When hotplug offlining happens on zone A, it starts to mark freed page as
MIGRATE_ISOLATE type in buddy for preventing further allocation.
(MIGRATE_ISOLATE is very irony type because it's apparently on buddy but
we can't allocate them).
When the memory shortage happens during hotplug offlining, current task
starts to reclaim, then wake up kswapd. Kswapd checks watermark, then go
sleep because current zone_watermark_ok_safe doesn't consider
MIGRATE_ISOLATE freed page count. Current task continue to reclaim in
direct reclaim path without kswapd's helping. The problem is that
zone->all_unreclaimable is set by only kswapd so that current task would
be looping forever like below.
__alloc_pages_slowpath
restart:
wake_all_kswapd
rebalance:
__alloc_pages_direct_reclaim
do_try_to_free_pages
if global_reclaim && !all_unreclaimable
return 1; /* It means we did did_some_progress */
skip __alloc_pages_may_oom
should_alloc_retry
goto rebalance;
If we apply KOSAKI's patch[1] which doesn't depends on kswapd about
setting zone->all_unreclaimable, we can solve this problem by killing some
task in direct reclaim path. But it doesn't wake up kswapd, still. It
could be a problem still if other subsystem needs GFP_ATOMIC request. So
kswapd should consider MIGRATE_ISOLATE when it calculate free pages BEFORE
going sleep.
This patch counts the number of MIGRATE_ISOLATE page block and
zone_watermark_ok_safe will consider it if the system has such blocks
(fortunately, it's very rare so no problem in POV overhead and kswapd is
never hotpath).
Copy/modify from Mel's quote
"
Ideal solution would be "allocating" the pageblock.
It would keep the free space accounting as it is but historically,
memory hotplug didn't allocate pages because it would be difficult to
detect if a pageblock was isolated or if part of some balloon.
Allocating just full pageblocks would work around this, However,
it would play very badly with CMA.
"
[1] http://lkml.org/lkml/2012/6/14/74
[akpm@linux-foundation.org: simplify nr_zone_isolate_freepages(), rework zone_watermark_ok_safe() comment, simplify set_pageblock_isolate() and restore_pageblock_isolate()]
[akpm@linux-foundation.org: fix CONFIG_MEMORY_ISOLATION=n build]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Suggested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Tested-by: Aaditya Kumar <aaditya.kumar.30@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@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>
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>
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>
__test_page_isolated_in_pageblock() returns 1 if all pages in the range
are isolated, so fix the comment. Variable `pfn' will be initialised in
the following loop so remove it.
Signed-off-by: Bob Liu <lliubbo@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.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>
My last bugfix here (adding zone->lock) introduced a new problem: Using
page_zone(pfn_to_page(pfn)) to get the zone after the for() loop is wrong.
pfn will then be >= end_pfn, which may be in a different zone or not
present at all. This may lead to an addressing exception in page_zone()
or spin_lock_irqsave().
Now I use __first_valid_page() again after the loop to find a valid page
for page_zone().
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Acked-by: Nathan Fontenot <nfont@austin.ibm.com>
Reviewed-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>
__test_page_isolated_in_pageblock() in mm/page_isolation.c has a comment
saying that the caller must hold zone->lock. But the only caller of that
function, test_pages_isolated(), does not hold zone->lock and the lock is
also not acquired anywhere before. This patch adds the missing zone->lock
to test_pages_isolated().
We reproducibly run into BUG_ON(!PageBuddy(page)) in __offline_isolated_pages()
during memory hotplug stress test, see trace below. This patch fixes that
problem, it would be good if we could have it in 2.6.27.
kernel BUG at /home/autobuild/BUILD/linux-2.6.26-20080909/mm/page_alloc.c:4561!
illegal operation: 0001 [#1] PREEMPT SMP
Modules linked in: dm_multipath sunrpc bonding qeth_l3 dm_mod qeth ccwgroup vmur
CPU: 1 Not tainted 2.6.26-29.x.20080909-s390default #1
Process memory_loop_all (pid: 10025, task: 2f444028, ksp: 2b10dd28)
Krnl PSW : 040c0000 801727ea (__offline_isolated_pages+0x18e/0x1c4)
R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:0 CC:0 PM:0
Krnl GPRS: 00000000 7e27fc00 00000000 7e27fc00
00000000 00000400 00014000 7e27fc01
00606f00 7e27fc00 00013fe0 2b10dd28
00000005 80172662 801727b2 2b10dd28
Krnl Code: 801727de: 5810900c l %r1,12(%r9)
801727e2: a7f4ffb3 brc 15,80172748
801727e6: a7f40001 brc 15,801727e8
>801727ea: a7f4ffbc brc 15,80172762
801727ee: a7f40001 brc 15,801727f0
801727f2: a7f4ffaf brc 15,80172750
801727f6: 0707 bcr 0,%r7
801727f8: 0017 unknown
Call Trace:
([<0000000000172772>] __offline_isolated_pages+0x116/0x1c4)
[<00000000001953a2>] offline_isolated_pages_cb+0x22/0x34
[<000000000013164c>] walk_memory_resource+0xcc/0x11c
[<000000000019520e>] offline_pages+0x36a/0x498
[<00000000001004d6>] remove_memory+0x36/0x44
[<000000000028fb06>] memory_block_change_state+0x112/0x150
[<000000000028ffb8>] store_mem_state+0x90/0xe4
[<0000000000289c00>] sysdev_store+0x34/0x40
[<00000000001ee048>] sysfs_write_file+0xd0/0x178
[<000000000019b1a8>] vfs_write+0x74/0x118
[<000000000019b9ae>] sys_write+0x46/0x7c
[<000000000011160e>] sysc_do_restart+0x12/0x16
[<0000000077f3e8ca>] 0x77f3e8ca
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Acked-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>
We should unset migrate type "ISOLATE" when we successfully removed memory.
But current code has BUG and cannot works well.
This patch also includes bugfix? to change get_pageblock_flags to
get_pageblock_migratetype().
Thanks to Badari Pulavarty for finding this.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
Minchan Kim