From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id 675B26B0069 for ; Tue, 31 Oct 2017 03:37:13 -0400 (EDT) Received: by mail-pg0-f69.google.com with SMTP id g6so16050791pgn.11 for ; Tue, 31 Oct 2017 00:37:13 -0700 (PDT) Received: from lgeamrelo11.lge.com (LGEAMRELO11.lge.com. [156.147.23.51]) by mx.google.com with ESMTP id t4si1009136plo.470.2017.10.31.00.37.11 for ; Tue, 31 Oct 2017 00:37:12 -0700 (PDT) Date: Tue, 31 Oct 2017 16:37:10 +0900 From: Minchan Kim Subject: Re: [PATCH -mm -V2] mm, swap: Fix false error message in __swp_swapcount() Message-ID: <20171031073710.GA857@bbox> References: <20171027055327.5428-1-ying.huang@intel.com> <20171029235713.GA4332@bbox> <20171030080230.apijacsx7fd3qeox@dhcp22.suse.cz> <20171031021702.GA942@bbox> <20171031073107.x5rpkf4emf74ymyk@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171031073107.x5rpkf4emf74ymyk@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: "Huang, Ying" , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huang Ying , Tim Chen , stable@vger.kernel.org, Christian Kujau On Tue, Oct 31, 2017 at 08:31:07AM +0100, Michal Hocko wrote: > On Tue 31-10-17 11:17:02, Minchan Kim wrote: > > On Mon, Oct 30, 2017 at 09:02:30AM +0100, Michal Hocko wrote: > > > On Mon 30-10-17 08:57:13, Minchan Kim wrote: > > > [...] > > > > Although it's better than old, we can make it simple, still. > > > > > > > > diff --git a/include/linux/swapops.h b/include/linux/swapops.h > > > > index 291c4b534658..f50d5a48f03a 100644 > > > > --- a/include/linux/swapops.h > > > > +++ b/include/linux/swapops.h > > > > @@ -41,6 +41,13 @@ static inline unsigned swp_type(swp_entry_t entry) > > > > return (entry.val >> SWP_TYPE_SHIFT(entry)); > > > > } > > > > > > > > +extern struct swap_info_struct *swap_info[]; > > > > + > > > > +static inline struct swap_info_struct *swp_si(swp_entry_t entry) > > > > +{ > > > > + return swap_info[swp_type(entry)]; > > > > +} > > > > + > > > > /* > > > > * Extract the `offset' field from a swp_entry_t. The swp_entry_t is in > > > > * arch-independent format > > > > diff --git a/mm/swap_state.c b/mm/swap_state.c > > > > index 378262d3a197..a0fe2d54ad09 100644 > > > > --- a/mm/swap_state.c > > > > +++ b/mm/swap_state.c > > > > @@ -554,6 +554,7 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask, > > > > struct vm_area_struct *vma, unsigned long addr) > > > > { > > > > struct page *page; > > > > + struct swap_info_struct *si = swp_si(entry); > > > > > > Aren't you accessing beyond the array here? > > > > I couldn't understand what you intend. Could you explain what case does it accesses > > beyond the arrary? > > what if swp_type > nr_swapfiles Logicall, it shouldn't be happen but it's a bug once it happens. Such a bug can happen everywhere. Why do you want to take care in this logic? -- 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