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Michal Hocko 2d070eab2e mm: consider zone which is not fully populated to have holes
__pageblock_pfn_to_page has two users currently, set_zone_contiguous
which checks whether the given zone contains holes and
pageblock_pfn_to_page which then carefully returns a first valid page
from the given pfn range for the given zone.  This doesn't handle zones
which are not fully populated though.  Memory pageblocks can be offlined
or might not have been onlined yet.  In such a case the zone should be
considered to have holes otherwise pfn walkers can touch and play with
offline pages.

Current callers of pageblock_pfn_to_page in compaction seem to work
properly right now because they only isolate PageBuddy
(isolate_freepages_block) or PageLRU resp.  __PageMovable
(isolate_migratepages_block) which will be always false for these pages.
It would be safer to skip these pages altogether, though.

In order to do this patch adds a new memory section state
(SECTION_IS_ONLINE) which is set in memory_present (during boot time) or
in online_pages_range during the memory hotplug.  Similarly
offline_mem_sections clears the bit and it is called when the memory
range is offlined.

pfn_to_online_page helper is then added which check the mem section and
only returns a page if it is onlined already.

Use the new helper in __pageblock_pfn_to_page and skip the whole page
block in such a case.

[mhocko@suse.com: check valid section number in pfn_to_online_page (Vlastimil),
 mark sections online after all struct pages are initialized in
 online_pages_range (Vlastimil)]
  Link: http://lkml.kernel.org/r/20170518164210.GD18333@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/20170515085827.16474-8-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Tobias Regnery <tobias.regnery@gmail.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06 16:24:32 -07:00
arch mm, memory_hotplug: get rid of is_zone_device_section 2017-07-06 16:24:32 -07:00
block Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-07-03 16:50:31 -07:00
certs scripts/spelling.txt: add "intialise(d)" pattern and fix typo instances 2017-05-08 17:15:13 -07:00
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-07-05 12:31:59 -07:00
Documentation ksm: introduce ksm_max_page_sharing per page deduplication limit 2017-07-06 16:24:31 -07:00
drivers mm, memory_hotplug: consider offline memblocks removable 2017-07-06 16:24:32 -07:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs fs/file.c: replace alloc_fdmem() with kvmalloc() alternative 2017-07-06 16:24:30 -07:00
include mm: consider zone which is not fully populated to have holes 2017-07-06 16:24:32 -07:00
init mm: allow slab_nomerge to be set at build time 2017-07-06 16:24:31 -07:00
ipc mm: introduce kv[mz]alloc helpers 2017-05-08 17:15:12 -07:00
kernel kernel/module.c: use linux/set_memory.h 2017-07-06 16:24:30 -07:00
lib Merge branch 'for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2017-07-06 08:59:41 -07:00
mm mm: consider zone which is not fully populated to have holes 2017-07-06 16:24:32 -07:00
net Merge branch 'work.memdup_user' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-05 16:05:24 -07:00
samples bpf: fix return in load_bpf_file 2017-07-05 09:05:28 +01:00
scripts scripts/spelling.txt: add a bunch more spelling mistakes 2017-07-06 16:24:30 -07:00
security Merge branch 'work.memdup_user' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-05 16:05:24 -07:00
sound Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-07-03 13:08:04 -07:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-07-05 12:31:59 -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 arm64 updates for 4.13: 2017-07-05 17:09:27 -07:00
.cocciconfig
.get_maintainer.ignore
.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
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
MAINTAINERS Merge branch 'for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata 2017-07-06 09:41:58 -07:00
Makefile There has been a fair amount of activity in the docs tree this time 2017-07-03 21:13:25 -07:00
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.