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Date: Thu, 28 May 2009 10:44:48 +0900 From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> To: Daisuke Nishimura <nishimura@....nes.nec.co.jp> Cc: "linux-mm@...ck.org" <linux-mm@...ck.org>, "balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>, "hugh.dickins@...cali.co.uk" <hugh.dickins@...cali.co.uk>, "hannes@...xchg.org" <hannes@...xchg.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [RFC][PATCH 2/5] add SWAP_HAS_CACHE flag to swap_map On Thu, 28 May 2009 10:40:13 +0900 Daisuke Nishimura <nishimura@....nes.nec.co.jp> wrote: > > > So I think it should be like: > > > > > > read_swap_cache_async() > > > : > > > valid = swapcache_prepare(entry); > > > if (!valid) > > > break; > > > if (valid == -EAGAIN); > > > continue; > > > > > > to let the context that succeeded in swapcache_prepare() do add_to_swap_cache(). > > > > > > > What you reccomend is code like this ? > > > > == > > ret = swapcache_prapare(entry); > > if (ret == -ENOENT) > > break; /* unused swap entry */ > > if (ret == -EBUSY) > > continue; /* to call find_get_page() again */ > > == > > > Yes. > By current version of your patch, read_swap_cache_async() might return NULL > if concurrent read_swap_cache_async() exists. It is different from current behavior. > And this means swapin_readahead() might fail(it calls read_swap_cache_async() > twice, though) and can cause oom, right ? > Good point. I fixed this in a patch in my box ;) Thank you fot good review. Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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