linux-kernel - Re: linux-next: Tree for Nov 27 (mm stuff)

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Date:	Fri, 27 Nov 2015 13:16:40 +0300
From:	Vladimir Davydov <vdavydov@...tuozzo.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
CC:	Randy Dunlap <rdunlap@...radead.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	<linux-next@...r.kernel.org>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	<linux-kernel@...r.kernel.org>, Linux MM <linux-mm@...ck.org>
Subject: Re: linux-next: Tree for Nov 27 (mm stuff)

On Fri, Nov 27, 2015 at 06:17:39PM +0900, Sergey Senozhatsky wrote:
> Cc Vladimir, Kirill, Andrew
> 
> On (11/27/15 18:10), Sergey Senozhatsky wrote:
> > On (11/26/15 23:04), Randy Dunlap wrote:
> > > 
> > > on i386:
> > > 
> > > mm/built-in.o: In function `page_referenced_one':
> > > rmap.c:(.text+0x362a2): undefined reference to `pmdp_clear_flush_young'
> > > mm/built-in.o: In function `page_idle_clear_pte_refs_one':
> > > page_idle.c:(.text+0x4b2b8): undefined reference to `pmdp_test_and_clear_young'
> > > 
> > 
> > Hello,
> > 
> > https://lkml.org/lkml/2015/11/24/160
> > 
> > corresponding patch mm-add-page_check_address_transhuge-helper-fix.patch added
> > to -mm tree.
> > 
> 
> my bad, it's in -next already.

Sigh, this fails for me too :-( Kirill was right that this hack might
not always work.

So, we still need to check explicitly if CONFIG_TRANSPARENT_HUGEPAGE is
enabled whenever we use page_check_address_transhuge, as Kirill proposed
initially. The patch below does the trick. The previous "fix" is still
useful though, because it reduces the size of kernels compiled w/o
tranparent huge page feature.

Andrew, could you please merge this patch too?

Sorry for all the trouble.

Thanks,
Vladimir
---
diff --git a/mm/page_idle.c b/mm/page_idle.c
index 374931f..aa7ca61 100644
--- a/mm/page_idle.c
+++ b/mm/page_idle.c
@@ -66,7 +66,7 @@ static int page_idle_clear_pte_refs_one(struct page *page,
 	if (pte) {
 		referenced = ptep_clear_young_notify(vma, addr, pte);
 		pte_unmap(pte);
-	} else
+	} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
 		referenced = pmdp_clear_young_notify(vma, addr, pmd);
 
 	spin_unlock(ptl);
diff --git a/mm/rmap.c b/mm/rmap.c
index 6f37126..3286d49 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -931,7 +931,7 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
 				referenced++;
 		}
 		pte_unmap(pte);
-	} else {
+	} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
 		if (pmdp_clear_flush_young_notify(vma, address, pmd))
 			referenced++;
 	}
--
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