Re: [PATCH] padata: upgrade smp_mb__after_atomic to smp_mb in padata_do_serial

[Herbert Xu]

On Mon, Jun 08, 2020 at 05:26:52PM -0400, Daniel Jordan wrote:
> A 5.7 kernel hangs during a tcrypt test of padata that waits for an AEAD
> request to finish.  This is only seen on large machines running many
> concurrent requests.
> 
> The issue is that padata never serializes the request.  The removal of
> the reorder_objects atomic missed that the memory barrier in
> padata_do_serial() depends on it.
> 
> Upgrade the barrier from smp_mb__after_atomic to smp_mb to get correct
> ordering again.
> 
> Fixes: 3facced7aeed1 ("padata: remove reorder_objects")
> Signed-off-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Cc: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
> Cc: linux-crypto@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
>  kernel/padata.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
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