Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 5 Sep 2002 14:48:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 5 Sep 2002 14:48:46 -0400 Received: from vasquez.zip.com.au ([203.12.97.41]:41737 "EHLO vasquez.zip.com.au") by vger.kernel.org with ESMTP id ; Thu, 5 Sep 2002 14:48:46 -0400 Message-ID: <3D77A7A3.FBA1C598@zip.com.au> Date: Thu, 05 Sep 2002 11:51:15 -0700 From: Andrew Morton X-Mailer: Mozilla 4.79 [en] (X11; U; Linux 2.4.19-rc3 i686) X-Accept-Language: en MIME-Version: 1.0 To: Daniel Phillips CC: linux-kernel@vger.kernel.org Subject: Re: Race in shrink_cache References:

<3D770D77.BF85645E@zip.com.au> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1292 Lines: 26 Daniel Phillips wrote: > > .. > On the other hand, if what you want is a private list that page_cache_release > doesn't act on automatically, all you have to do is set the lru state to zero, > leave the page count incremented and move to the private list. You then take > explicit responsibility for freeing the page or moving it back onto a > mainstream lru list. That's the one. Page reclaim speculatively removes a chunk (typically 32) of pages from the LRU, works on them, and puts back any unfreeable ones later on. And the rest of the VM was taught to play correctly with pages that can be off the LRU. This was to avoid hanging onto the LRU lock while running page reclaim. And when those 32 pages are speculatively removed, their refcounts are incremented. Maybe that isn't necessary - I'd need to think about that. If it isn't, then the double-free thing is fixed. If it is necessary then then lru-adds-a-ref approach is nice, because shrink_cache doesn't need to page_cache_get each page while holding the LRU lock, as you say. - 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/