runtime: async preemption breaks darwin/arm #35439
Comments
Enabling async preemption on darwin/arm and darwin/arm64 causes the builder to fail, e.g. https://build.golang.org/log/03f727b8f91b0c75bf54ff508d7d2f00b5cad4bf Due to the limited resource, I haven't been able to get access on those devices to debug. Disable async preemption for now. Updates #35439. Change-Id: I5a31ad6962c2bae8e6e9b8303c494610a8a4e50a Reviewed-on: https://go-review.googlesource.com/c/go/+/205842 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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Change https://golang.org/cl/205842 mentions this issue: |
bradfitz
added
help wanted
mobile
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/cc @eliasnaur @steeve |
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Unfortunately, the Corellium builders have networks problem at the moment. If you have any debugging CLs you'd like me to test, please let me know. I can run the ios tests locally. |
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The corellium builders are up again, so when they're through the backlog you should be able to gomote in. I've started another iOS device to speed things up. |
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Thanks @eliasnaur ! I was able to access the Corellium gomote and dig into what's going on. I'll send CLs shortly. It should work on darwin/arm64 now. The problem for ARM64 doesn't seem to appear on ARM32. I couldn't access the ARM32 builder. So I still don't know if it works on ARM32. |
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Change https://golang.org/cl/206418 mentions this issue: |
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Change https://golang.org/cl/206419 mentions this issue: |
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Very nice, thank you! Let's just submit this and see what happens. Corellium does not support arm32, so gomoting is diffcult. |
iOS does not support SA_ONSTACK. The signal handler runs on the G stack. Any writes below the SP may be clobbered by the signal handler (even without call injection). So we save LR after decrementing SP on iOS. Updates #35439. Change-Id: Ia6d7a0669e0bcf417b44c031d2e26675c1184165 Reviewed-on: https://go-review.googlesource.com/c/go/+/206418 Run-TryBot: Cherry Zhang <cherryyz@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
The problem should be fixed by the previous CL. Reenable async preemption on darwin/arm64. Updates #35439. Change-Id: I93e8c4702b4d8fe6abaa6fc9c27def5c8aed1b59 Reviewed-on: https://go-review.googlesource.com/c/go/+/206419 Reviewed-by: Keith Randall <khr@golang.org>
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Change https://golang.org/cl/206957 mentions this issue: |
cherrymui
changed the title
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Async preemption also causes linux/arm32 to segfault on current tip. Segfaults disappear after async preemption is disabled (GODEBUG=asyncpreemptoff=1). |
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@reusee Can you provide more details? The linux-arm builder seems to be working. Thanks. |
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@ianlancetaylor It's a proxy program for internal use. I'm trying to find a reproduce program. Sometimes it crash with 'fatal: bad g in signal handler', most times just 'Segmentation fault'. |
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I found a workaround for the segfault that is settings GOMAXPROCS to 1. Still can't find a short reproduce. It's several thousand lines of tightly coupled codes. |
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Change https://golang.org/cl/227198 mentions this issue: |
What version of Go are you using (
go version)?tip (a930fed)
Does this issue reproduce with the latest release?
No
What operating system and processor architecture are you using (
go env)?darwin/arm and darwin/arm64
What did you do?
After async preemption is enabled, the darwin/arm64 builder starts to fail, e.g.
https://build.golang.org/log/03f727b8f91b0c75bf54ff508d7d2f00b5cad4bf
I haven't been able to get access to the builders due to the limited resource. I'll look into the failure once I get the access.
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