From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx122.postini.com [74.125.245.122]) by kanga.kvack.org (Postfix) with SMTP id 047FB6B0031 for ; Wed, 24 Jul 2013 12:37:37 -0400 (EDT) Received: by mail-la0-f54.google.com with SMTP id ec20so514354lab.27 for ; Wed, 24 Jul 2013 09:37:36 -0700 (PDT) Date: Wed, 24 Jul 2013 20:37:34 +0400 From: Cyrill Gorcunov Subject: Re: [PATCH] mm: Save soft-dirty bits on swapped pages Message-ID: <20130724163734.GE24851@moon> References: <20130724160826.GD24851@moon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Andy Lutomirski Cc: Linux MM , LKML , Pavel Emelyanov , Andrew Morton , Matt Mackall , Xiao Guangrong , Marcelo Tosatti , KOSAKI Motohiro , Stephen Rothwell On Wed, Jul 24, 2013 at 09:23:14AM -0700, Andy Lutomirski wrote: > On Wed, Jul 24, 2013 at 9:08 AM, Cyrill Gorcunov wrote: > > Andy Lutomirski reported that in case if a page with _PAGE_SOFT_DIRTY > > bit set get swapped out, the bit is getting lost and no longer > > available when pte read back. > > Potentially silly question (due to my completely lack of understanding > of how swapping works in Linux): what about file-backed pages? > (Arguably these would be best supported by filesystems instead of by > the core vm, in which case it might make sense to drop soft-dirty > support for these pages entirely.) Hi Andy, if I understand you correctly "file-backed pages" are carried in pte with _PAGE_FILE bit set and the swap soft-dirty bit won't be used on them but _PAGE_SOFT_DIRTY will be set on write if only I've not missed something obvious (Pavel?). -- 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