On Tue, 5 Apr 2022 22:52:12 -0400 Steven Rostedt rostedt@goodmis.org wrote:
On Tue, 5 Apr 2022 19:30:25 -0700 Guenter Roeck linux@roeck-us.net wrote:
s390 tests crashed. Other failed qemu tests did not compile.
Bisect points to commit 93fe2389e6fd ("tracing: Have TRACE_DEFINE_ENUM affect trace event types as well"). Bisect log attached. Reverting the offending patch fixes the problem. Copying Steven for comments/input.
Do you have this commit?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
OK, I see what happened. I wrote that patch because a new event appeared that used enums in the field format that gets exposed to user space. This patch is only needed for events that do that. Which until this release, nothing did.
That patch was then flagged as something to backport (but it was never tagged as stable, so this was one of the "AUTOSEL" backports). And it should have only been backported if any of these new events were also backported. Otherwise, the patch is useless.
When this patch was in linux-next, it caused s390 and powerpc to crash. I found the issue and fixed it with the linked patch above, and even added a "Fixes" tag to tie the two commits together.
Both of problem patch and the fix went into mainline in the same pull request.
Here's a thought, if you decide to backport a patch to stable, and you see that there's another commit with a "Fixes" tag to the automatically selected commit. DO NOT BACKPORT IF THE FIXES PATCH FAILS TO GO BACK TOO!
This never should have been backported without the fix. Please revert that patch for any stable release that the fixes patch fails to apply.
-- Steve