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doc: Update s390 kernel prerequisite
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Signed-off-by: Sumanth Korikkar <[email protected]>
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sumanthkorikkar authored and Sumanth Korikkar committed Feb 23, 2023
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Expand Up @@ -16,6 +16,7 @@
- eed38cd2f46f s390/nospec: generate single register thunks if possible
- 2268169c14e5 s390: remove unused expoline to BC instructions
- f0003a9e4c18 s390/entry: remove unused expoline thunk
- ded466e18066 s390/unwind: fix fgraph return address recovery

**v5.16:**
- torvalds/linux@f6ac18f sched: Improve try_invoke_on_locked_down_task()
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3 comments on commit 324a437

@john-cabaj
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It looks like d81675b60d09 "s390/unwind: recover kretprobe modified return address in stacktrace" is also required for a clean cherry-pick of ded466e18066 "s390/unwind: fix fgraph return address recovery".

At any rate, I've had success with using kpatch with all commits above prior to including any s390/unwind patches (with UBSAN disabled, as discussed in #1328). Is this preventing particular kpatch functionality?

@joe-lawrence
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Hi @john-cabaj : missing d81675b60d09 ("s390/unwind: recover kretprobe modified return address in stacktrace") can cause livepatch transition problems when ftrace graph tracing is in effect. See SUSE/qa_test_klp#17 for a test case. AFAIK there is nothing kpatch specific about that commit, but it is similarly affected since it's leveraging kernel livepatch.

@sumanthkorikkar
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@john-cabaj ,agree to what Joe mentioned, Would be essential for live patch transitions. Thanks

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