[BUG?] b4 shazam applies unrelated patches due to dfblob collision (b4 0.14.3)

[BUG?] b4 shazam applies unrelated patches due to dfblob collision (b4 0.14.3)

[Luca Ceresoli]

Hello b4 developers,

thanks for b4, it is great!

I have a problem (bug?) to report I'm afraid.

While trying to apply a 1-patch series, b4 shazam applied the correct
patch, but:

 - in the output, it listed 22 paches being applied, and none was the
   intended one
 - at the end the branch contained 8 new patches, the first one being the
   intended one
 - it did not pick up the R-by line for the intended patch

Patch and target branch details:

 - appliying on drm-misc-next from
   ssh://git@ssh.gitlab.freedesktop.org/drm/misc/kernel.git currently at
   commit 95d628c9e473 ("drm: rcar-du: lvds: convert to
   of_drm_find_and_get_bridge()")
 - applying the 1-patch seried at
   https://lore.kernel.org/all/20251231-drm-bridge-alloc-getput-drm_of_find_bridge-kdoc-fix-v1-1-193a03f0609c@bootlin.com/

Full log follows.

----------------------8<----------------------
▶ b4 shazam  https://lore.kernel.org/all/20251231-drm-bridge-alloc-getput-drm_of_find_bridge-kdoc-fix-v1-1-193a03f0609c@bootlin.com/
Grabbing thread from lore.kernel.org/all/20251231-drm-bridge-alloc-getput-drm_of_find_bridge-kdoc-fix-v1-1-193a03f0609c@bootlin.com/t.mbox.gz
Checking for newer revisions
Grabbing search results from lore.kernel.org
  Added from v6: 22 patches
  Added from v7: 23 patches
Analyzing 48 messages in the thread
Analyzing 48 code-review messages
Will use the latest revision: v7
You can pick other revisions using the -vN flag
Checking attestation on all messages, may take a moment...
---
  ✓ [PATCH v7 1/22] drm/amd/display: Remove unnecessary SIGNAL_TYPE_HDMI_TYPE_A check
  ✓ [PATCH v7 2/22] drm: Add new general DRM property "color format"
  ✓ [PATCH v7 3/22] drm: Add enum conversions between DRM_COLOR_FORMAT and HDMI_COLORSPACE
  ✓ [PATCH v7 4/22] drm/bridge: Act on the DRM color format property
  ✓ [PATCH v7 5/22] drm/display: hdmi-state-helper: Act on color format DRM property
  ✓ [PATCH v7 6/22] drm/display: hdmi-state-helper: Try subsampling in mode_valid
  ✓ [PATCH v7 7/22] drm/i915: Implement the "color format" DRM property
  ✓ [PATCH v7 8/22] drm/amdgpu: Implement "color format" DRM property
  ✓ [PATCH v7 9/22] drm/rockchip: Add YUV422 output mode constants for VOP2
  ✓ [PATCH v7 10/22] drm/rockchip: vop2: Fix YUV444 output
  ✓ [PATCH v7 11/22] drm/rockchip: vop2: Add RK3576 to the RG swap special case
  ✓ [PATCH v7 12/22] drm/rockchip: vop2: Recognise 10/12-bit YUV422 as YUV formats
  ✓ [PATCH v7 13/22] drm/rockchip: vop2: Set correct output format for RK3576 YUV422
  ✓ [PATCH v7 14/22] drm/bridge: dw-hdmi-qp: Implement atomic_get_output_bus_fmts
  ✓ [PATCH v7 15/22] drm/rockchip: dw_hdmi_qp: Implement "color format" DRM property
  ✓ [PATCH v7 16/22] drm/rockchip: dw_hdmi_qp: Set supported_formats platdata
  ✓ [PATCH v7 17/22] drm/connector: Register color format property on HDMI connectors
    + Reviewed-by: Maxime Ripard <mripard@kernel.org> (✓ DKIM/kernel.org)
  ✓ [PATCH v7 18/22] drm/tests: hdmi: Add tests for the color_format property
  ✓ [PATCH v7 19/22] drm/tests: hdmi: Add tests for HDMI helper's mode_valid
  ✓ [PATCH v7 20/22] drm/tests: edid: Add __maybe_unused attribute to EDID definitions
  ✓ [PATCH v7 21/22] drm/tests: bridge: Add KUnit tests for bridge chain format selection
  ✓ [PATCH v7 22/22] drm/bridge: Document bridge chain format selection
  ---
  ✓ Signed: DKIM/collabora.com
---
Total patches: 22
---
 Base: using specified base-commit dc0b90be8d513256a6594095731a702287f29602
 Deps: looking for dependencies matching 1 patch-ids
Grabbing search results from lore.kernel.org
 Deps: Applying prerequisite patch: [PATCH] drm/bridge: fix kdoc syntax
Applying: drm/bridge: fix kdoc syntax
Applying: drm/amd/display: Remove unnecessary SIGNAL_TYPE_HDMI_TYPE_A check
Applying: drm: Add new general DRM property "color format"
Applying: drm: Add enum conversions between DRM_COLOR_FORMAT and HDMI_COLORSPACE
Applying: drm/bridge: Act on the DRM color format property
Applying: drm/display: hdmi-state-helper: Act on color format DRM property
Applying: drm/display: hdmi-state-helper: Try subsampling in mode_valid
Applying: drm/i915: Implement the "color format" DRM property
Applying: drm/amdgpu: Implement "color format" DRM property
Patch failed at 0009 drm/amdgpu: Implement "color format" DRM property
error: sha1 information is lacking or useless (drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c).
error: could not build fake ancestor
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"
▶ git log --oneline  drm-misc/drm-misc-next..
38ebb10f2b83 (HEAD -> drm-misc-next) drm/i915: Implement the "color format" DRM property
01a8c2dc91e0 drm/display: hdmi-state-helper: Try subsampling in mode_valid
50fdbeeed537 drm/display: hdmi-state-helper: Act on color format DRM property
9cb7ad4f0a10 drm/bridge: Act on the DRM color format property
280fd2cb4aa5 drm: Add enum conversions between DRM_COLOR_FORMAT and HDMI_COLORSPACE
7f731f50bf3d drm: Add new general DRM property "color format"
6e173053fa5c drm/amd/display: Remove unnecessary SIGNAL_TYPE_HDMI_TYPE_A check
7a4637bce4f6 drm/bridge: fix kdoc syntax
▶
----------------------8<----------------------

Clue: my colleague Louis found that both the intended patch and some in the
other thread that got applied match the 'dfblob:6dcf8f6d3ec' query on
lore. Maybe the query needs to become more restrictive?

Workaround: I managed to apply the patch 100% correctly by adding the '-v1'
flag to b4. Luckily the other patches matching 'dfblob:6dcf8f6d3ec' are at
different versions. This workaround would not work otherwise, so it is not
really generic.

Best regards,
Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [BUG?] b4 shazam applies unrelated patches due to dfblob collision (b4 0.14.3)

[Konstantin Ryabitsev]

On Wed, Jan 21, 2026 at 05:47:19PM +0100, Luca Ceresoli wrote:
> I have a problem (bug?) to report I'm afraid.
> 
> While trying to apply a 1-patch series, b4 shazam applied the correct
> patch, but:
> 
>  - in the output, it listed 22 paches being applied, and none was the
>    intended one
>  - at the end the branch contained 8 new patches, the first one being the
>    intended one
>  - it did not pick up the R-by line for the intended patch

Thanks for the report, adding it to tracking.

bugspray tag b4/shazam

-K

Re: b4 shazam applies unrelated patches due to dfblob collision (b4 0.14.3)

[B4 Bugbot]

Hello:

This conversation is now tracked by b4 bug tracker.
There is no need to do anything else, just keep talking.

--
Deet-doot-dot, I am a bot.
b4 bug tracker (bugspray 0.1-dev)

Re: b4 shazam applies unrelated patches due to dfblob collision (b4 0.14.3)

[B4 Bugbot]

Konstantin Ryabitsev writes in commit 8a652aeaaa90be4c26d7c2fb5cf899840c737ebd:

Fix get_extra_series pulling in unrelated prerequisite series

When searching for newer revisions by change-id, the nq: query on
lore can match messages that reference our change-id in a
prerequisite-change-id trailer rather than as their own change-id.
This causes get_extra_series to pull in entirely unrelated series,
which b4 then treats as the "latest revision" and tries to apply.

After collecting candidate messages from the search, validate that
each revision actually belongs to the same series by checking that
at least one message per revision contains a standalone change-id
line matching ours. Revisions that only reference the change-id as
a prerequisite are rejected.

This affects b4 shazam, b4 review, and b4 diff, which all use
get_extra_series for revision discovery.

Reported-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Closes: https://lore.kernel.org/tools/DFUF52RW81LD.28YE20HG4P0L1@bootlin.com/ # b9c4cde
Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
Assisted-by: claude-opus-4-6

--
Deet-doot-dot, I am a bot.
b4 bug tracker (bugspray 0.1-dev)