From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx187.postini.com [74.125.245.187]) by kanga.kvack.org (Postfix) with SMTP id CA49E6B0031 for ; Fri, 6 Sep 2013 02:42:08 -0400 (EDT) Message-ID: <5229792F.9000803@oracle.com> Date: Fri, 06 Sep 2013 14:41:51 +0800 From: Bob Liu MIME-Version: 1.0 Subject: Re: [PATCH v2 4/4] mm/zswap: use GFP_NOIO instead of GFP_KERNEL References: <000601ceaac0$5be39f90$13aadeb0$%yang@samsung.com> In-Reply-To: <000601ceaac0$5be39f90$13aadeb0$%yang@samsung.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Weijie Yang Cc: sjenning@linux.vnet.ibm.com, minchan@kernel.org, weijie.yang.kh@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org On 09/06/2013 01:16 PM, Weijie Yang wrote: > To avoid zswap store and reclaim functions called recursively, > use GFP_NOIO instead of GFP_KERNEL > The reason of using GFP_KERNEL in write back path is we want to try our best to move those pages from zswap to real swap device. I think it would be better to keep GFP_KERNEL flag but find some other ways to skip zswap/zswap_frontswap_store() if zswap write back is in progress. What I can think of currently is adding a mutex to zswap, take that mutex when zswap write back happens and check the mutex in zswap_frontswap_store(). > Signed-off-by: Weijie Yang > --- > mm/zswap.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/mm/zswap.c b/mm/zswap.c > index cc40e6a..3d05ed8 100644 > --- a/mm/zswap.c > +++ b/mm/zswap.c > @@ -427,7 +427,7 @@ static int zswap_get_swap_cache_page(swp_entry_t entry, > * Get a new page to read into from swap. > */ > if (!new_page) { > - new_page = alloc_page(GFP_KERNEL); > + new_page = alloc_page(GFP_NOIO); > if (!new_page) > break; /* Out of memory */ > } > @@ -435,7 +435,7 @@ static int zswap_get_swap_cache_page(swp_entry_t entry, > /* > * call radix_tree_preload() while we can wait. > */ > - err = radix_tree_preload(GFP_KERNEL); > + err = radix_tree_preload(GFP_NOIO); > if (err) > break; > > @@ -636,7 +636,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset, > } > > /* allocate entry */ > - entry = zswap_entry_cache_alloc(GFP_KERNEL); > + entry = zswap_entry_cache_alloc(GFP_NOIO); > if (!entry) { > zswap_reject_kmemcache_fail++; > ret = -ENOMEM; > -- Regards, -Bob -- 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: email@kvack.org