From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f174.google.com (mail-pd0-f174.google.com [209.85.192.174]) by kanga.kvack.org (Postfix) with ESMTP id 88E336B0037 for ; Wed, 24 Sep 2014 03:57:13 -0400 (EDT) Received: by mail-pd0-f174.google.com with SMTP id g10so7607582pdj.33 for ; Wed, 24 Sep 2014 00:57:13 -0700 (PDT) Received: from lgeamrelo01.lge.com (lgeamrelo01.lge.com. [156.147.1.125]) by mx.google.com with ESMTP id km9si24901549pdb.208.2014.09.24.00.57.11 for ; Wed, 24 Sep 2014 00:57:12 -0700 (PDT) Date: Wed, 24 Sep 2014 16:57:42 +0900 From: Minchan Kim Subject: Re: [PATCH v1 2/5] mm: add full variable in swap_info_struct Message-ID: <20140924075742.GB3181@bbox> References: <1411344191-2842-1-git-send-email-minchan@kernel.org> <1411344191-2842-3-git-send-email-minchan@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Dan Streetman Cc: Andrew Morton , linux-kernel , Linux-MM , Hugh Dickins , Shaohua Li , Jerome Marchand , Sergey Senozhatsky , Nitin Gupta , Luigi Semenzato , juno.choi@lge.com On Tue, Sep 23, 2014 at 10:53:05PM -0400, Dan Streetman wrote: > On Sun, Sep 21, 2014 at 8:03 PM, Minchan Kim wrote: > > Now, swap leans on !p->highest_bit to indicate a swap is full. > > It works well for normal swap because every slot on swap device > > is used up when the swap is full but in case of zram, swap sees > > still many empty slot although backed device(ie, zram) is full > > since zram's limit is over so that it could make trouble when > > swap use highest_bit to select new slot via free_cluster. > > > > This patch introduces full varaiable in swap_info_struct > > to solve the problem. > > > > Suggested-by: Dan Streetman > > Signed-off-by: Minchan Kim > > --- > > include/linux/swap.h | 1 + > > mm/swapfile.c | 33 +++++++++++++++++++-------------- > > 2 files changed, 20 insertions(+), 14 deletions(-) > > > > diff --git a/include/linux/swap.h b/include/linux/swap.h > > index ea4f926e6b9b..a3c11c051495 100644 > > --- a/include/linux/swap.h > > +++ b/include/linux/swap.h > > @@ -224,6 +224,7 @@ struct swap_info_struct { > > struct swap_cluster_info free_cluster_tail; /* free cluster list tail */ > > unsigned int lowest_bit; /* index of first free in swap_map */ > > unsigned int highest_bit; /* index of last free in swap_map */ > > + bool full; /* whether swap is full or not */ > > unsigned int pages; /* total of usable pages of swap */ > > unsigned int inuse_pages; /* number of those currently in use */ > > unsigned int cluster_next; /* likely index for next allocation */ > > diff --git a/mm/swapfile.c b/mm/swapfile.c > > index c07f7f4912e9..209112cf8b83 100644 > > --- a/mm/swapfile.c > > +++ b/mm/swapfile.c > > @@ -558,7 +558,7 @@ checks: > > } > > if (!(si->flags & SWP_WRITEOK)) > > goto no_page; > > - if (!si->highest_bit) > > + if (si->full) > > goto no_page; > > if (offset > si->highest_bit) > > scan_base = offset = si->lowest_bit; > > @@ -589,6 +589,7 @@ checks: > > spin_lock(&swap_avail_lock); > > plist_del(&si->avail_list, &swap_avail_head); > > spin_unlock(&swap_avail_lock); > > + si->full = true; > > } > > si->swap_map[offset] = usage; > > inc_cluster_info_page(si, si->cluster_info, offset); > > @@ -653,14 +654,14 @@ start_over: > > plist_requeue(&si->avail_list, &swap_avail_head); > > spin_unlock(&swap_avail_lock); > > spin_lock(&si->lock); > > - if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) { > > + if (si->full || !(si->flags & SWP_WRITEOK)) { > > spin_lock(&swap_avail_lock); > > if (plist_node_empty(&si->avail_list)) { > > spin_unlock(&si->lock); > > goto nextsi; > > } > > - WARN(!si->highest_bit, > > - "swap_info %d in list but !highest_bit\n", > > + WARN(si->full, > > + "swap_info %d in list but swap is full\n", > > si->type); > > WARN(!(si->flags & SWP_WRITEOK), > > "swap_info %d in list but !SWP_WRITEOK\n", > > @@ -796,21 +797,25 @@ static unsigned char swap_entry_free(struct swap_info_struct *p, > > > > /* free if no reference */ > > if (!usage) { > > + bool was_full; > > + > > dec_cluster_info_page(p, p->cluster_info, offset); > > if (offset < p->lowest_bit) > > p->lowest_bit = offset; > > - if (offset > p->highest_bit) { > > - bool was_full = !p->highest_bit; > > + if (offset > p->highest_bit) > > p->highest_bit = offset; > > - if (was_full && (p->flags & SWP_WRITEOK)) { > > - spin_lock(&swap_avail_lock); > > - WARN_ON(!plist_node_empty(&p->avail_list)); > > - if (plist_node_empty(&p->avail_list)) > > - plist_add(&p->avail_list, > > - &swap_avail_head); > > - spin_unlock(&swap_avail_lock); > > - } > > + was_full = p->full; > > + > > + if (was_full && (p->flags & SWP_WRITEOK)) { > > was_full was only needed because highest_bit was reset to offset right > before checking for fullness, so now that ->full is used instead of > !highest_bit, was_full isn't needed anymore, you can just check > p->full. Okay. -- Kind regards, Minchan 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