Frederic Barrat [off-list ref] writes:

On 27/05/2021 04:13, Alexey Kardashevskiy wrote:

quoted

On 27/05/2021 00:45, Frederic Barrat wrote:

quoted

This reverts commit 3c0468d4451eb6b4f6604370639f163f9637a479.

That commit was breaking alignment guarantees for the DMA address when
allocating coherent mappings, as described in
Documentation/core-api/dma-api-howto.rst

It was also noticed by Mellanox' driver:
[ 1515.763621] mlx5_core c002:01:00.0: 
mlx5_frag_buf_alloc_node:146:(pid 13402): unexpected map alignment: 
0x0800000000c61000, page_shift=16
[ 1515.763635] mlx5_core c002:01:00.0: mlx5_cqwq_create:181:(pid
13402): mlx5_frag_buf_alloc_node() failed, -12

Signed-off-by: Frederic Barrat <redacted>

Should it be

Fixes: 3c0468d4451e ("powerpc/kernel/iommu: Align size for 
IOMMU_PAGE_SIZE() to save TCEs")

?

I had been wondering the same... I can see many revert commits with and 
without a "Fixes:" line. Since here the offending commit was merged in 
the latest merge window, I was thinking Fixes doesn't really bring 
anything, it will all stay internal to v5.13 development.

It is still valuable, even if the fix lands in the same release as the
original commit.

The original commit could have been backported elsewhere, so the Fixes
tag is still useful in that case.

I'd be happy to hear of the expected way of handling it. I'm guessing
a big part of the answer is whether the tooling looking for a "Fixes"
line is also looking for reverts.

Tooling should look for both Fixes and reverts, because not everyone is
going to remember to add Fixes tags to a revert.

But I think it's still helpful to include the Fixes tag, I sometimes
grep the commit log for "Fixes: <sha>" and I'm sure others do too.

I've added it to this commit, no need to resend.

cheers