From: Rafael Aquini <aquini@redhat.com>
To: Shaohua Li <shli@kernel.org>
Cc: linux-mm@kvack.org, hughd@google.com, riel@redhat.com,
minchan@kernel.org, kmpark@infradead.org
Subject: Re: [patch 2/4 v3]swap: __swap_duplicate check bad swap entry
Date: Mon, 11 Mar 2013 22:45:56 -0300 [thread overview]
Message-ID: <20130312014555.GA4417@optiplex.redhat.com> (raw)
In-Reply-To: <20130221022219.GE32580@kernel.org>
On Thu, Feb 21, 2013 at 10:22:19AM +0800, Shaohua Li wrote:
> Sorry if you receive this one twice, last mail get mail address messed.
>
> In swapin_readahead(), read_swap_cache_async() can read a bad swap entry,
> because we don't check if readahead swap entry is bad. This doesn't break
> anything but such swapin page is wasteful and can only be freed at page
> reclaim. We avoid read such swap entry.
>
Acked-by: Rafael Aquini <aquini@redhat.com>
> And next patch will mark a swap entry bad temporarily for discard. Without this
> patch, swap entry count will be messed.
>
> Thanks Hugh to inspire swapin_readahead could use bad swap entry.
>
> Signed-off-by: Shaohua Li <shli@fusionio.com>
> ---
> mm/swapfile.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> Index: linux/mm/swapfile.c
> ===================================================================
> --- linux.orig/mm/swapfile.c 2013-02-18 15:21:09.285317914 +0800
> +++ linux/mm/swapfile.c 2013-02-18 15:21:34.545004083 +0800
> @@ -2374,6 +2374,11 @@ static int __swap_duplicate(swp_entry_t
> goto unlock_out;
>
> count = p->swap_map[offset];
> + if (unlikely(swap_count(count) == SWAP_MAP_BAD)) {
> + err = -ENOENT;
> + goto unlock_out;
> + }
> +
> has_cache = count & SWAP_HAS_CACHE;
> count &= ~SWAP_HAS_CACHE;
> err = 0;
>
> --
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next prev parent reply other threads:[~2013-03-12 1:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-21 2:22 [patch 2/4 v3]swap: __swap_duplicate check bad swap entry Shaohua Li
2013-03-12 1:45 ` Rafael Aquini [this message]
[not found] <20130221021738.GB32580@kernel.org>
2013-03-19 21:34 ` Hugh Dickins
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