From 0c37626a07851668307d85c40345c0998a92e30f Mon Sep 17 00:00:00 2001 From: Jamie Liu Date: Wed, 9 Jun 2021 18:22:27 -0700 Subject: Decommit huge-page-aligned regions during reclaim under manual zeroing. PiperOrigin-RevId: 378546551 --- pkg/sentry/pgalloc/pgalloc.go | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) (limited to 'pkg') diff --git a/pkg/sentry/pgalloc/pgalloc.go b/pkg/sentry/pgalloc/pgalloc.go index b81292c46..d1a883da4 100644 --- a/pkg/sentry/pgalloc/pgalloc.go +++ b/pkg/sentry/pgalloc/pgalloc.go @@ -1062,10 +1062,20 @@ func (f *MemoryFile) runReclaim() { break } - // If ManualZeroing is in effect, pages will be zeroed on allocation - // and may not be freed by decommitFile, so calling decommitFile is - // unnecessary. - if !f.opts.ManualZeroing { + if f.opts.ManualZeroing { + // If ManualZeroing is in effect, only hugepage-aligned regions may + // be safely passed to decommitFile. Pages will be zeroed on + // reallocation, so we don't need to perform any manual zeroing + // here, whether or not decommitFile succeeds. + if startAddr, ok := hostarch.Addr(fr.Start).HugeRoundUp(); ok { + if endAddr := hostarch.Addr(fr.End).HugeRoundDown(); startAddr < endAddr { + decommitFR := memmap.FileRange{uint64(startAddr), uint64(endAddr)} + if err := f.decommitFile(decommitFR); err != nil { + log.Warningf("Reclaim failed to decommit %v: %v", decommitFR, err) + } + } + } + } else { if err := f.decommitFile(fr); err != nil { log.Warningf("Reclaim failed to decommit %v: %v", fr, err) // Zero the pages manually. This won't reduce memory usage, but at -- cgit v1.2.3