From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 25 Jun 1999 00:23:26 +0200 (CEST) From: Andrea Arcangeli Subject: Re: filecache/swapcache questions In-Reply-To: <199906212344.QAA93017@google.engr.sgi.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Kanoj Sarcar Cc: sct@redhat.com, linux-mm@kvack.org List-ID: On Mon, 21 Jun 1999, Kanoj Sarcar wrote: >And continuing on with the problems with swapoff ... I have not thought yet at the races you are talking about in the thread. But I think I seen another potential problem related to swapoff in the last days. Think if you run swapoff -a while there is a program that is faulting in a swapin exception. The process is sleeping into read_swap_cache_async() after having increased the swap-count (this is the only problem). While the task is sleeping swapoff will swapin the page and will map the swapped-in page in the pte of the process while the process is sleeping. Then swapoff continue and see that the swap-count is still > 0 (1 in the example) even if the page is been swapped-in for all tasks in the system. Swapoff get confused and set the swap count to 0 by hand (and doing that it corrupts a bit the state of the VM). I think I reproduced the above scenario stress testing 2.3.8 + my VM changes (finally "stable" except the buffer beyond end of the device problem) but it the problem I seen is real then it will apply to 2.2.x as well. Andrea Arcangeli -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://humbolt.geo.uu.nl/Linux-MM/