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path: root/include/linux/page-isolation.h
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2014-11-13mm/page_alloc: fix incorrect isolation behavior by rechecking migratetypeJoonsoo Kim
Before describing bugs itself, I first explain definition of freepage. 1. pages on buddy list are counted as freepage. 2. pages on isolate migratetype buddy list are *not* counted as freepage. 3. pages on cma buddy list are counted as CMA freepage, too. Now, I describe problems and related patch. Patch 1: There is race conditions on getting pageblock migratetype that it results in misplacement of freepages on buddy list, incorrect freepage count and un-availability of freepage. Patch 2: Freepages on pcp list could have stale cached information to determine migratetype of buddy list to go. This causes misplacement of freepages on buddy list and incorrect freepage count. Patch 4: Merging between freepages on different migratetype of pageblocks will cause freepages accouting problem. This patch fixes it. Without patchset [3], above problem doesn't happens on my CMA allocation test, because CMA reserved pages aren't used at all. So there is no chance for above race. With patchset [3], I did simple CMA allocation test and get below result: - Virtual machine, 4 cpus, 1024 MB memory, 256 MB CMA reservation - run kernel build (make -j16) on background - 30 times CMA allocation(8MB * 30 = 240MB) attempts in 5 sec interval - Result: more than 5000 freepage count are missed With patchset [3] and this patchset, I found that no freepage count are missed so that I conclude that problems are solved. On my simple memory offlining test, these problems also occur on that environment, too. This patch (of 4): There are two paths to reach core free function of buddy allocator, __free_one_page(), one is free_one_page()->__free_one_page() and the other is free_hot_cold_page()->free_pcppages_bulk()->__free_one_page(). Each paths has race condition causing serious problems. At first, this patch is focused on first type of freepath. And then, following patch will solve the problem in second type of freepath. In the first type of freepath, we got migratetype of freeing page without holding the zone lock, so it could be racy. There are two cases of this race. 1. pages are added to isolate buddy list after restoring orignal migratetype CPU1 CPU2 get migratetype => return MIGRATE_ISOLATE call free_one_page() with MIGRATE_ISOLATE grab the zone lock unisolate pageblock release the zone lock grab the zone lock call __free_one_page() with MIGRATE_ISOLATE freepage go into isolate buddy list, although pageblock is already unisolated This may cause two problems. One is that we can't use this page anymore until next isolation attempt of this pageblock, because freepage is on isolate buddy list. The other is that freepage accouting could be wrong due to merging between different buddy list. Freepages on isolate buddy list aren't counted as freepage, but ones on normal buddy list are counted as freepage. If merge happens, buddy freepage on normal buddy list is inevitably moved to isolate buddy list without any consideration of freepage accouting so it could be incorrect. 2. pages are added to normal buddy list while pageblock is isolated. It is similar with above case. This also may cause two problems. One is that we can't keep these freepages from being allocated. Although this pageblock is isolated, freepage would be added to normal buddy list so that it could be allocated without any restriction. And the other problem is same as case 1, that it, incorrect freepage accouting. This race condition would be prevented by checking migratetype again with holding the zone lock. Because it is somewhat heavy operation and it isn't needed in common case, we want to avoid rechecking as much as possible. So this patch introduce new variable, nr_isolate_pageblock in struct zone to check if there is isolated pageblock. With this, we can avoid to re-check migratetype in common case and do it only if there is isolated pageblock or migratetype is MIGRATE_ISOLATE. This solve above mentioned problems. Changes from v3: Add one more check in free_one_page() that checks whether migratetype is MIGRATE_ISOLATE or not. Without this, abovementioned case 1 could happens. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Nazarewicz <mina86@mina86.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Laura Abbott <lauraa@codeaurora.org> Cc: Heesub Shin <heesub.shin@samsung.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Ritesh Harjani <ritesh.list@gmail.com> Cc: Gioh Kim <gioh.kim@lge.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-23mm: remove MIGRATE_ISOLATE check in hotpathMinchan Kim
Several functions test MIGRATE_ISOLATE and some of those are hotpath but MIGRATE_ISOLATE is used only if we enable CONFIG_MEMORY_ISOLATION(ie, CMA, memory-hotplug and memory-failure) which are not common config option. So let's not add unnecessary overhead and code when we don't enable CONFIG_MEMORY_ISOLATION. Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-11memory-hotplug: skip HWPoisoned page when offlining pagesWen Congyang
hwpoisoned may be set when we offline a page by the sysfs interface /sys/devices/system/memory/soft_offline_page or /sys/devices/system/memory/hard_offline_page. If we don't clear this flag when onlining pages, this page can't be freed, and will not in free list. So we can't offline these pages again. So we should skip such page when offlining pages. Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Len Brown <len.brown@intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Christoph Lameter <cl@linux.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andi Kleen <andi@firstfloor.org> 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>
2012-10-09mm/page_alloc: refactor out __alloc_contig_migrate_alloc()Minchan Kim
__alloc_contig_migrate_alloc() can be used by memory-hotplug so refactor it out (move + rename as a common name) into page_isolation.c. [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Acked-by: Michal Nazarewicz <mina86@mina86.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Wen Congyang <wency@cn.fujitsu.com> 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>
2012-10-09memory-hotplug: fix pages missed by race rather than failingMinchan Kim
If race between allocation and isolation in memory-hotplug offline happens, some pages could be in MIGRATE_MOVABLE of free_list although the pageblock's migratetype of the page is MIGRATE_ISOLATE. The race could be detected by get_freepage_migratetype in __test_page_isolated_in_pageblock. If it is detected, now EBUSY gets bubbled all the way up and the hotplug operations fails. But better idea is instead of returning and failing memory-hotremove, move the free page to the correct list at the time it is detected. It could enhance memory-hotremove operation success ratio although the race is really rare. Suggested by Mel Gorman. [akpm@linux-foundation.org: small cleanup] Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31mm: factor out memory isolate functionsMinchan Kim
mm/page_alloc.c has some memory isolation functions but they are used only when we enable CONFIG_{CMA|MEMORY_HOTPLUG|MEMORY_FAILURE}. So let's make it configurable by new CONFIG_MEMORY_ISOLATION so that it can reduce binary size and we can check it simple by CONFIG_MEMORY_ISOLATION, not if defined CONFIG_{CMA|MEMORY_HOTPLUG|MEMORY_FAILURE}. Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Andi Kleen <andi@firstfloor.org> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-21mm: page_isolation: MIGRATE_CMA isolation functions addedMichal Nazarewicz
This commit changes various functions that change pages and pageblocks migrate type between MIGRATE_ISOLATE and MIGRATE_MOVABLE in such a way as to allow to work with MIGRATE_CMA migrate type. Signed-off-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Tested-by: Rob Clark <rob.clark@linaro.org> Tested-by: Ohad Ben-Cohen <ohad@wizery.com> Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> Tested-by: Robert Nelson <robertcnelson@gmail.com> Tested-by: Barry Song <Baohua.Song@csr.com>
2007-10-16memory unplug: page isolationKAMEZAWA Hiroyuki
Implement generic chunk-of-pages isolation method by using page grouping ops. This patch add MIGRATE_ISOLATE to MIGRATE_TYPES. By this - MIGRATE_TYPES increases. - bitmap for migratetype is enlarged. pages of MIGRATE_ISOLATE migratetype will not be allocated even if it is free. By this, you can isolated *freed* pages from users. How-to-free pages is not a purpose of this patch. You may use reclaim and migrate codes to free pages. If start_isolate_page_range(start,end) is called, - migratetype of the range turns to be MIGRATE_ISOLATE if its type is MIGRATE_MOVABLE. (*) this check can be updated if other memory reclaiming works make progress. - MIGRATE_ISOLATE is not on migratetype fallback list. - All free pages and will-be-freed pages are isolated. To check all pages in the range are isolated or not, use test_pages_isolated(), To cancel isolation, use undo_isolate_page_range(). Changes V6 -> V7 - removed unnecessary #ifdef There are HOLES_IN_ZONE handling codes...I'm glad if we can remove them.. Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com> Signed-off-by: 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>