Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754641AbbKMMBV (ORCPT ); Fri, 13 Nov 2015 07:01:21 -0500 Received: from mx2.suse.de ([195.135.220.15]:38774 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753250AbbKMMBT (ORCPT ); Fri, 13 Nov 2015 07:01:19 -0500 Subject: Re: [PATCH] mm: change may_enter_fs check condition To: yalin wang , akpm@linux-foundation.org, mhocko@suse.cz, vdavydov@parallels.com, hannes@cmpxchg.org, mgorman@techsingularity.net, tj@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1447415255-832-1-git-send-email-yalin.wang2010@gmail.com> From: Vlastimil Babka Message-ID: <5645D10C.701@suse.cz> Date: Fri, 13 Nov 2015 13:01:16 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <1447415255-832-1-git-send-email-yalin.wang2010@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1539 Lines: 39 On 11/13/2015 12:47 PM, yalin wang wrote: > Add page_is_file_cache() for __GFP_FS check, > otherwise, a Pageswapcache() && PageDirty() page can always be write > back if the gfp flag is __GFP_FS, this is not the expected behavior. I'm not sure I understand your point correctly *), but you seem to imply that there would be an allocation that has __GFP_FS but doesn't have __GFP_IO? Are there such allocations and does it make sense? *) It helps to state which problem you actually observed and are trying to fix. Or was this found by code inspection? In that case describe the theoretical problem, as "expected behavior" isn't always understood by everyone the same. > Signed-off-by: yalin wang > --- > mm/vmscan.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index bd2918e..f8fc8c1 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -930,7 +930,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, > if (page_mapped(page) || PageSwapCache(page)) > sc->nr_scanned++; > > - may_enter_fs = (sc->gfp_mask & __GFP_FS) || > + may_enter_fs = (page_is_file_cache(page) && (sc->gfp_mask & __GFP_FS)) || > (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); > > /* > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/