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Michal Hocko 9980d744a0 mm, hugetlb: get rid of surplus page accounting tricks
alloc_surplus_huge_page increases the pool size and the number of
surplus pages opportunistically to prevent from races with the pool size
change.  See commit d1c3fb1f8f ("hugetlb: introduce
nr_overcommit_hugepages sysctl") for more details.

The resulting code is unnecessarily hairy, cause code duplication and
doesn't allow to share the allocation paths.  Moreover pool size changes
tend to be very seldom so optimizing for them is not really reasonable.
Simplify the code and allow to allocate a fresh surplus page as long as
we are under the overcommit limit and then recheck the condition after
the allocation and drop the new page if the situation has changed.  This
should provide a reasonable guarantee that an abrupt allocation requests
will not go way off the limit.

If we consider races with the pool shrinking and enlarging then we
should be reasonably safe as well.  In the first case we are off by one
in the worst case and the second case should work OK because the page is
not yet visible.  We can waste CPU cycles for the allocation but that
should be acceptable for a relatively rare condition.

Link: http://lkml.kernel.org/r/20180103093213.26329-5-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Reale <ar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-01-31 17:18:40 -08:00
arch mm/thp: remove pmd_huge_split_prepare() 2018-01-31 17:18:38 -08:00
block Merge branch 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 17:58:07 -08:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto Merge branch 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 17:58:07 -08:00
Documentation mm, hugetlb: remove hugepages_treat_as_movable sysctl 2018-01-31 17:18:37 -08:00
drivers mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks 2018-01-31 17:18:38 -08:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs userfaultfd: convert to use anon_inode_getfd() 2018-01-31 17:18:39 -08:00
include mm, hugetlb: do not rely on overcommit limit during migration 2018-01-31 17:18:40 -08:00
init init_task out-of-lining 2018-01-29 09:08:34 -08:00
ipc Merge branch 'work.mqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 18:32:21 -08:00
kernel mm, hugetlb: remove hugepages_treat_as_movable sysctl 2018-01-31 17:18:37 -08:00
lib First merge window pull request for 4.16 2018-01-31 12:05:10 -08:00
mm mm, hugetlb: get rid of surplus page accounting tricks 2018-01-31 17:18:40 -08:00
net First merge window pull request for 4.16 2018-01-31 12:05:10 -08:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2017-12-03 13:08:30 -05:00
scripts scripts/tags.sh: change find_other_sources() for include directories 2018-01-31 17:18:34 -08:00
security Merge branch 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 17:58:07 -08:00
sound Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-31 09:25:20 -08:00
tools memfd-test: run fuse test on hugetlb backend memory 2018-01-31 17:18:39 -08:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks 2018-01-31 17:18:38 -08:00
.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 misc updates for v4.15 2017-11-17 17:51:33 -08:00
.mailmap mailmap: update Mark Yao's email address 2018-01-04 16:45:09 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS First merge window pull request for 4.16 2018-01-31 12:05:10 -08:00
Makefile Linux 4.15 2018-01-28 13:20:33 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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.