runtime: Test Scavenge/PreserveHugePageBottom failed on linux/mips64le

[mengzhuo]

What version of Go are you using (go version)?

$ go version
go version devel +45b4ed7 Fri Nov 8 04:44:53 2019 +0000 linux/mips64le

What operating system and processor architecture are you using (go env)?

linux/mips64le

What did you do?

https://build.golang.org/log/c487a3da5c5d67c6d9619e3ed77a8a5c96d06a11
The dashboard shows it failed since https://go-review.googlesource.com/c/go/+/195697

fatal error: index out of range

goroutine 22778 [running]:
runtime.throw(0x1202b0d6c, 0x12)
	/tmp/workdir-host-linux-mipsle-mengzhuo/go/src/runtime/panic.go:1106 +0x6c fp=0xc00011fe28 sp=0xc00011fe00 pc=0x12003fd2c
runtime.panicCheck1(0x120034c50, 0x1202b0d6c, 0x12)
	/tmp/workdir-host-linux-mipsle-mengzhuo/go/src/runtime/panic.go:34 +0x110 fp=0xc00011fe50 sp=0xc00011fe28 pc=0x12003ccd0
runtime.goPanicIndexU(0x3f, 0x8)
	/tmp/workdir-host-linux-mipsle-mengzhuo/go/src/runtime/panic.go:91 +0x54 fp=0xc00011fe90 sp=0xc00011fe50 pc=0x12003ce74
runtime.(*pageBits).setRange(0xc0000ae000, 0x0, 0xff6)
	/tmp/workdir-host-linux-mipsle-mengzhuo/go/src/runtime/mpallocbits.go:38 +0x190 fp=0xc00011fea8 sp=0xc00011fe90 pc=0x120034c50
runtime.(*pallocBits).allocRange(...)
	/tmp/workdir-host-linux-mipsle-mengzhuo/go/src/runtime/mpallocbits.go:319
runtime.(*pallocData).allocRange(0xc0000ae000, 0x0, 0xff6)
	/tmp/workdir-host-linux-mipsle-mengzhuo/go/src/runtime/mpallocbits.go:369 +0x50 fp=0xc00011fec8 sp=0xc00011fea8 pc=0x120035c58
runtime.(*PallocData).AllocRange(...)
	/tmp/workdir-host-linux-mipsle-mengzhuo/go/src/runtime/export_test.go:673
runtime_test.makePallocData(0xc00049a600, 0x2, 0x2, 0x0, 0x0, 0x0, 0x88fa6230e6330)
	/tmp/workdir-host-linux-mipsle-mengzhuo/go/src/runtime/mgcscavenge_test.go:24 +0x134 fp=0xc00011ff08 sp=0xc00011fec8 pc=0x1201dbed4
runtime_test.TestPallocDataFindScavengeCandidate.func1(0xc0003c0240)
	/tmp/workdir-host-linux-mipsle-mengzhuo/go/src/runtime/mgcscavenge_test.go:251 +0x68 fp=0xc00011ff80 sp=0xc00011ff08 pc=0x120219d20
testing.tRunner(0xc0003c0240, 0xc0000740c0)
	/tmp/workdir-host-linux-mipsle-mengzhuo/go/src/testing/testing.go:954 +0xf8 fp=0xc00011ffc8 sp=0xc00011ff80 pc=0x120106f00
runtime.goexit()
	/tmp/workdir-host-linux-mipsle-mengzhuo/go/src/runtime/asm_mips64x.s:646 +0x4 fp=0xc00011ffc8 sp=0xc00011ffc8 pc=0x120080e74
created by testing.(*T).Run
	/tmp/workdir-host-linux-mipsle-mengzhuo/go/src/testing/testing.go:1005 +0x378

[mengzhuo]

Main reason: huge page is way more huge then 2M

cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size
33554432

and the test try to alloc no more than huge page limit .

PallocChunkPages - (uint(PhysHugePageSize / uintptr(PageSize) + 2)

however, when hpage is more than 2M, it will cause uint subtraction overflow.

[gopherbot]

Change https://golang.org/cl/206097 mentions this issue: runtime: skip PallocDataFindScavengeCandidate if hugepage is too large

[mknyszek]

I uploaded fix for this yesterday and filed an issue about it.

https://go-review.googlesource.com/c/go/+/205937

#35431

The only reason it hasn't landed was because I was unable to validate myself, either via the SlowBots or a gomote.

[mknyszek]

Duplicate of #35431.

[mengzhuo]

Close
Duplicate of #35431.