Re: [PATCH] [for mmotm-1113] mm: Simplify try_to_unmap_one()

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

> > 
> > 
> > On Thu, 19 Nov 2009, KOSAKI Motohiro wrote:
> > 
> > > > 
> > > > Hi KOSAKI,
> > > > 
> > > > Thank you for the comment, I am still little confused with the last 
> > > > sentence.
> > > > 
> > > > On Thu, 19 Nov 2009, KOSAKI Motohiro wrote:
> > > > 
> > > > > 
> > > > > +
> > > > > +	/*
> > > > > +	 * We need mmap_sem locking, Otherwise VM_LOCKED check makes
> > > > > +	 * unstable result and race. Plus, We can't wait here because
> > > > > +	 * we now hold anon_vma->lock or mapping->i_mmap_lock.
> > > > > +	 * If trylock failed, The page remain evictable lru and
> > > > > +	 * retry to more unevictable lru by later vmscan.
> > > >            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ I am having 
> > > > trouble to undestand it. Yeah, I should read more code, but the sentence 
> > > > itself make me confused :).
> > > 
> > > Um, this is wrong.
> > > Probably, It should be
> > > 
> > > 	retry to move unevictable lru later.
> > > 
> > > Do you agree this?
> > 
> > Ah, let's see if I understand you correctly, if trylock failed, the page 
> > remain in evictable lru and later vmscan could retry to move the page to 
> > unevictable lru if the page is actually mlocked? 
> 
> Ah, your sentence is better. can you please change code itself?

Fix is here.

------------------------------------------
Subject: [PATCH] try_to_unmap_one() comment fix

Viencent Li pointed out current comment is wrong. This patch fixes it.

Reported-by: Vincent Li <macli@brc.ubc.ca>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
---
 mm/rmap.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index f1a9f7d..278cd27 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -875,8 +875,9 @@ out_mlock:
 	 * We need mmap_sem locking, Otherwise VM_LOCKED check makes
 	 * unstable result and race. Plus, We can't wait here because
 	 * we now hold anon_vma->lock or mapping->i_mmap_lock.
-	 * If trylock failed, The page remain evictable lru and
-	 * retry to more unevictable lru by later vmscan.
+	 * if trylock failed, the page remain in evictable lru and later
+	 * vmscan could retry to move the page to unevictable lru if the
+	 * page is actually mlocked.
 	 */
 	if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
 		if (vma->vm_flags & VM_LOCKED) {
-- 
1.6.5.2



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