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SubjectRe: [PATCH v3 02/10] zram: use zram->lock to protect zram_free_page() in swap free notify path
On 06/06/2013 06:07 PM, Jiang Liu wrote:
> zram_slot_free_notify() is free-running without any protection from
> concurrent operations. So there are race conditions between
> zram_bvec_read()/zram_bvec_write() and zram_slot_free_notify(),
> and possible consequences include:
> 1) Trigger BUG_ON(!handle) on zram_bvec_write() side.
> 2) Access to freed pages on zram_bvec_read() side.
> 3) Break some fields (bad_compress, good_compress, pages_stored)
> in zram->stats if the swap layer makes concurrently call to
> zram_slot_free_notify().
>
> So enhance zram_slot_free_notify() to acquire writer lock on zram->lock
> before calling zram_free_page().
>
> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
> Cc: stable@vger.kernel.org

Acked-by: Jerome Marchand <jmarchand@redhat.com>




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