On 4/8/24 5:00 PM, Vlastimil Babka wrote:
On 4/8/24 2:57 PM, Greg Kroah-Hartman wrote:
6.8-stable review patch. If anyone has any objections, please let me know.
From: Peter Collingbourne pcc@google.com
[ Upstream commit a6c1d9cb9a68bfa4512248419c4f4d880d19fe90 ]
Commit 3ee34eabac2a ("lib/stackdepot: fix first entry having a 0-handle") changed the meaning of the pool_index field to mean "the pool index plus 1". This made the code accessing this field less self-documenting, as well as causing debuggers such as drgn to not be able to easily remain compatible with both old and new kernels, because they typically do that by testing for presence of the new field. Because stackdepot is a debugging tool, we should make sure that it is debugger friendly. Therefore, give the field a different name to improve readability as well as enabling debugger backwards compatibility.
This is needed in 6.9, which would otherwise become an odd release with the new semantics and old name so debuggers wouldn't recognize the new semantics there.
This got me curious so I did check what's going on, so mentioning the result here others don't need to repeat that.
Fixes: 3ee34eabac2a ("lib/stackdepot: fix first entry having a 0-handle")
It's because this was backported to 6.8.2 despite:
This bug has been lurking since the very beginning of stackdepot, but no one really cared as it seems. Because of that I am not adding a Fixes tag.
Nevermind, it was backported as
Stable-dep-of: dc24559472a6 ("lib/stackdepot: off by one in depot_fetch_stack()")
https://lore.kernel.org/all/20240324223455.1342824-513-sashal@kernel.org/