Re: [PATCH 2/8] mm/swap: fix race on swap_info reuse betweenswapoff and swapon

[Andrew Morton]

On Mon, 27 Jan 2014 18:03:04 +0800 Weijie Yang <weijie.yang@xxxxxxxxxxx> wrote:

> swapoff clear swap_info's SWP_USED flag prematurely and free its resources
> after that. A concurrent swapon will reuse this swap_info while its previous
> resources are not cleared completely.
> 
> These late freed resources are:
>  - p->percpu_cluster
>  - swap_cgroup_ctrl[type]
>  - block_device setting
>  - inode->i_flags &= ~S_SWAPFILE
> 
> This patch clear SWP_USED flag after all its resources freed, so that swapon
> can reuse this swap_info by alloc_swap_info() safely.
> 
> This patch is just for a rare scenario, aim to correct of code.

I believe that
http://ozlabs.org/~akpm/mmots/broken-out/mm-swap-fix-race-on-swap_info-reuse-between-swapoff-and-swapon.patch
makes this patch redundant?

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