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runtime/pprof: apparent deadlock in TestGoroutineSwitch on linux-armv6l [1.17 backport] #47688

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prattmic opened this issue Aug 13, 2021 · 3 comments
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runtime/pprof: apparent deadlock in TestGoroutineSwitch on linux-armv6l [1.17 backport] #47688

prattmic opened this issue Aug 13, 2021 · 3 comments
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CherryPickApproved Used during the release process for point releases FrozenDueToAge
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Go1.17

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@prattmic
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#47505 should be considered for backport to the 1.17 major release.

This bug is not new and can cause deadlocks on linux/arm (GOARM=6) when profiling is turned on with no workaround. The biggest immediate issue for us is that this will cause new failures on all release builders, if not fixed.

I had to file this manually due to #25574.
@prattmic prattmic added the CherryPickCandidate Used during the release process for point releases label Aug 13, 2021
@prattmic prattmic added this to the Go1.17 milestone Aug 13, 2021
@gopherbot
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Change https://golang.org/cl/341890 mentions this issue: [release-branch.go1.17] runtime: drop SIGPROF while in ARM < 7 kernel helpers

@dmitshur
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Approved as a fix for a serious issue without a workaround. This backport applies to both 1.17 (this issue) and 1.16 (#47675).

@dmitshur dmitshur mentioned this issue Aug 13, 2021
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@dmitshur dmitshur added CherryPickApproved Used during the release process for point releases and removed CherryPickCandidate Used during the release process for point releases labels Aug 13, 2021
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Closed by merging f7b9470 to release-branch.go1.17.

gopherbot pushed a commit that referenced this issue Aug 13, 2021
@prattmic @dmitshur
[release-branch.go1.17] runtime: drop SIGPROF while in ARM < 7 kernel…
f7b9470 
… helpers

On Linux ARMv6 and below runtime/internal/atomic.Cas calls into a kernel
cas helper at a fixed address. If a SIGPROF arrives while executing the
kernel helper, the sigprof lostAtomic logic will miss that we are
potentially in the spinlock critical section, which could cause
a deadlock when using atomics later in sigprof.

For #47505
Fixes #47688

Change-Id: If8ba0d0fc47e45d4e6c68eca98fac4c6ed4e43c1
Reviewed-on: https://go-review.googlesource.com/c/go/+/341889
Trust: Michael Pratt <[email protected]>
Run-TryBot: Michael Pratt <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>
TryBot-Result: Go Bot <[email protected]>
(cherry picked from commit 20a620f)
Reviewed-on: https://go-review.googlesource.com/c/go/+/341890
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