From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f70.google.com (mail-lf0-f70.google.com [209.85.215.70]) by kanga.kvack.org (Postfix) with ESMTP id D47006B0038 for ; Thu, 26 Jan 2017 12:09:45 -0500 (EST) Received: by mail-lf0-f70.google.com with SMTP id v186so98645401lfa.2 for ; Thu, 26 Jan 2017 09:09:45 -0800 (PST) Received: from mail-lf0-x244.google.com (mail-lf0-x244.google.com. [2a00:1450:4010:c07::244]) by mx.google.com with ESMTPS id 84si1280268lfp.363.2017.01.26.09.09.44 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 26 Jan 2017 09:09:44 -0800 (PST) Received: by mail-lf0-x244.google.com with SMTP id q89so24168695lfi.1 for ; Thu, 26 Jan 2017 09:09:44 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <2059ec0c-d817-9660-9a16-59fe46f3e3a7@samsung.com> References: <20170117122249.815342d95117c3f444acc952@linux-foundation.org> <20170118013948.GA580@jagdpanzerIV.localdomain> <1484719121.25232.1.camel@list.ru> <1485216185.5952.2.camel@list.ru> <2059ec0c-d817-9660-9a16-59fe46f3e3a7@samsung.com> From: Dan Streetman Date: Thu, 26 Jan 2017 12:09:03 -0500 Message-ID: Subject: Re: [Bug 192571] zswap + zram enabled BUG Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Chulmin Kim Cc: Alexandr , bugzilla-daemon@bugzilla.kernel.org, Linux-MM On Tue, Jan 24, 2017 at 11:02 PM, Chulmin Kim wrote: > On 01/24/2017 03:16 PM, Dan Streetman wrote: >> >> On Mon, Jan 23, 2017 at 7:03 PM, Alexandr wrote: >>> >>> -----BEGIN PGP SIGNED MESSAGE----- >>> Hash: SHA512 >>> >>> >>>> Why would you do this? There's no benefit of using zswap together >>>> with zram. >>> >>> >>> i just wanted to test zram and zswap, i still not dig to deep in it, >>> but what i wanted is to use zram swap (with zswap disabled), and if it >>> exceeded use real swap on block device with zswap enabled. >> >> >> I don't believe that's possible, you can't enable zswap for only >> specific swap devices; and anyway, if you fill up zram, you won't >> really have any memory left for zswap to use will you? >> >> However, it shouldn't encounter any BUG(), like you saw. If it's >> reproducable for you, can you give details on how to reproduce it? >> > > Hello. Mr. Streetman. > > > Regarding to this problem, I have a question on zswap. > > Is there any reason that > zswap_frontswap_load() does not call flush_dcache_page()? > > The zswap load function can dirty the page mapped to user space (might be > shareable/writable) which seems exactly the condition mentioned in the > definition of flush_dcache_page(). > > I'm thinking that > flush_dcache_page() should be called in the end of zswap_frontswap_load(). > Could you review my opinion? I don't think it needs to, as i detailed in my response to the other thread. Also, this is a different issue, I think - even if there is a cache problem with pages loaded from zswap, i don't see how it would cause a decompression failure - the zpool storage is the only code that has a copy of its compressed pages, no userspace or any other kernel code should be accessing any of it. > > Thanks! > Chulmin Kim > > > > > > > > > >> -- >> 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 >> >> > > -- > 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 > -- 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