Re: FAILED: patch "[PATCH] padata: Remove broken queue flushing" failed to apply to 4.19-stable tree

[Sasha Levin <sashal@kernel.org>]

On Fri, Feb 07, 2020 at 09:46:31AM +0100, gregkh@linuxfoundation.org wrote:
>
>The patch below does not apply to the 4.19-stable tree.
>If someone wants it applied there, or to any other stable or longterm
>tree, then please email the backport, including the original git commit
>id to <stable@vger.kernel.org>.
>
>thanks,
>
>greg k-h
>
>------------------ original commit in Linus's tree ------------------
>
>From 07928d9bfc81640bab36f5190e8725894d93b659 Mon Sep 17 00:00:00 2001
>From: Herbert Xu <herbert@gondor.apana.org.au>
>Date: Tue, 19 Nov 2019 13:17:31 +0800
>Subject: [PATCH] padata: Remove broken queue flushing
>
>The function padata_flush_queues is fundamentally broken because
>it cannot force padata users to complete the request that is
>underway.  IOW padata has to passively wait for the completion
>of any outstanding work.
>
>As it stands flushing is used in two places.  Its use in padata_stop
>is simply unnecessary because nothing depends on the queues to
>be flushed afterwards.
>
>The other use in padata_replace is more substantial as we depend
>on it to free the old pd structure.  This patch instead uses the
>pd->refcnt to dynamically free the pd structure once all requests
>are complete.
>
>Fixes: 2b73b07ab8a4 ("padata: Flush the padata queues actively")
>Cc: <stable@vger.kernel.org>
>Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
>Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
>Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Conflicts are due to not having 6fc4dbcf0276 ("padata: Replace delayed
timer with immediate workqueue in padata_reorder") in older kernels.
I've fixed it up and queued for 4.19-4.4.

-- 
Thanks,
Sasha