -07:00
samples kfifo: clean up example to not use page_link 2017-07-12 16:26:01 -07:00
scripts scripts/gdb: lx-dmesg: use explicit encoding=utf8 errors=replace 2017-07-12 16:26:01 -07:00
security include/linux/string.h: add the option of fortified string.h functions 2017-07-12 16:26:03 -07:00
sound main drm pull for v4.13 2017-07-09 18:48:37 -07:00
tools test_sysctl: test against int proc_dointvec() array support 2017-07-12 16:26:00 -07:00
usr ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk. 2017-07-06 16:24:30 -07:00
virt PPC: 2017-07-06 18:38:31 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING [PATCH] update FSF address in COPYING 2005-09-10 10:06:29 -07:00
CREDITS avr32: remove support for AVR32 architecture 2017-05-01 09:27:15 +02:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig kbuild: migrate all arch to the kconfig mainmenu upgrade 2010-09-19 22:54:11 -04:00
MAINTAINERS Merge branch 'i2c/for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2017-07-12 10:04:56 -07:00
Makefile Kbuild thin archives updates for v4.13 2017-07-07 15:11:12 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.