From: Chen Gang <gang.chen@asianux.com> To: Mel Gorman <mgorman@suse.de> Cc: hannes@cmpxchg.org, riel@redhat.com, mhocko@suse.cz, Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org> Subject: Re: [PATCH] mm/vmscan.c: 'lru' may be used without initialized after the patch "3abf380..." in next-20130607 tree Date: Wed, 19 Jun 2013 17:56:33 +0800 [thread overview] Message-ID: <51C18051.8070404@asianux.com> (raw) In-Reply-To: <20130619085315.GK1875@suse.de> On 06/19/2013 04:53 PM, Mel Gorman wrote: > On Wed, Jun 19, 2013 at 02:55:13PM +0800, Chen Gang wrote: >> > >> > 'lru' may be used without initialized, so need regressing part of the >> > related patch. >> > >> > The related patch: >> > "3abf380 mm: remove lru parameter from __lru_cache_add and lru_cache_add_lru" >> > >> > >> > Signed-off-by: Chen Gang <gang.chen@asianux.com> >> > --- >> > mm/vmscan.c | 1 + >> > 1 files changed, 1 insertions(+), 0 deletions(-) >> > >> > diff --git a/mm/vmscan.c b/mm/vmscan.c >> > index fe73724..e92b1858 100644 >> > --- a/mm/vmscan.c >> > +++ b/mm/vmscan.c >> > @@ -595,6 +595,7 @@ redo: >> > * unevictable page on [in]active list. >> > * We know how to handle that. >> > */ >> > + lru = !!TestClearPageActive(page) + page_lru_base_type(page); >> > lru_cache_add(page); > Thanks for catching this but I have one question. Why are you clearing > the active bit? > Oh, it is my fault, I only want to regress part of the original patch, did not notice clearing the active bit. > Before 3abf380 we did > > active = TestClearPageActive(page); > lru = active + page_lru_base_type(page); > lru_cache_add_lru(page, lru); > > so if the page was active before then it gets added to the active list. When > 3abf380 is applied. it becomes. > > Leave PageActive alone > lru_cache_add(page); > .... until __pagevec_lru_add -> __pagevec_lru_add_fn > int file = page_is_file_cache(page); > int active = PageActive(page); > enum lru_list lru = page_lru(page); > > After your patch it's > > Clear PageActive > lru_cache_add(page) > ...... > always add to inactive list > > I do not think you intended to do this and if you did, it deserves far > more comment than being a compile warning fix. In putback_lru_page we only > care about whether the lru was unevictable or not. Hence I think what you > meant to do was simply > > lru = page_lru_base_type(page); > > If you agree then can you resend a revised version to Andrew please? Yes, I should do, but excuse me, I do not quite know about 'revised version'. I guess it means I need still send the related patch which base on the original one, e.g. for next-20130618: ------------------------diff begin------------------------------------- diff --git a/mm/vmscan.c b/mm/vmscan.c index fe73724..d03facb 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -595,6 +595,7 @@ redo: * unevictable page on [in]active list. * We know how to handle that. */ + lru = page_lru_base_type(page); lru_cache_add(page); } else { /* ------------------------diff end--------------------------------------- Is it correct ? Thanks. -- Chen Gang Asianux Corporation
WARNING: multiple messages have this Message-ID (diff)
From: Chen Gang <gang.chen@asianux.com> To: Mel Gorman <mgorman@suse.de> Cc: hannes@cmpxchg.org, riel@redhat.com, mhocko@suse.cz, Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org> Subject: Re: [PATCH] mm/vmscan.c: 'lru' may be used without initialized after the patch "3abf380..." in next-20130607 tree Date: Wed, 19 Jun 2013 17:56:33 +0800 [thread overview] Message-ID: <51C18051.8070404@asianux.com> (raw) In-Reply-To: <20130619085315.GK1875@suse.de> On 06/19/2013 04:53 PM, Mel Gorman wrote: > On Wed, Jun 19, 2013 at 02:55:13PM +0800, Chen Gang wrote: >> > >> > 'lru' may be used without initialized, so need regressing part of the >> > related patch. >> > >> > The related patch: >> > "3abf380 mm: remove lru parameter from __lru_cache_add and lru_cache_add_lru" >> > >> > >> > Signed-off-by: Chen Gang <gang.chen@asianux.com> >> > --- >> > mm/vmscan.c | 1 + >> > 1 files changed, 1 insertions(+), 0 deletions(-) >> > >> > diff --git a/mm/vmscan.c b/mm/vmscan.c >> > index fe73724..e92b1858 100644 >> > --- a/mm/vmscan.c >> > +++ b/mm/vmscan.c >> > @@ -595,6 +595,7 @@ redo: >> > * unevictable page on [in]active list. >> > * We know how to handle that. >> > */ >> > + lru = !!TestClearPageActive(page) + page_lru_base_type(page); >> > lru_cache_add(page); > Thanks for catching this but I have one question. Why are you clearing > the active bit? > Oh, it is my fault, I only want to regress part of the original patch, did not notice clearing the active bit. > Before 3abf380 we did > > active = TestClearPageActive(page); > lru = active + page_lru_base_type(page); > lru_cache_add_lru(page, lru); > > so if the page was active before then it gets added to the active list. When > 3abf380 is applied. it becomes. > > Leave PageActive alone > lru_cache_add(page); > .... until __pagevec_lru_add -> __pagevec_lru_add_fn > int file = page_is_file_cache(page); > int active = PageActive(page); > enum lru_list lru = page_lru(page); > > After your patch it's > > Clear PageActive > lru_cache_add(page) > ...... > always add to inactive list > > I do not think you intended to do this and if you did, it deserves far > more comment than being a compile warning fix. In putback_lru_page we only > care about whether the lru was unevictable or not. Hence I think what you > meant to do was simply > > lru = page_lru_base_type(page); > > If you agree then can you resend a revised version to Andrew please? Yes, I should do, but excuse me, I do not quite know about 'revised version'. I guess it means I need still send the related patch which base on the original one, e.g. for next-20130618: ------------------------diff begin------------------------------------- diff --git a/mm/vmscan.c b/mm/vmscan.c index fe73724..d03facb 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -595,6 +595,7 @@ redo: * unevictable page on [in]active list. * We know how to handle that. */ + lru = page_lru_base_type(page); lru_cache_add(page); } else { /* ------------------------diff end--------------------------------------- Is it correct ? Thanks. -- Chen Gang Asianux Corporation -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2013-06-19 9:57 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-06-19 6:55 [PATCH] mm/vmscan.c: 'lru' may be used without initialized after the patch "3abf380..." in next-20130607 tree Chen Gang 2013-06-19 6:55 ` Chen Gang 2013-06-19 7:10 ` Andrew Morton 2013-06-19 7:10 ` Andrew Morton 2013-06-19 7:19 ` Chen Gang 2013-06-19 7:19 ` Chen Gang 2013-07-05 4:06 ` Chen Gang 2013-07-05 4:06 ` Chen Gang 2013-07-08 6:43 ` Chen Gang 2013-07-08 6:43 ` Chen Gang 2013-07-09 2:16 ` Chen Gang 2013-07-09 2:16 ` Chen Gang 2013-06-19 8:53 ` Mel Gorman 2013-06-19 8:53 ` Mel Gorman 2013-06-19 9:56 ` Chen Gang [this message] 2013-06-19 9:56 ` Chen Gang 2013-06-19 10:25 ` [PATCH v2] " Chen Gang 2013-06-19 10:25 ` Chen Gang
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