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runtime/pprof: apparent deadlock in TestGoroutineSwitch on linux-armv6l [1.16 backport] #47675

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gopherbot opened this issue Aug 12, 2021 · 3 comments
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runtime/pprof: apparent deadlock in TestGoroutineSwitch on linux-armv6l [1.16 backport] #47675

gopherbot opened this issue Aug 12, 2021 · 3 comments
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CherryPickApproved Used during the release process for point releases FrozenDueToAge
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Go1.16.8

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@gopherbot
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@mknyszek requested issue #47505 to be considered for backport to the next 1.16 minor release.

@gopherbot Please open a backport issues for 1.15 and 1.16.

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.
@gopherbot gopherbot added the CherryPickCandidate Used during the release process for point releases label Aug 12, 2021
@gopherbot gopherbot mentioned this issue Aug 12, 2021
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@gopherbot gopherbot added this to the Go1.16.8 milestone Aug 12, 2021
@gopherbot
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Change https://golang.org/cl/341853 mentions this issue: [release-branch.go1.16] runtime: drop SIGPROF while in ARM < 7 kernel helpers

@dmitshur dmitshur mentioned this issue Aug 13, 2021
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@dmitshur
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Approved as a fix for a serious issue without a workaround. This backport applies to both 1.17 (#47688) and 1.16 (this issue).

@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
gopherbot pushed a commit that referenced this issue Aug 13, 2021
@prattmic @dmitshur
[release-branch.go1.16] runtime: drop SIGPROF while in ARM < 7 kernel…
0d53084 
… 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 #47675

Change-Id: If8ba0d0fc47e45d4e6c68eca98fac4c6ed4e43c1
Reviewed-on: https://go-review.googlesource.com/c/go/+/341889
Trust: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
(cherry picked from commit 20a620f)
Reviewed-on: https://go-review.googlesource.com/c/go/+/341853
@gopherbot
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Closed by merging 0d53084 to release-branch.go1.16.

@golang golang locked and limited conversation to collaborators Aug 13, 2022
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