From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 41855900117 for ; Tue, 4 Oct 2011 06:11:22 -0400 (EDT) Date: Tue, 4 Oct 2011 12:10:36 +0200 From: Johannes Weiner Subject: Re: [patch] mm: disable user interface to manually rescue unevictable pages Message-ID: <20111004101036.GB1687@redhat.com> References: <1316948380-1879-1-git-send-email-consul.kautuk@gmail.com> <20110926112944.GC14333@redhat.com> <20110926161136.b4508ecb.akpm@google.com> <20110927072714.GA1997@redhat.com> <20110928021424.GA2715@barrios-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110928021424.GA2715@barrios-desktop> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Andrew Morton , Kautuk Consul , Mel Gorman , KAMEZAWA Hiroyuki , Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Lee Schermerhorn , KOSAKI Motohiro , Andrew Morton On Wed, Sep 28, 2011 at 11:14:24AM +0900, Minchan Kim wrote: > On Tue, Sep 27, 2011 at 09:27:14AM +0200, Johannes Weiner wrote: > > At one point, anonymous pages were supposed to go on the unevictable > > list when no swap space was configured, and the idea was to manually > > rescue those pages after adding swap and making them evictable again. > > But nowadays, swap-backed pages on the anon LRU list are not scanned > > without available swap space anyway, so there is no point in moving > > them to a separate list anymore. > > > > The manual rescue could also be used in case pages were stranded on > > the unevictable list due to race conditions. But the code has been > > around for a while now and newly discovered bugs should be properly > > reported and dealt with instead of relying on such a manual fixup. > > > > In addition to the lack of a usecase, the sysfs interface to rescue > > pages from a specific NUMA node has been broken since its > > introduction, so it's unlikely that anybody ever relied on that. > > > > This patch removes the functionality behind the sysctl and the > > node-interface and emits a one-time warning when somebody tries to > > access either of them. > > > > Signed-off-by: Johannes Weiner > > Reported-by: Kautuk Consul > Reviewed-by: Minchan Kim Thanks, Minchan. > > @@ -3469,11 +3415,8 @@ int scan_unevictable_handler(struct ctl_table *table, int write, > > void __user *buffer, > > size_t *length, loff_t *ppos) > > { > > + warn_scan_unevictable_pages(); > > proc_doulongvec_minmax(table, write, buffer, length, ppos); > > - > > - if (write && *(unsigned long *)table->data) > > - scan_all_zones_unevictable_pages(); > > - > > scan_unevictable_pages = 0; > > Nitpick: > Could we remove this resetting with zero? table->data = &scan_unevictable_pages, so I let it in such that the generic sysctl stuff to process the input and clean up afterward is complete. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org