blob: 793d4e277ca062104ec31fd63e50ace05bab65b3 [file] [log] [blame]
// Copyright 2022 The Fuchsia Authors
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
#include "vm/anonymous_page_requester.h"
#include <lib/lazy_init/lazy_init.h>
#include <vm/pmm.h>
namespace {
lazy_init::LazyInit<AnonymousPageRequester> anonymous_page_requester;
// Need to hold one refcount permanently so that other RefPtrs to the requester can be created and
// deleted.
lazy_init::LazyInit<fbl::RefPtr<AnonymousPageRequester>> anonymous_page_requester_ref;
} // namespace
zx_status_t AnonymousPageRequester::FillRequest(PageRequest* request) {
if (request->offset_ == UINT64_MAX) {
// Pretend a read request at offset 0. The only actor that should ever inspect these values is
// us, and we don't, so they can be anything.
request->Init(fbl::RefPtr<PageRequestInterface>(this), 0, page_request_type::READ,
VmoDebugInfo{0, 0});
} else {
DEBUG_ASSERT(request->batch_state_ == PageRequest::BatchState::Accepting);
// We ignore batch requests for this requester, so should only be here if this was a batch
// request started against a different interface.
ASSERT(request->src_.get() != static_cast<PageRequestInterface*>(this));
return request->FinalizeRequest();
// If this is a batch request complete it immediately. There is no value in finding additional
// pages, since the only thing we are going to do is wait on the pmm.
if (request->batch_state_ == PageRequest::BatchState::Accepting) {
request->batch_state_ = PageRequest::BatchState::Finalized;
zx_status_t AnonymousPageRequester::WaitOnRequest(PageRequest* request) {
// Although the pmm_wait_till_free_pages call will unblock based on bounded kernel action, and not
// some unbounded user request, the kernel might need to acquire arbitrary locks to achieve this.
// Therefore blanket require no locks here to ensure no accidental lock dependencies. This can be
// relaxed in the future if necessary.
// This should only ever end up waiting momentarily until reclamation catches up. As such if we
// end up waiting for a long time then this is probably a sign of a bug in reclamation somewhere,
// so we want to make some noise here.
constexpr zx_duration_t kReportWaitTime = ZX_SEC(5);
zx_status_t status = ZX_OK;
uint32_t waited = 0;
while ((status = pmm_wait_till_should_retry_single_alloc(Deadline::after(kReportWaitTime))) ==
printf("WARNING: Waited %" PRIi64 " seconds to retry PMM allocations\n",
(kReportWaitTime * waited) / ZX_SEC(1));
// Whether we succeeded or failed, this request is finished so clear out offset_.
request->offset_ = UINT64_MAX;
return status;
// static
AnonymousPageRequester& AnonymousPageRequester::Get() { return anonymous_page_requester.Get(); }
// static
void AnonymousPageRequester::Init() {