From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Date: Tue, 12 Aug 2008 15:35:14 +1000 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <18593.8466.965002.476705@notabene.brown> Subject: Re: [PATCH 05/30] mm: slb: add knowledge of reserve pages In-Reply-To: message from Peter Zijlstra on Thursday July 24 References: <20080724140042.408642539@chello.nl> <20080724141529.635920366@chello.nl> Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, trond.myklebust@fys.uio.no, Daniel Lezcano , Pekka Enberg List-ID: On Thursday July 24, a.p.zijlstra@chello.nl wrote: > Restrict objects from reserve slabs (ALLOC_NO_WATERMARKS) to allocation > contexts that are entitled to it. This is done to ensure reserve pages don't > leak out and get consumed. This looks good (we are still missing slob though, aren't we :-( ) > @@ -1526,7 +1540,7 @@ load_freelist: > object = c->page->freelist; > if (unlikely(!object)) > goto another_slab; > - if (unlikely(SLABDEBUG && PageSlubDebug(c->page))) > + if (unlikely(PageSlubDebug(c->page) || c->reserve)) > goto debug; This looks suspiciously like debugging code that you have left in. Is it?? > @@ -265,7 +267,8 @@ struct array_cache { > unsigned int avail; > unsigned int limit; > unsigned int batchcount; > - unsigned int touched; > + unsigned int touched:1, > + reserve:1; This sort of thing always worries me. It is a per-cpu data structure so you won't get SMP races corrupting fields. But you do get read-modify-write in place of simple updates. I guess it's not a problem.. But it worries me :-) NeilBrown -- 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