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Date: Fri, 01 Aug 2014 09:12:06 +0900 From: Gioh Kim <gioh.kim@....com> To: Andrew Morton <akpm@...ux-foundation.org> CC: '김준수' <iamjoonsoo.kim@....com>, Marek Szyprowski <m.szyprowski@...sung.com>, Minchan Kim <minchan@...nel.org>, Laura Abbott <lauraa@...eaurora.org>, Michal Nazarewicz <mina86@...a86.com>, Alexander Viro <viro@...iv.linux.org.uk>, Johannes Weiner <hannes@...xchg.org>, linux-kernel@...r.kernel.org, linux-mm@...ck.org, ????????? <gunho.lee@....com>, 'Chanho Min' <chanho.min@....com> Subject: Re: [PATCHv2] CMA/HOTPLUG: clear buffer-head lru before page migration 2014-08-01 오전 7:57, Andrew Morton 쓴 글: > On Thu, 31 Jul 2014 11:22:35 +0900 Gioh Kim <gioh.kim@....com> wrote: > >> The previous PATCH inserts invalidate_bh_lrus() only into CMA code. >> HOTPLUG needs also dropping bh of lru. >> So v2 inserts invalidate_bh_lrus() into both of CMA and HOTPLUG. >> >> >> ---------------------------- 8< ---------------------------- >> The bh must be free to migrate a page at which bh is mapped. >> The reference count of bh is increased when it is installed >> into lru so that the bh of lru must be freed before migrating the page. >> >> This frees every bh of lru. We could free only bh of migrating page. >> But searching lru sometimes costs more than invalidating entire lru. >> >> Signed-off-by: Gioh Kim <gioh.kim@....com> >> Acked-by: Michal Nazarewicz <mina86@...a86.com> >> --- >> mm/memory_hotplug.c | 1 + >> mm/page_alloc.c | 2 ++ >> 2 files changed, 3 insertions(+) >> >> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >> index a3797d3..1c5454f 100644 >> --- a/mm/memory_hotplug.c >> +++ b/mm/memory_hotplug.c >> @@ -1672,6 +1672,7 @@ repeat: >> lru_add_drain_all(); >> cond_resched(); >> drain_all_pages(); >> + invalidate_bh_lrus(); > > Both of these calls should have a comment explaining why > invalidate_bh_lrus() is being called. > >> } >> >> pfn = scan_movable_pages(start_pfn, end_pfn); >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index b99643d4..c00dedf 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -6369,6 +6369,8 @@ int alloc_contig_range(unsigned long start, unsigned long end, >> if (ret) >> return ret; >> >> + invalidate_bh_lrus(); >> + >> ret = __alloc_contig_migrate_range(&cc, start, end); >> if (ret) >> goto done; > > I do feel that this change is likely to be beneficial, but I don't want > to apply such a patch until I know what its effects are upon all > alloc_contig_range() callers. Especially hugetlb. I'm very sorry to hear that. How can I check the effects? > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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