From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id D03EC6B0033 for ; Mon, 30 Oct 2017 04:02:39 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id u78so5702047wmd.13 for ; Mon, 30 Oct 2017 01:02:39 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id k13si10632274wrf.311.2017.10.30.01.02.33 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 30 Oct 2017 01:02:33 -0700 (PDT) Date: Mon, 30 Oct 2017 09:02:30 +0100 From: Michal Hocko Subject: Re: [PATCH -mm -V2] mm, swap: Fix false error message in __swp_swapcount() Message-ID: <20171030080230.apijacsx7fd3qeox@dhcp22.suse.cz> References: <20171027055327.5428-1-ying.huang@intel.com> <20171029235713.GA4332@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171029235713.GA4332@bbox> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim 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 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? > unsigned long entry_offset = swp_offset(entry); > unsigned long offset = entry_offset; > unsigned long start_offset, end_offset; > @@ -572,6 +573,9 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask, > if (!start_offset) /* First page is swap header. */ > start_offset++; > > + if (end_offset >= si->max) > + end_offset = si->max - 1; > + > blk_start_plug(&plug); > for (offset = start_offset; offset <= end_offset ; offset++) { > /* Ok, do the async read-ahead now */ -- Michal Hocko SUSE Labs -- 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