Re: [PATCH v3 4/4] memory-hotplug: fix pages missed by race ratherthan failng

[Kamezawa Hiroyuki]

(2012/09/07 9:39), Minchan Kim wrote:
> 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 <mgorman@xxxxxxx>
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>

Sounds reasonable. Thank you very much !

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/