Maxim Patlasov writes:
> cbt_page_alloc() drops cbt->lock before calling alloc_page(),
> then re-acquires it. It's safer to re-check that cbt->map[idx]
> is still NULL after re-acquiring the lock.
>
> Signed-off-by: Maxim Patlasov
Indeed. Ack.
> ---
> block/blk-cbt.c |7 ++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/block/blk-cbt.c b/block/blk-cbt.c
> index 8ba52fb..14ad1a2 100644
> --- a/block/blk-cbt.c
> +++ b/block/blk-cbt.c
> @@ -128,7 +128,12 @@ static int cbt_page_alloc(struct cbt_info **cbt_pp,
> unsigned long idx,
> spin_unlock_irq(&cbt->lock);
> return -ENOMEM;
> }
> - cbt->map[idx] = page;
> +
> + if (likely(CBT_PAGE(cbt, idx) == NULL))
> + cbt->map[idx] = page;
> + else
> + __free_page(page);
> +
> page = NULL;
> spin_unlock_irq(&cbt->lock);
>
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