[PATCH v2] docs: bug-bisect: add a note about bisecting -next

[Thorsten Leemhuis]

Explicitly mention how to bisect -next, as nothing in the kernel tree
currently explains that bisects between -next versions won't work well
and it's better to bisect between mainline and -next.

Co-developed-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Reviewed-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Thorsten Leemhuis <linux@xxxxxxxxxxxxx>
---
v2:
- slightly change patch descption
- make the text more how-toish to better match the rest of the document

v1: https://lore.kernel.org/all/20241022-doc-bisect-next-v1-1-196c0a60d554@xxxxxxxxxx/
- initial release
---
 Documentation/admin-guide/bug-bisect.rst | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Documentation/admin-guide/bug-bisect.rst b/Documentation/admin-guide/bug-bisect.rst
index 585630d14581c7..47264c199247e6 100644
--- a/Documentation/admin-guide/bug-bisect.rst
+++ b/Documentation/admin-guide/bug-bisect.rst
@@ -108,6 +108,27 @@ a fully reliable and straight-forward way to reproduce the regression, too.*
 With that the process is complete. Now report the regression as described by
 Documentation/admin-guide/reporting-issues.rst.
 
+Bisecting linux-next
+--------------------
+
+If you face a problem only happening in linux-next, bisect between the
+linux-next branches 'stable' and 'master'. The following commands will start
+the process for a linux-next tree you added as a remote called 'next'::
+
+  git bisect start
+  git bisect good next/stable
+  git bisect bad next/master
+
+The 'stable' branch refers to the state of linux-mainline the current
+linux-next release (found in the 'master' branch) is based on -- the former
+thus should be free of any problems that show up in -next, but not in Linus'
+tree.
+
+This will bisect across a wide range of changes, some of which you might have
+used in earlier linux-next releases without problems. Sadly there is no simple
+way to avoid checking them: bisecting from one linux-next release to a later
+one (say between 'next-20241020' and 'next-20241021') is impossible, as they
+share no common history.
 
 Additional reading material
 ---------------------------

base-commit: 062d98be0e3f6dcf08e40a1101e967b2eb4fb92f
-- 
2.45.0