From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f44.google.com (mail-pb0-f44.google.com [209.85.160.44]) by kanga.kvack.org (Postfix) with ESMTP id E7F786B0031 for ; Wed, 15 Jan 2014 18:02:17 -0500 (EST) Received: by mail-pb0-f44.google.com with SMTP id rq2so1791372pbb.31 for ; Wed, 15 Jan 2014 15:02:17 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTP id j8si5020878pad.265.2014.01.15.15.02.15 for ; Wed, 15 Jan 2014 15:02:16 -0800 (PST) Date: Wed, 15 Jan 2014 15:02:14 -0800 From: Andrew Morton Subject: Re: [PATCH] mm: Make {,set}page_address() static inline if WANT_PAGE_VIRTUAL Message-Id: <20140115150214.d30aa6ab15b02c24b6923821@linux-foundation.org> In-Reply-To: References: <1389778426-14836-1-git-send-email-geert@linux-m68k.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Geert Uytterhoeven , Guenter Roeck , "Michael S. Tsirkin" , linux-mm@kvack.org, linux-bcache@vger.kernel.org, Vineet Gupta , sparclinux@vger.kernel.org, linux-m68k@vger.kernel.org, linux-kernel@vger.kernel.org On Wed, 15 Jan 2014 14:57:56 -0800 (PST) David Rientjes wrote: > On Wed, 15 Jan 2014, Geert Uytterhoeven wrote: > > > {,set}page_address() are macros if WANT_PAGE_VIRTUAL. > > If !WANT_PAGE_VIRTUAL, they're plain C functions. > > > > If someone calls them with a void *, this pointer is auto-converted to > > struct page * if !WANT_PAGE_VIRTUAL, but causes a build failure on > > architectures using WANT_PAGE_VIRTUAL (arc, m68k and sparc): > > s/sparc/sparc64/ > > > > > drivers/md/bcache/bset.c: In function _____btree_sort___: > > drivers/md/bcache/bset.c:1190: warning: dereferencing ___void *___ pointer > > drivers/md/bcache/bset.c:1190: error: request for member ___virtual___ in something not a structure or union > > > > Convert them to static inline functions to fix this. There are already > > plenty of users of struct page members inside , so there's no > > reason to keep them as macros. > > > > Signed-off-by: Geert Uytterhoeven > > Tested-by: David Rientjes > > I'm cringing at the page_address(mempool_alloc(..., GFP_NOIO)) in > drivers/md/bcache/bset.c, though. Yes, I was staring suspiciously at that as well. Ended up deciding that I wouldn't have coded it that way, but we should support the casting. > It's relying on that fact that > mempool_alloc() can never return NULL if __GFP_WAIT but I think this could > have all been avoided with > > struct page *page = mempool_alloc(state->pool, GFP_NOIO); > out = page_address(page); > > instead of burying the mempool_alloc() in page_address() for what I think > is cleaner code. Owell, it fixes the issue. And that would make the later virt_to_page() unnecessary. -- 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