On Tue, May 23 2023 at 3:58P -0400,
Duoming Zhou <duoming@xxxxxxxxxx> wrote:
> In order to improve the IO performance of the dm-crypt
> implementation, the commit 39d42fa96ba1 ("dm crypt:
> add flags to optionally bypass kcryptd workqueues")
> adds tasklet to do the crypto operations.
>
> The tasklet callback function kcryptd_crypt_tasklet()
> calls kcryptd_crypt() which is an original workqueue
> callback function that may sleep. As a result, the
> sleep-in-atomic-context bug may happen. The process
> is shown below.
>
> (atomic context)
> kcryptd_crypt_tasklet()
> kcryptd_crypt()
> kcryptd_crypt_write_convert()
> wait_for_completion() //may sleep
>
> The wait_for_completion() is a function that may sleep.
> In order to mitigate the bug, this patch changes
> wait_for_completion() to try_wait_for_completion().
>
> Fixes: 39d42fa96ba1 ("dm crypt: add flags to optionally bypass kcryptd workqueues")
> Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx>
> ---
> drivers/md/dm-crypt.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
> index 8b47b913ee8..5e2b2463d87 100644
> --- a/drivers/md/dm-crypt.c
> +++ b/drivers/md/dm-crypt.c
> @@ -2085,7 +2085,8 @@ static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
> crypt_finished = atomic_dec_and_test(&ctx->cc_pending);
> if (!crypt_finished && kcryptd_crypt_write_inline(cc, ctx)) {
> /* Wait for completion signaled by kcryptd_async_done() */
> - wait_for_completion(&ctx->restart);
> + while (!try_wait_for_completion(&ctx->restart))
> + ;
> crypt_finished = 1;
> }
>
> --
> 2.17.1
>
Cc'ing Ignat for closer review.
But wasn't this already addressed with this commit?:
8abec36d1274 dm crypt: do not wait for backlogged crypto request completion in softirq
Mike
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