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runtime: fix GODEBUG=gccheckmark=1 and add smoke test

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This change fixes GODEBUG=gccheckmark=1 which seems to have bit-rotted.
Because the root jobs weren't being reset, it wasn't doing anything.
Then, it turned out that checkmark mode would queue up noscan objects in
workbufs, which caused it to fail. Then it turned out checkmark mode was
broken with user arenas, since their heap arenas are not registered
anywhere. Then, it turned out that checkmark mode could just not run
properly if the goroutine's preemption flag was set (since
sched.gcwaiting is true during the STW). And lastly, it turned out that
async preemption could cause erroneous checkmark failures.

This change fixes all these issues and adds a simple smoke test to dist
to run the runtime tests under gccheckmark, which exercises all of these
issues.

Fixes #69074.
Fixes #69377.
Fixes #69376.

Change-Id: Iaa0bb7b9e63ed4ba34d222b47510d6292ce168bc
Cq-Include-Trybots: luci.golang.try:gotip-linux-amd64-longtest
Reviewed-on: https://go-review.googlesource.com/c/go/+/608915
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
This commit is contained in:
Michael Anthony Knyszek 2024-08-27 21:02:02 +00:00 • committed by Gopher Robot
parent 4f11d5879a
commit b25b5f3ff4
8 changed files with 100 additions and 48 deletions
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27
src/runtime/mheap.go
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@ -108,9 +108,9 @@ type mheap struct {
// Page reclaimer state
// reclaimIndex is the page index in allArenas of next page to
// reclaimIndex is the page index in heapArenas of next page to
// reclaim. Specifically, it refers to page (i %
// pagesPerArena) of arena allArenas[i / pagesPerArena].
// pagesPerArena) of arena heapArenas[i / pagesPerArena].
//
// If this is >= 1<<63, the page reclaimer is done scanning
// the page marks.
@ -165,22 +165,31 @@ type mheap struct {
// (the actual arenas). This is only used on 32-bit.
arena linearAlloc
// allArenas is the arenaIndex of every mapped arena. This can
// be used to iterate through the address space.
// heapArenas is the arenaIndex of every mapped arena mapped for the heap.
// This can be used to iterate through the heap address space.
//
// Access is protected by mheap_.lock. However, since this is
// append-only and old backing arrays are never freed, it is
// safe to acquire mheap_.lock, copy the slice header, and
// then release mheap_.lock.
allArenas []arenaIdx
heapArenas []arenaIdx
// sweepArenas is a snapshot of allArenas taken at the
// userArenaArenas is the arenaIndex of every mapped arena mapped for
// user arenas.
//
// Access is protected by mheap_.lock. However, since this is
// append-only and old backing arrays are never freed, it is
// safe to acquire mheap_.lock, copy the slice header, and
// then release mheap_.lock.
userArenaArenas []arenaIdx
// sweepArenas is a snapshot of heapArenas taken at the
// beginning of the sweep cycle. This can be read safely by
// simply blocking GC (by disabling preemption).
sweepArenas []arenaIdx
// markArenas is a snapshot of allArenas taken at the beginning
// of the mark cycle. Because allArenas is append-only, neither
// markArenas is a snapshot of heapArenas taken at the beginning
// of the mark cycle. Because heapArenas is append-only, neither
// this slice nor its contents will change during the mark, so
// it can be read safely.
markArenas []arenaIdx
@ -1494,7 +1503,7 @@ func (h *mheap) grow(npage uintptr) (uintptr, bool) {
// Not enough room in the current arena. Allocate more
// arena space. This may not be contiguous with the
// current arena, so we have to request the full ask.
av, asize := h.sysAlloc(ask, &h.arenaHints, true)
av, asize := h.sysAlloc(ask, &h.arenaHints, &h.heapArenas)
if av == nil {
inUse := gcController.heapFree.load() + gcController.heapReleased.load() + gcController.heapInUse.load()
print("runtime: out of memory: cannot allocate ", ask, "-byte block (", inUse, " in use)\n")