On Mon 13-11-17 07:33:13, Ran Wang wrote: > Hello Michal, > > <snip> > > > Date: Fri, 13 Oct 2017 14:00:12 +0200 > > > > From: Michal Hocko <mhocko@xxxxxxxx> > > > > Michael has noticed that the memory offline tries to migrate kernel code > > pages when doing echo 0 > /sys/devices/system/memory/memory0/online > > > > The current implementation will fail the operation after several failed page > > migration attempts but we shouldn't even attempt to migrate that memory > > and fail right away because this memory is clearly not migrateable. This will > > become a real problem when we drop the retry loop counter resp. timeout. > > > > The real problem is in has_unmovable_pages in fact. We should fail if there > > are any non migrateable pages in the area. In orther to guarantee that > > remove the migrate type checks because MIGRATE_MOVABLE is not > > guaranteed to contain only migrateable pages. It is merely a heuristic. > > Similarly MIGRATE_CMA does guarantee that the page allocator doesn't > > allocate any non-migrateable pages from the block but CMA allocations > > themselves are unlikely to migrateable. Therefore remove both checks. > > > > Reported-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> > > Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> > > Tested-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> > > Acked-by: Vlastimil Babka <vbabka@xxxxxxx> > > --- > > mm/page_alloc.c | 3 --- > > 1 file changed, 3 deletions(-) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c index > > 3badcedf96a7..ad0294ab3e4f 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -7355,9 +7355,6 @@ bool has_unmovable_pages(struct zone *zone, > > struct page *page, int count, > > */ > > if (zone_idx(zone) == ZONE_MOVABLE) > > return false; > > - mt = get_pageblock_migratetype(page); > > - if (mt == MIGRATE_MOVABLE || is_migrate_cma(mt)) > > - return false; > > This drop cause DWC3 USB controller fail on initialization with Layerscaper processors > (such as LS1043A) as below: > > [ 2.701437] xhci-hcd xhci-hcd.0.auto: new USB bus registered, assigned bus number 1 > [ 2.710949] cma: cma_alloc: alloc failed, req-size: 1 pages, ret: -16 > [ 2.717411] xhci-hcd xhci-hcd.0.auto: can't setup: -12 > [ 2.727940] xhci-hcd xhci-hcd.0.auto: USB bus 1 deregistered > [ 2.733607] xhci-hcd: probe of xhci-hcd.0.auto failed with error -12 > [ 2.739978] xhci-hcd xhci-hcd.1.auto: xHCI Host Controller > > And I notice that someone also reported to you that DWC2 got affected recently, > so do you have the solution now? Yes. It should be in linux-next. Have a look at the following email thread: http://lkml.kernel.org/r/20171104082500.qvzbb2kw4suo6cgy@xxxxxxxxxxxxxx -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
