Attachment 341194 Details for Bug 184261 – Patch

[patch] Patch

bug-184261-20180524181034.patch (text/plain), 41.98 KB, created by Carlos Alberto Lopez Perez on 2018-05-24 09:10:37 PDT

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Creator: Carlos Alberto Lopez Perez

Created: 2018-05-24 09:10:37 PDT

Size: 41.98 KB

patch

obsolete

>Subversion Revision: 232151
>diff --git a/Source/WTF/ChangeLog b/Source/WTF/ChangeLog
>index 7bae582c6b028421e0c674dd929ba70cafb7230a..6ab1a3f70a9dcd9d07d9d46af823bbe2d69ded5b 100644
>--- a/Source/WTF/ChangeLog
>+++ b/Source/WTF/ChangeLog
>@@ -1,3 +1,18 @@
>+2018-05-24  Carlos Alberto Lopez Perez  <clopez@igalia.com>
>+
>+        [GTK][WPE] Memory pressure monitor doesn't reliable notify all the subprocesses
>+        https://bugs.webkit.org/show_bug.cgi?id=184261
>+
>+        Reviewed by Carlos Garcia Campos.
>+
>+        Receive the memory pressure notifications from the UIProcess memory monitor via WebKit IPC.
>+
>+        * wtf/MemoryPressureHandler.h:
>+        * wtf/linux/MemoryPressureHandlerLinux.cpp:
>+        (WTF::MemoryPressureHandler::triggerMemoryPressureEvent):
>+        (WTF::MemoryPressureHandler::install):
>+        (WTF::MemoryPressureHandler::uninstall):
>+
> 2018-05-23  Eric Carlson  <eric.carlson@apple.com>
> 
>         Avoid loading AVFoundation to check supported MIME types if possible
>diff --git a/Source/WebKit/ChangeLog b/Source/WebKit/ChangeLog
>index 87b2e441b7606673531fef5bb497dbfdb084eeaf..ab10cd4a8e6bd25d94dd049a3ecc16524b9abe33 100644
>--- a/Source/WebKit/ChangeLog
>+++ b/Source/WebKit/ChangeLog
>@@ -1,3 +1,82 @@
>+2018-05-24  Carlos Alberto Lopez Perez  <clopez@igalia.com>
>+
>+        [GTK][WPE] Memory pressure monitor doesn't reliable notify all the subprocesses
>+        https://bugs.webkit.org/show_bug.cgi?id=184261
>+
>+        Reviewed by Carlos Garcia Campos.
>+
>+        On Linux we had two implementations for getting notifications about memory pressure events:
>+        - The memory cgroup (called systemd here).
>+        - The UIProcess memory monitor (which delivered events via a shared eventfd)
>+
>+        The problem with the first is that it was usually not working on a standard machine due to
>+        the special permissions or configurations required for memory cgroups, so the second one
>+        (eventfd) was used as a fall-back in that case.
>+        But this eventfd method is racy with more than one WebKit child process and it wasn't
>+        reliably delivering the notifications.
>+
>+        This patch removes the memory cgroup implementation and modifies the UIProcess memory monitor
>+        to deliver the events via WebKit IPC. This simplifies the code a lot and allows us to have
>+        only one implementation that should work in any Linux machine.
>+
>+        The implementation now also triggers the event with information about the criticalness of it.
>+
>+        Previously a critical event was triggered always at a 95% of pressure.
>+        Now a non-critical one is triggered at 90% and critical remains at a 95%.
>+
>+        Start triggering events early should compensate the fact than triggering the event via WebKit IPC is
>+        a bit slower than doing that via an eventfd (or than listening on the memory cgroup event controller).
>+
>+        The events are delivered to all WebKit childs: WebProcess, NetworkProcess, StorageProcess, PluginProcess.
>+
>+        In the case of the StorageProcess a dummy controller is installed, which currently does nothing,
>+        but leaves a note for a future implementation and at least allows to trigger platformReleaseMemory()
>+        that on Linux/glibc should end calling malloc_trim()
>+
>+        * NetworkProcess/NetworkProcess.cpp:
>+        (WebKit::NetworkProcess::initializeNetworkProcess):
>+        * NetworkProcess/NetworkProcessCreationParameters.cpp:
>+        (WebKit::NetworkProcessCreationParameters::encode const):
>+        (WebKit::NetworkProcessCreationParameters::decode):
>+        * NetworkProcess/NetworkProcessCreationParameters.h:
>+        * PluginProcess/PluginProcess.cpp:
>+        (WebKit::PluginProcess::didReceiveMessage):
>+        (WebKit::PluginProcess::initializePluginProcess):
>+        * Shared/ChildProcess.cpp:
>+        (WebKit::ChildProcess::didReceiveMemoryPressureEvent):
>+        * Shared/ChildProcess.h:
>+        * Shared/ChildProcess.messages.in:
>+        * Shared/Plugins/PluginProcessCreationParameters.cpp:
>+        (WebKit::PluginProcessCreationParameters::encode const):
>+        (WebKit::PluginProcessCreationParameters::decode):
>+        * Shared/Plugins/PluginProcessCreationParameters.h:
>+        * Shared/WebProcessCreationParameters.cpp:
>+        (WebKit::WebProcessCreationParameters::encode const):
>+        (WebKit::WebProcessCreationParameters::decode):
>+        * Shared/WebProcessCreationParameters.h:
>+        * StorageProcess/StorageProcess.cpp:
>+        (WebKit::StorageProcess::initializeProcess):
>+        * UIProcess/Plugins/PluginProcessManager.cpp:
>+        (WebKit::PluginProcessManager::sendMemoryPressureEvent):
>+        * UIProcess/Plugins/PluginProcessManager.h:
>+        * UIProcess/Plugins/PluginProcessProxy.cpp:
>+        (WebKit::PluginProcessProxy::sendMemoryPressureEvent):
>+        (WebKit::PluginProcessProxy::didFinishLaunching):
>+        * UIProcess/Plugins/PluginProcessProxy.h:
>+        * UIProcess/WebProcessPool.cpp:
>+        (WebKit::WebProcessPool::sendMemoryPressureEvent):
>+        (WebKit::WebProcessPool::ensureNetworkProcess):
>+        (WebKit::WebProcessPool::initializeNewWebProcess):
>+        * UIProcess/WebProcessPool.h:
>+        (WebKit::WebProcessPool::sendToStorageProcess):
>+        * UIProcess/linux/MemoryPressureMonitor.cpp:
>+        (WebKit::pollIntervalForUsedMemoryPercentage): Fix equation for calculating the interval percentage.
>+        (WebKit::MemoryPressureMonitor::singleton):
>+        (WebKit::MemoryPressureMonitor::start):
>+        * UIProcess/linux/MemoryPressureMonitor.h:
>+        * WebProcess/WebProcess.cpp:
>+        (WebKit::WebProcess::initializeWebProcess):
>+
> 2018-05-24  Carlos Garcia Campos  <cgarcia@igalia.com>
> 
>         Unreviewed. Fix GTK+ input method unit tests after r232049.
>diff --git a/Source/WTF/wtf/MemoryPressureHandler.h b/Source/WTF/wtf/MemoryPressureHandler.h
>index 5d26356f3422b4c0a91183b8d62316c141b9790f..0039d054b0dbf06e6c6731081fb51479133dd551 100644
>--- a/Source/WTF/wtf/MemoryPressureHandler.h
>+++ b/Source/WTF/wtf/MemoryPressureHandler.h
>@@ -69,6 +69,10 @@ public:
> 
>     WTF_EXPORT_PRIVATE void setShouldUsePeriodicMemoryMonitor(bool);
> 
>+#if OS(LINUX)
>+    WTF_EXPORT_PRIVATE void triggerMemoryPressureEvent(bool isCritical);
>+#endif
>+
>     void setMemoryKillCallback(WTF::Function<void()>&& function) { m_memoryKillCallback = WTFMove(function); }
>     void setMemoryPressureStatusChangedCallback(WTF::Function<void(bool)>&& function) { m_memoryPressureStatusChangedCallback = WTFMove(function); }
>     void setDidExceedInactiveLimitWhileActiveCallback(WTF::Function<void()>&& function) { m_didExceedInactiveLimitWhileActiveCallback = WTFMove(function); }
>@@ -88,10 +92,6 @@ public:
>     }
>     void setUnderMemoryPressure(bool);
> 
>-#if OS(LINUX)
>-    void setMemoryPressureMonitorHandle(int fd);
>-#endif
>-
>     class ReliefLogger {
>     public:
>         explicit ReliefLogger(const char *log)
>@@ -169,26 +169,6 @@ private:
>     void doesExceedInactiveLimitWhileActive();
>     void doesNotExceedInactiveLimitWhileActive();
> 
>-#if OS(LINUX)
>-    class EventFDPoller {
>-        WTF_MAKE_NONCOPYABLE(EventFDPoller); WTF_MAKE_FAST_ALLOCATED;
>-    public:
>-        EventFDPoller(int fd, WTF::Function<void ()>&& notifyHandler);
>-        ~EventFDPoller();
>-
>-    private:
>-        void readAndNotify() const;
>-
>-        std::optional<int> m_fd;
>-        WTF::Function<void ()> m_notifyHandler;
>-#if USE(GLIB)
>-        GRefPtr<GSource> m_source;
>-#else
>-        RefPtr<Thread> m_thread;
>-#endif
>-    };
>-#endif
>-
>     WebsamProcessState m_processState { WebsamProcessState::Inactive };
> 
>     unsigned m_pageCount { 0 };
>@@ -213,13 +193,8 @@ private:
> #endif
> 
> #if OS(LINUX)
>-    std::optional<int> m_eventFD;
>-    std::optional<int> m_pressureLevelFD;
>-    std::unique_ptr<EventFDPoller> m_eventFDPoller;
>     RunLoop::Timer<MemoryPressureHandler> m_holdOffTimer;
>     void holdOffTimerFired();
>-    void logErrorAndCloseFDs(const char* error);
>-    bool tryEnsureEventFD();
> #endif
> };
> 
>diff --git a/Source/WTF/wtf/linux/MemoryPressureHandlerLinux.cpp b/Source/WTF/wtf/linux/MemoryPressureHandlerLinux.cpp
>index 8e85f58caf49df9f52da7ba3db1ac05b32a40bde..14f49989abbff418ad7fb863cc62dca27b64336f 100644
>--- a/Source/WTF/wtf/linux/MemoryPressureHandlerLinux.cpp
>+++ b/Source/WTF/wtf/linux/MemoryPressureHandlerLinux.cpp
>@@ -1,6 +1,7 @@
> /*
>  * Copyright (C) 2011, 2012 Apple Inc. All Rights Reserved.
>  * Copyright (C) 2014 Raspberry Pi Foundation. All Rights Reserved.
>+ * Copyright (C) 2018 Igalia S.L.
>  *
>  * Redistribution and use in source and binary forms, with or without
>  * modification, are permitted provided that the following conditions
>@@ -29,23 +30,13 @@
> 
> #if OS(LINUX)
> 
>-#include <errno.h>
>-#include <fcntl.h>
> #include <malloc.h>
>-#include <sys/eventfd.h>
>-#include <sys/stat.h>
>-#include <sys/types.h>
> #include <unistd.h>
> #include <wtf/MainThread.h>
> #include <wtf/MemoryFootprint.h>
> #include <wtf/linux/CurrentProcessMemoryStatus.h>
> #include <wtf/text/WTFString.h>
> 
>-#if USE(GLIB)
>-#include <glib-unix.h>
>-#include <wtf/glib/RunLoopSourcePriority.h>
>-#endif
>-
> #define LOG_CHANNEL_PREFIX Log
> 
> namespace WTF {
>@@ -63,160 +54,27 @@ static const Seconds s_maximumHoldOffTime { 30_s };
> static const size_t s_minimumBytesFreedToUseMinimumHoldOffTime = 1 * MB;
> static const unsigned s_holdOffMultiplier = 20;
> 
>-static const char* s_cgroupMemoryPressureLevel = "/sys/fs/cgroup/memory/memory.pressure_level";
>-static const char* s_cgroupEventControl = "/sys/fs/cgroup/memory/cgroup.event_control";
>-
>-#if USE(GLIB)
>-typedef struct {
>-    GSource source;
>-    gpointer fdTag;
>-    GIOCondition condition;
>-} EventFDSource;
>-
>-static const unsigned eventFDSourceCondition = G_IO_IN | G_IO_HUP | G_IO_ERR | G_IO_NVAL;
>-
>-static GSourceFuncs eventFDSourceFunctions = {
>-    nullptr, // prepare
>-    nullptr, // check
>-    // dispatch
>-    [](GSource* source, GSourceFunc callback, gpointer userData) -> gboolean
>-    {
>-        EventFDSource* eventFDSource = reinterpret_cast<EventFDSource*>(source);
>-        unsigned events = g_source_query_unix_fd(source, eventFDSource->fdTag) & eventFDSourceCondition;
>-        if (events & G_IO_HUP || events & G_IO_ERR || events & G_IO_NVAL)
>-            return G_SOURCE_REMOVE;
>-
>-        gboolean returnValue = G_SOURCE_CONTINUE;
>-        if (events & G_IO_IN)
>-            returnValue = callback(userData);
>-        g_source_set_ready_time(source, -1);
>-        return returnValue;
>-    },
>-    nullptr, // finalize
>-    nullptr, // closure_callback
>-    nullptr, // closure_marshall
>-};
>-#endif
>-
>-MemoryPressureHandler::EventFDPoller::EventFDPoller(int fd, WTF::Function<void ()>&& notifyHandler)
>-    : m_fd(fd)
>-    , m_notifyHandler(WTFMove(notifyHandler))
>+void MemoryPressureHandler::triggerMemoryPressureEvent(bool isCritical)
> {
>-#if USE(GLIB)
>-    m_source = adoptGRef(g_source_new(&eventFDSourceFunctions, sizeof(EventFDSource)));
>-    g_source_set_priority(m_source.get(), RunLoopSourcePriority::MemoryPressureHandlerTimer);
>-    g_source_set_name(m_source.get(), "WTF: MemoryPressureHandler");
>-    if (!g_unix_set_fd_nonblocking(m_fd.value(), TRUE, nullptr)) {
>-        LOG(MemoryPressure, "Failed to set eventfd nonblocking");
>-        return;
>-    }
>-
>-    EventFDSource* eventFDSource = reinterpret_cast<EventFDSource*>(m_source.get());
>-    eventFDSource->fdTag = g_source_add_unix_fd(m_source.get(), m_fd.value(), static_cast<GIOCondition>(eventFDSourceCondition));
>-    g_source_set_callback(m_source.get(), [](gpointer userData) -> gboolean {
>-        static_cast<EventFDPoller*>(userData)->readAndNotify();
>-        return G_SOURCE_REMOVE;
>-    }, this, nullptr);
>-    g_source_attach(m_source.get(), nullptr);
>-#else
>-    m_thread = Thread::create("WTF: MemoryPressureHandler",
>-        [this] {
>-            readAndNotify();
>-        });
>-#endif
>-}
>-
>-MemoryPressureHandler::EventFDPoller::~EventFDPoller()
>-{
>-    m_fd = std::nullopt;
>-#if USE(GLIB)
>-    g_source_destroy(m_source.get());
>-#else
>-    m_thread->detach();
>-#endif
>-}
>-
>-static inline bool isFatalReadError(int error)
>-{
>-#if USE(GLIB)
>-    // We don't really need to read the buffer contents, if the poller
>-    // notified us, but read would block or is no longer available, is
>-    // enough to trigger the memory pressure handler.
>-    return error != EAGAIN && error != EWOULDBLOCK;
>-#else
>-    return true;
>-#endif
>-}
>-
>-void MemoryPressureHandler::EventFDPoller::readAndNotify() const
>-{
>-    if (!m_fd) {
>-        LOG(MemoryPressure, "Invalidate eventfd.");
>+    if (!m_installed)
>         return;
>-    }
> 
>-    uint64_t buffer;
>-    if (read(m_fd.value(), &buffer, sizeof(buffer)) == -1) {
>-        if (isFatalReadError(errno)) {
>-            LOG(MemoryPressure, "Failed to read eventfd.");
>-            return;
>-        }
>-    }
>+    if (ReliefLogger::loggingEnabled())
>+        LOG(MemoryPressure, "Got memory pressure notification (%s)", isCritical ? "critical" : "non-critical");
> 
>-    m_notifyHandler();
>-}
>+    setUnderMemoryPressure(true);
> 
>-inline void MemoryPressureHandler::logErrorAndCloseFDs(const char* log)
>-{
>-    if (log)
>-        LOG(MemoryPressure, "%s, error : %m", log);
>-
>-    if (m_eventFD) {
>-        close(m_eventFD.value());
>-        m_eventFD = std::nullopt;
>-    }
>-    if (m_pressureLevelFD) {
>-        close(m_pressureLevelFD.value());
>-        m_pressureLevelFD = std::nullopt;
>-    }
>-}
>-
>-bool MemoryPressureHandler::tryEnsureEventFD()
>-{
>-    if (m_eventFD)
>-        return true;
>-
>-    // Try to use cgroups instead.
>-    int fd = eventfd(0, EFD_CLOEXEC);
>-    if (fd == -1) {
>-        LOG(MemoryPressure, "eventfd() failed: %m");
>-        return false;
>-    }
>-    m_eventFD = fd;
>-
>-    fd = open(s_cgroupMemoryPressureLevel, O_CLOEXEC | O_RDONLY);
>-    if (fd == -1) {
>-        logErrorAndCloseFDs("Failed to open memory.pressure_level");
>-        return false;
>-    }
>-    m_pressureLevelFD = fd;
>-
>-    fd = open(s_cgroupEventControl, O_CLOEXEC | O_WRONLY);
>-    if (fd == -1) {
>-        logErrorAndCloseFDs("Failed to open cgroup.event_control");
>-        return false;
>-    }
>+    if (isMainThread())
>+        respondToMemoryPressure(isCritical ? Critical::Yes : Critical::No);
>+    else
>+        RunLoop::main().dispatch([this, isCritical] {
>+            respondToMemoryPressure(isCritical ? Critical::Yes : Critical::No);
>+        });
> 
>-    char line[128] = {0, };
>-    if (snprintf(line, sizeof(line), "%d %d low", m_eventFD.value(), m_pressureLevelFD.value()) < 0
>-        || write(fd, line, strlen(line) + 1) < 0) {
>-        logErrorAndCloseFDs("Failed to write cgroup.event_control");
>-        close(fd);
>-        return false;
>-    }
>-    close(fd);
>+    if (ReliefLogger::loggingEnabled() && isUnderMemoryPressure())
>+        LOG(MemoryPressure, "System is no longer under memory pressure.");
> 
>-    return true;
>+    setUnderMemoryPressure(false);
> }
> 
> void MemoryPressureHandler::install()
>@@ -224,28 +82,6 @@ void MemoryPressureHandler::install()
>     if (m_installed || m_holdOffTimer.isActive())
>         return;
> 
>-    if (!tryEnsureEventFD())
>-        return;
>-
>-    m_eventFDPoller = std::make_unique<EventFDPoller>(m_eventFD.value(), [this] {
>-        // FIXME: Current memcg does not provide any way for users to know how serious the memory pressure is.
>-        // So we assume all notifications from memcg are critical for now. If memcg had better inferfaces
>-        // to get a detailed memory pressure level in the future, we should update here accordingly.
>-        bool critical = true;
>-        if (ReliefLogger::loggingEnabled())
>-            LOG(MemoryPressure, "Got memory pressure notification (%s)", critical ? "critical" : "non-critical");
>-
>-        setUnderMemoryPressure(critical);
>-        if (isMainThread())
>-            respondToMemoryPressure(critical ? Critical::Yes : Critical::No);
>-        else
>-            RunLoop::main().dispatch([this, critical] { respondToMemoryPressure(critical ? Critical::Yes : Critical::No); });
>-    });
>-
>-    if (ReliefLogger::loggingEnabled() && isUnderMemoryPressure())
>-        LOG(MemoryPressure, "System is no longer under memory pressure.");
>-
>-    setUnderMemoryPressure(false);
>     m_installed = true;
> }
> 
>@@ -255,18 +91,6 @@ void MemoryPressureHandler::uninstall()
>         return;
> 
>     m_holdOffTimer.stop();
>-    m_eventFDPoller = nullptr;
>-
>-    if (m_pressureLevelFD) {
>-        close(m_pressureLevelFD.value());
>-        m_pressureLevelFD = std::nullopt;
>-
>-        // Only close the eventFD used for cgroups.
>-        if (m_eventFD) {
>-            close(m_eventFD.value());
>-            m_eventFD = std::nullopt;
>-        }
>-    }
> 
>     m_installed = false;
> }
>@@ -318,11 +142,6 @@ std::optional<MemoryPressureHandler::ReliefLogger::MemoryUsage> MemoryPressureHa
>     return MemoryUsage {processMemoryUsage(), physical};
> }
> 
>-void MemoryPressureHandler::setMemoryPressureMonitorHandle(int fd)
>-{
>-    ASSERT(!m_eventFD);
>-    m_eventFD = fd;
>-}
> 
> } // namespace WTF
> 
>diff --git a/Source/WebKit/NetworkProcess/NetworkProcess.cpp b/Source/WebKit/NetworkProcess/NetworkProcess.cpp
>index 7f0b5f8d46d0976b0e357340eb00a6cddcc46e4f..a4bc45e19d17d9ceac214f3e5d5b4ac08b93713c 100644
>--- a/Source/WebKit/NetworkProcess/NetworkProcess.cpp
>+++ b/Source/WebKit/NetworkProcess/NetworkProcess.cpp
>@@ -232,10 +232,6 @@ void NetworkProcess::initializeNetworkProcess(NetworkProcessCreationParameters&&
>     m_loadThrottleLatency = parameters.loadThrottleLatency;
>     if (!m_suppressMemoryPressureHandler) {
>         auto& memoryPressureHandler = MemoryPressureHandler::singleton();
>-#if OS(LINUX)
>-        if (parameters.memoryPressureMonitorHandle.fileDescriptor() != -1)
>-            memoryPressureHandler.setMemoryPressureMonitorHandle(parameters.memoryPressureMonitorHandle.releaseFileDescriptor());
>-#endif
>         memoryPressureHandler.setLowMemoryHandler([this] (Critical critical, Synchronous) {
>             lowMemoryHandler(critical);
>         });
>diff --git a/Source/WebKit/NetworkProcess/NetworkProcessCreationParameters.cpp b/Source/WebKit/NetworkProcess/NetworkProcessCreationParameters.cpp
>index d61cff8d00a474d7308ab38c4a8e633feafeefb5..f855293396efaba94a9fb01bad558314c7f7e238 100644
>--- a/Source/WebKit/NetworkProcess/NetworkProcessCreationParameters.cpp
>+++ b/Source/WebKit/NetworkProcess/NetworkProcessCreationParameters.cpp
>@@ -100,9 +100,6 @@ void NetworkProcessCreationParameters::encode(IPC::Encoder& encoder) const
> #if HAVE(CFNETWORK_STORAGE_PARTITIONING) && !RELEASE_LOG_DISABLED
>     encoder << logCookieInformation;
> #endif
>-#if OS(LINUX)
>-    encoder << memoryPressureMonitorHandle;
>-#endif
> #if ENABLE(NETWORK_CAPTURE)
>     encoder << recordReplayMode;
>     encoder << recordReplayCacheLocation;
>@@ -254,11 +251,6 @@ bool NetworkProcessCreationParameters::decode(IPC::Decoder& decoder, NetworkProc
>         return false;
> #endif
> 
>-#if OS(LINUX)
>-    if (!decoder.decode(result.memoryPressureMonitorHandle))
>-        return false;
>-#endif
>-
> #if ENABLE(NETWORK_CAPTURE)
>     if (!decoder.decode(result.recordReplayMode))
>         return false;
>diff --git a/Source/WebKit/NetworkProcess/NetworkProcessCreationParameters.h b/Source/WebKit/NetworkProcess/NetworkProcessCreationParameters.h
>index 25bc08f55cf7a4f6e71e901fb002635b5d945944..5d0fe13a5e6a75d80eb79c5f4bbbdd6b2b617bea 100644
>--- a/Source/WebKit/NetworkProcess/NetworkProcessCreationParameters.h
>+++ b/Source/WebKit/NetworkProcess/NetworkProcessCreationParameters.h
>@@ -25,7 +25,6 @@
> 
> #pragma once
> 
>-#include "Attachment.h"
> #include "CacheModel.h"
> #include "NetworkSessionCreationParameters.h"
> #include "SandboxExtension.h"
>@@ -116,10 +115,6 @@ struct NetworkProcessCreationParameters {
>     bool logCookieInformation { false };
> #endif
> 
>-#if OS(LINUX)
>-    IPC::Attachment memoryPressureMonitorHandle;
>-#endif
>-
> #if ENABLE(NETWORK_CAPTURE)
>     String recordReplayMode;
>     String recordReplayCacheLocation;
>diff --git a/Source/WebKit/PluginProcess/PluginProcess.cpp b/Source/WebKit/PluginProcess/PluginProcess.cpp
>index 1cd3075b6bc27aa8257b43635a670238d6b8c93c..a41e64c40ae8acf97d29ae998c13dcd82a004ddb 100644
>--- a/Source/WebKit/PluginProcess/PluginProcess.cpp
>+++ b/Source/WebKit/PluginProcess/PluginProcess.cpp
>@@ -30,6 +30,7 @@
> 
> #include "ArgumentCoders.h"
> #include "Attachment.h"
>+#include "ChildProcessMessages.h"
> #include "NetscapePlugin.h"
> #include "NetscapePluginModule.h"
> #include "PluginProcessConnectionMessages.h"
>@@ -116,6 +117,11 @@ bool PluginProcess::shouldTerminate()
> 
> void PluginProcess::didReceiveMessage(IPC::Connection& connection, IPC::Decoder& decoder)
> {
>+    if (decoder.messageReceiverName() == Messages::ChildProcess::messageReceiverName()) {
>+        ChildProcess::didReceiveMessage(connection, decoder);
>+        return;
>+    }
>+
>     didReceivePluginProcessMessage(connection, decoder);
> }
> 
>@@ -124,10 +130,6 @@ void PluginProcess::initializePluginProcess(PluginProcessCreationParameters&& pa
>     ASSERT(!m_pluginModule);
> 
>     auto& memoryPressureHandler = MemoryPressureHandler::singleton();
>-#if OS(LINUX)
>-    if (parameters.memoryPressureMonitorHandle.fileDescriptor() != -1)
>-        memoryPressureHandler.setMemoryPressureMonitorHandle(parameters.memoryPressureMonitorHandle.releaseFileDescriptor());
>-#endif
>     memoryPressureHandler.setLowMemoryHandler([this] (Critical, Synchronous) {
>         if (shouldTerminate())
>             terminate();
>diff --git a/Source/WebKit/Shared/ChildProcess.cpp b/Source/WebKit/Shared/ChildProcess.cpp
>index 0b2cab7976967ab698ab1f9f666283fecdbc9997..4534243835d0f0ced3bb839562bf59fd565e90bf 100644
>--- a/Source/WebKit/Shared/ChildProcess.cpp
>+++ b/Source/WebKit/Shared/ChildProcess.cpp
>@@ -35,6 +35,10 @@
> #include <unistd.h>
> #endif
> 
>+#if OS(LINUX)
>+#include <wtf/MemoryPressureHandler.h>
>+#endif
>+
> using namespace WebCore;
> 
> namespace WebKit {
>@@ -215,6 +219,14 @@ void ChildProcess::didReceiveInvalidMessage(IPC::Connection&, IPC::StringReferen
>     WTFLogAlways("Received invalid message: '%s::%s'", messageReceiverName.toString().data(), messageName.toString().data());
>     CRASH();
> }
>+
>+#if OS(LINUX)
>+void ChildProcess::didReceiveMemoryPressureEvent(bool isCritical)
>+{
>+    MemoryPressureHandler::singleton().triggerMemoryPressureEvent(isCritical);
>+}
> #endif
> 
>+#endif // !PLATFORM(COCOA)
>+
> } // namespace WebKit
>diff --git a/Source/WebKit/Shared/ChildProcess.h b/Source/WebKit/Shared/ChildProcess.h
>index bfd16ea45eb81fff60f6f23fec0657e37f9ab281..b35c9f2e3f3fa87e2dfbee1b0afc979b98a2f8f1 100644
>--- a/Source/WebKit/Shared/ChildProcess.h
>+++ b/Source/WebKit/Shared/ChildProcess.h
>@@ -107,6 +107,9 @@ protected:
>     void didReceiveMessage(IPC::Connection&, IPC::Decoder&) override;
> 
>     void registerURLSchemeServiceWorkersCanHandle(const String&) const;
>+#if OS(LINUX)
>+    void didReceiveMemoryPressureEvent(bool isCritical);
>+#endif
> 
> private:
>     // IPC::MessageSender
>diff --git a/Source/WebKit/Shared/ChildProcess.messages.in b/Source/WebKit/Shared/ChildProcess.messages.in
>index 1dd1b1a32726a5835217dda0690a16ef2fb353e7..18cbcd8501078a90fb372d0cd9df6fa5f25829bb 100644
>--- a/Source/WebKit/Shared/ChildProcess.messages.in
>+++ b/Source/WebKit/Shared/ChildProcess.messages.in
>@@ -24,4 +24,8 @@ messages -> ChildProcess {
>     ShutDown()
>     RegisterURLSchemeServiceWorkersCanHandle(String scheme)
>     SetProcessSuppressionEnabled(bool flag)
>+
>+#if OS(LINUX)
>+    void DidReceiveMemoryPressureEvent(bool isCritical)
>+#endif
> }
>diff --git a/Source/WebKit/Shared/Plugins/PluginProcessCreationParameters.cpp b/Source/WebKit/Shared/Plugins/PluginProcessCreationParameters.cpp
>index 7bd78b6c3305525768d328c2f10c92912c3f2272..5e44035a3eab8220b5f1aecb0ac59633ce8efdb0 100644
>--- a/Source/WebKit/Shared/Plugins/PluginProcessCreationParameters.cpp
>+++ b/Source/WebKit/Shared/Plugins/PluginProcessCreationParameters.cpp
>@@ -49,9 +49,6 @@ void PluginProcessCreationParameters::encode(IPC::Encoder& encoder) const
>     encoder << acceleratedCompositingPort;
>     IPC::encode(encoder, networkATSContext.get());
> #endif
>-#if OS(LINUX)
>-    encoder << memoryPressureMonitorHandle;
>-#endif
> }
> 
> bool PluginProcessCreationParameters::decode(IPC::Decoder& decoder, PluginProcessCreationParameters& result)
>@@ -70,10 +67,6 @@ bool PluginProcessCreationParameters::decode(IPC::Decoder& decoder, PluginProces
>     if (!IPC::decode(decoder, result.networkATSContext))
>         return false;
> #endif
>-#if OS(LINUX)
>-    if (!decoder.decode(result.memoryPressureMonitorHandle))
>-        return false;
>-#endif
> 
>     return true;
> }
>diff --git a/Source/WebKit/Shared/Plugins/PluginProcessCreationParameters.h b/Source/WebKit/Shared/Plugins/PluginProcessCreationParameters.h
>index 186cb3b9889fb8d81d126bc0aecf8a310646e4c5..d326880a9477b3abeb3ab3960aad0bac12a53a8f 100644
>--- a/Source/WebKit/Shared/Plugins/PluginProcessCreationParameters.h
>+++ b/Source/WebKit/Shared/Plugins/PluginProcessCreationParameters.h
>@@ -27,7 +27,6 @@
> 
> #if ENABLE(NETSCAPE_PLUGIN_API)
> 
>-#include "Attachment.h"
> #include "PluginProcessAttributes.h"
> #include <wtf/Seconds.h>
> 
>@@ -58,9 +57,6 @@ struct PluginProcessCreationParameters {
>     WTF::MachSendRight acceleratedCompositingPort;
>     RetainPtr<CFDataRef> networkATSContext;
> #endif
>-#if OS(LINUX)
>-    IPC::Attachment memoryPressureMonitorHandle;
>-#endif
> };
> 
> } // namespace WebKit
>diff --git a/Source/WebKit/Shared/WebProcessCreationParameters.cpp b/Source/WebKit/Shared/WebProcessCreationParameters.cpp
>index 801e610d5e02a84156febbbdd69f6c6f779bee0f..483d47c97962fd42820f1524756a1c5519e23cee 100644
>--- a/Source/WebKit/Shared/WebProcessCreationParameters.cpp
>+++ b/Source/WebKit/Shared/WebProcessCreationParameters.cpp
>@@ -139,10 +139,6 @@ void WebProcessCreationParameters::encode(IPC::Encoder& encoder) const
>     IPC::encode(encoder, networkATSContext.get());
> #endif
> 
>-#if OS(LINUX)
>-    encoder << memoryPressureMonitorHandle;
>-#endif
>-
> #if PLATFORM(WAYLAND)
>     encoder << waylandCompositorDisplayName;
> #endif
>@@ -385,11 +381,6 @@ bool WebProcessCreationParameters::decode(IPC::Decoder& decoder, WebProcessCreat
>         return false;
> #endif
> 
>-#if OS(LINUX)
>-    if (!decoder.decode(parameters.memoryPressureMonitorHandle))
>-        return false;
>-#endif
>-
> #if PLATFORM(WAYLAND)
>     if (!decoder.decode(parameters.waylandCompositorDisplayName))
>         return false;
>diff --git a/Source/WebKit/Shared/WebProcessCreationParameters.h b/Source/WebKit/Shared/WebProcessCreationParameters.h
>index e250237e48d112554e38f542125ec238eeca0c97..6e1cce91a7779e89104eef76bd3b7961a8813e55 100644
>--- a/Source/WebKit/Shared/WebProcessCreationParameters.h
>+++ b/Source/WebKit/Shared/WebProcessCreationParameters.h
>@@ -173,10 +173,6 @@ struct WebProcessCreationParameters {
>     RetainPtr<CFDataRef> networkATSContext;
> #endif
> 
>-#if OS(LINUX)
>-    IPC::Attachment memoryPressureMonitorHandle;
>-#endif
>-
> #if PLATFORM(WAYLAND)
>     String waylandCompositorDisplayName;
> #endif
>diff --git a/Source/WebKit/StorageProcess/StorageProcess.cpp b/Source/WebKit/StorageProcess/StorageProcess.cpp
>index 6a98d1ad8d910b8ba40368a88b0a2eba696ce609..5782a2ae64ee59db9e1cabce335d04b29a3b4219 100644
>--- a/Source/WebKit/StorageProcess/StorageProcess.cpp
>+++ b/Source/WebKit/StorageProcess/StorageProcess.cpp
>@@ -49,6 +49,8 @@
> #include <wtf/CallbackAggregator.h>
> #include <wtf/CrossThreadTask.h>
> #include <wtf/MainThread.h>
>+#include <wtf/MemoryPressureHandler.h>
>+
> 
> #if ENABLE(SERVICE_WORKER)
> #include "WebSWServerToContextConnectionMessages.h"
>@@ -555,6 +557,14 @@ void StorageProcess::disableServiceWorkerProcessTerminationDelay()
> #if !PLATFORM(COCOA)
> void StorageProcess::initializeProcess(const ChildProcessInitializationParameters&)
> {
>+#if OS(LINUX)
>+    auto& memoryPressureHandler = MemoryPressureHandler::singleton();
>+    memoryPressureHandler.setLowMemoryHandler([this] (Critical, Synchronous) {
>+        // FIXME: no lowMemoryHandler() implemented for StorageProcess currently.
>+        // But at least define this setLowMemoryHandler() empty so platformReleaseMemory is called.
>+    });
>+    memoryPressureHandler.install();
>+#endif
> }
> 
> void StorageProcess::initializeProcessName(const ChildProcessInitializationParameters&)
>@@ -564,6 +574,6 @@ void StorageProcess::initializeProcessName(const ChildProcessInitializationParam
> void StorageProcess::initializeSandbox(const ChildProcessInitializationParameters&, SandboxInitializationParameters&)
> {
> }
>-#endif
>+#endif // !PLATFORM(COCOA)
> 
> } // namespace WebKit
>diff --git a/Source/WebKit/UIProcess/Plugins/PluginProcessManager.cpp b/Source/WebKit/UIProcess/Plugins/PluginProcessManager.cpp
>index 139fa5ac953b9cc0eca49f44a93d6349163b4cb1..57662d99541f0b22bedca4ef6a1456b5d231f53e 100644
>--- a/Source/WebKit/UIProcess/Plugins/PluginProcessManager.cpp
>+++ b/Source/WebKit/UIProcess/Plugins/PluginProcessManager.cpp
>@@ -131,6 +131,14 @@ PluginProcessProxy* PluginProcessManager::getPluginProcess(uint64_t pluginProces
>     return nullptr;
> }
> 
>+#if OS(LINUX)
>+void PluginProcessManager::sendMemoryPressureEvent(bool isCritical)
>+{
>+    for (auto& pluginProcess : m_pluginProcesses)
>+        pluginProcess->sendMemoryPressureEvent(isCritical);
>+}
>+#endif
>+
> PluginProcessProxy* PluginProcessManager::getOrCreatePluginProcess(uint64_t pluginProcessToken)
> {
>     if (auto existingProcess = getPluginProcess(pluginProcessToken))
>diff --git a/Source/WebKit/UIProcess/Plugins/PluginProcessManager.h b/Source/WebKit/UIProcess/Plugins/PluginProcessManager.h
>index 5dcdd2c5f127571b825683ba0e4c38a397766969..a5c3fbead0906c934690ae3a3b9a6726fd58a57a 100644
>--- a/Source/WebKit/UIProcess/Plugins/PluginProcessManager.h
>+++ b/Source/WebKit/UIProcess/Plugins/PluginProcessManager.h
>@@ -64,6 +64,10 @@ public:
>     void deleteWebsiteData(const PluginModuleInfo&, WallTime modifiedSince, WTF::Function<void ()>&& completionHandler);
>     void deleteWebsiteDataForHostNames(const PluginModuleInfo&, const Vector<String>& hostNames, WTF::Function<void ()>&& completionHandler);
> 
>+#if OS(LINUX)
>+    void sendMemoryPressureEvent(bool isCritical);
>+#endif
>+
> #if PLATFORM(COCOA)
>     inline ProcessSuppressionDisabledToken processSuppressionDisabledToken();
>     inline bool processSuppressionDisabled() const;
>diff --git a/Source/WebKit/UIProcess/Plugins/PluginProcessProxy.cpp b/Source/WebKit/UIProcess/Plugins/PluginProcessProxy.cpp
>index 4d0ddf8ea1aa44c5028495c30501191d7484c365..7a39f5b1aea9336d42a5cf215b10ed6c92335e44 100644
>--- a/Source/WebKit/UIProcess/Plugins/PluginProcessProxy.cpp
>+++ b/Source/WebKit/UIProcess/Plugins/PluginProcessProxy.cpp
>@@ -28,6 +28,7 @@
> 
> #if ENABLE(NETSCAPE_PLUGIN_API)
> 
>+#include "ChildProcessMessages.h"
> #include "PluginProcessConnectionManagerMessages.h"
> #include "PluginProcessCreationParameters.h"
> #include "PluginProcessManager.h"
>@@ -38,10 +39,6 @@
> #include <WebCore/NotImplemented.h>
> #include <wtf/RunLoop.h>
> 
>-#if OS(LINUX)
>-#include "MemoryPressureMonitor.h"
>-#endif
>-
> using namespace WebCore;
> 
> namespace WebKit {
>@@ -155,6 +152,16 @@ void PluginProcessProxy::deleteWebsiteDataForHostNames(const Vector<String>& hos
>     m_connection->send(Messages::PluginProcess::DeleteWebsiteDataForHostNames(hostNames, callbackID), 0);
> }
> 
>+#if OS(LINUX)
>+void PluginProcessProxy::sendMemoryPressureEvent(bool isCritical)
>+{
>+    if (state() == State::Launching)
>+        return;
>+
>+    m_connection->send(Messages::ChildProcess::DidReceiveMemoryPressureEvent(isCritical), 0);
>+}
>+#endif
>+
> void PluginProcessProxy::pluginProcessCrashedOrFailedToLaunch()
> {
>     // The plug-in process must have crashed or exited, send any pending sync replies we might have.
>@@ -234,11 +241,6 @@ void PluginProcessProxy::didFinishLaunching(ProcessLauncher*, IPC::Connection::I
>         parameters.terminationTimeout = shutdownTimeout;
>     }
> 
>-#if OS(LINUX)
>-    if (MemoryPressureMonitor::isEnabled())
>-        parameters.memoryPressureMonitorHandle = MemoryPressureMonitor::singleton().createHandle();
>-#endif
>-
>     platformInitializePluginProcess(parameters);
> 
>     // Initialize the plug-in host process.
>diff --git a/Source/WebKit/UIProcess/Plugins/PluginProcessProxy.h b/Source/WebKit/UIProcess/Plugins/PluginProcessProxy.h
>index 69c153decf61b40f89571ff2042bcc11cfa66fe3..9e86b85ba375b0abc3a81a30634ed3a23dfd3d03 100644
>--- a/Source/WebKit/UIProcess/Plugins/PluginProcessProxy.h
>+++ b/Source/WebKit/UIProcess/Plugins/PluginProcessProxy.h
>@@ -82,6 +82,10 @@ public:
>     void deleteWebsiteData(WallTime modifiedSince, WTF::Function<void ()>&& completionHandler);
>     void deleteWebsiteDataForHostNames(const Vector<String>& hostNames, WTF::Function<void ()>&& completionHandler);
> 
>+#if OS(LINUX)
>+    void sendMemoryPressureEvent(bool isCritical);
>+#endif
>+
>     bool isValid() const { return m_connection; }
> 
> #if PLUGIN_ARCHITECTURE(UNIX)
>diff --git a/Source/WebKit/UIProcess/WebProcessPool.cpp b/Source/WebKit/UIProcess/WebProcessPool.cpp
>index 12a6ddfc0874eaec97e002da603ad37e27429676..bf3bc98e4628d69d5519826be884f3c552b3be34 100644
>--- a/Source/WebKit/UIProcess/WebProcessPool.cpp
>+++ b/Source/WebKit/UIProcess/WebProcessPool.cpp
>@@ -49,6 +49,7 @@
> #include "NetworkProcessMessages.h"
> #include "NetworkProcessProxy.h"
> #include "PerActivityStateCPUUsageSampler.h"
>+#include "PluginProcessManager.h"
> #include "SandboxExtension.h"
> #include "ServiceWorkerProcessProxy.h"
> #include "StatisticsData.h"
>@@ -269,6 +270,10 @@ WebProcessPool::WebProcessPool(API::ProcessPoolConfiguration& configuration)
> 
>     platformInitialize();
> 
>+#if OS(LINUX)
>+    MemoryPressureMonitor::singleton().start();
>+#endif
>+
>     addMessageReceiver(Messages::WebProcessPool::messageReceiverName(), *this);
> 
>     // NOTE: These sub-objects must be initialized after m_messageReceiverMap..
>@@ -413,6 +418,18 @@ void WebProcessPool::fullKeyboardAccessModeChanged(bool fullKeyboardAccessEnable
>     sendToAllProcesses(Messages::WebProcess::FullKeyboardAccessModeChanged(fullKeyboardAccessEnabled));
> }
> 
>+#if OS(LINUX)
>+void WebProcessPool::sendMemoryPressureEvent(bool isCritical)
>+{
>+    sendToAllProcesses(Messages::ChildProcess::DidReceiveMemoryPressureEvent(isCritical));
>+    sendToNetworkingProcess(Messages::ChildProcess::DidReceiveMemoryPressureEvent(isCritical));
>+    sendToStorageProcess(Messages::ChildProcess::DidReceiveMemoryPressureEvent(isCritical));
>+#if ENABLE(NETSCAPE_PLUGIN_API)
>+    PluginProcessManager::singleton().sendMemoryPressureEvent(isCritical);
>+#endif
>+}
>+#endif
>+
> void WebProcessPool::textCheckerStateChanged()
> {
>     sendToAllProcesses(Messages::WebProcess::SetTextCheckerState(TextChecker::state()));
>@@ -490,11 +507,6 @@ NetworkProcessProxy& WebProcessPool::ensureNetworkProcess(WebsiteDataStore* with
>         SandboxExtension::createHandle(parentBundleDirectory, SandboxExtension::Type::ReadOnly, parameters.parentBundleDirectoryExtensionHandle);
> #endif
> 
>-#if OS(LINUX)
>-    if (MemoryPressureMonitor::isEnabled())
>-        parameters.memoryPressureMonitorHandle = MemoryPressureMonitor::singleton().createHandle();
>-#endif
>-
>     parameters.shouldUseTestingNetworkSession = m_shouldUseTestingNetworkSession;
>     parameters.presentingApplicationPID = m_configuration->presentingApplicationPID();
> 
>@@ -923,8 +935,6 @@ void WebProcessPool::initializeNewWebProcess(WebProcessProxy& process, WebsiteDa
> 
> #if OS(LINUX)
>     parameters.shouldEnableMemoryPressureReliefLogging = true;
>-    if (MemoryPressureMonitor::isEnabled())
>-        parameters.memoryPressureMonitorHandle = MemoryPressureMonitor::singleton().createHandle();
> #endif
> 
> #if PLATFORM(WAYLAND) && USE(EGL)
>diff --git a/Source/WebKit/UIProcess/WebProcessPool.h b/Source/WebKit/UIProcess/WebProcessPool.h
>index b5b5e4ac099a19708bda2adee5feb3f94b1e6a78..21d71f5f0a4c88d2996648fa6bc439ed1ee13fd8 100644
>--- a/Source/WebKit/UIProcess/WebProcessPool.h
>+++ b/Source/WebKit/UIProcess/WebProcessPool.h
>@@ -165,6 +165,7 @@ public:
>     template<typename T> void sendToNetworkingProcessRelaunchingIfNecessary(T&& message);
> 
>     // Sends the message to WebProcess or StorageProcess as approporiate for current process model.
>+    template<typename T> void sendToStorageProcess(T&& message);
>     template<typename T> void sendToStorageProcessRelaunchingIfNecessary(T&& message);
> 
>     void processDidFinishLaunching(WebProcessProxy*);
>@@ -313,7 +314,9 @@ public:
> #endif
> 
>     void fullKeyboardAccessModeChanged(bool fullKeyboardAccessEnabled);
>-
>+#if OS(LINUX)
>+    void sendMemoryPressureEvent(bool isCritical);
>+#endif
>     void textCheckerStateChanged();
> 
>     Ref<API::Dictionary> plugInAutoStartOriginHashes() const;
>@@ -714,6 +717,13 @@ void WebProcessPool::sendToNetworkingProcessRelaunchingIfNecessary(T&& message)
> }
> 
> template<typename T>
>+void WebProcessPool::sendToStorageProcess(T&& message)
>+{
>+    if (m_storageProcess && m_storageProcess->canSendMessage())
>+        m_storageProcess->send(std::forward<T>(message), 0);
>+}
>+
>+template<typename T>
> void WebProcessPool::sendToStorageProcessRelaunchingIfNecessary(T&& message)
> {
>     ensureStorageProcessAndWebsiteDataStore(nullptr);
>diff --git a/Source/WebKit/UIProcess/linux/MemoryPressureMonitor.cpp b/Source/WebKit/UIProcess/linux/MemoryPressureMonitor.cpp
>index 357d9936cffbf81005ccbb96a2580a5de9668687..9ed4b73cecbd8b9eb4aecddaa00651cabb33b499 100644
>--- a/Source/WebKit/UIProcess/linux/MemoryPressureMonitor.cpp
>+++ b/Source/WebKit/UIProcess/linux/MemoryPressureMonitor.cpp
>@@ -1,5 +1,5 @@
> /*
>- * Copyright (C) 2016 Igalia S.L.
>+ * Copyright (C) 2016, 2018 Igalia S.L.
>  *
>  * Redistribution and use in source and binary forms, with or without
>  * modification, are permitted provided that the following conditions
>@@ -28,15 +28,10 @@
> 
> #if OS(LINUX)
> 
>-#include "Attachment.h"
>-#include <errno.h>
>-#include <fcntl.h>
>-#include <mutex>
>+#include "WebProcessPool.h"
>+#include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
>-#include <sys/eventfd.h>
>-#include <sys/stat.h>
>-#include <sys/types.h>
> #include <unistd.h>
> #include <wtf/Threading.h>
> #include <wtf/UniStdExtras.h>
>@@ -48,8 +43,9 @@ static const size_t notSet = static_cast<size_t>(-1);
> static const Seconds s_minPollingInterval { 1_s };
> static const Seconds s_maxPollingInterval { 5_s };
> static const double s_minUsedMemoryPercentageForPolling = 50;
>-static const double s_maxUsedMemoryPercentageForPolling = 90;
>-static const int s_memoryPresurePercentageThreshold = 95;
>+static const double s_maxUsedMemoryPercentageForPolling = 85;
>+static const int s_memoryPresurePercentageThreshold = 90;
>+static const int s_memoryPresurePercentageThresholdCritical = 95;
> 
> static size_t lowWatermarkPages()
> {
>@@ -208,45 +204,22 @@ static inline Seconds pollIntervalForUsedMemoryPercentage(int usedPercentage)
>         return s_minPollingInterval;
> 
>     return s_minPollingInterval + (s_maxPollingInterval - s_minPollingInterval) *
>-        ((usedPercentage - s_minUsedMemoryPercentageForPolling) / (s_maxUsedMemoryPercentageForPolling - s_minUsedMemoryPercentageForPolling));
>-}
>-
>-static bool isSystemdMemoryPressureMonitorAvailable()
>-{
>-    int fd = open("/sys/fs/cgroup/memory/memory.pressure_level", O_CLOEXEC | O_RDONLY);
>-    if (fd == -1)
>-        return false;
>-    close(fd);
>-
>-    fd = open("/sys/fs/cgroup/memory/cgroup.event_control", O_CLOEXEC | O_WRONLY);
>-    if (fd == -1)
>-        return false;
>-    close(fd);
>-
>-    return true;
>-}
>-
>-bool MemoryPressureMonitor::isEnabled()
>-{
>-    static std::once_flag onceFlag;
>-    static bool enabled;
>-    std::call_once(onceFlag, [] { enabled = !isSystemdMemoryPressureMonitorAvailable(); });
>-    return enabled;
>+        ((s_maxUsedMemoryPercentageForPolling - usedPercentage) / (s_maxUsedMemoryPercentageForPolling - s_minUsedMemoryPercentageForPolling));
> }
> 
> MemoryPressureMonitor& MemoryPressureMonitor::singleton()
> {
>-    ASSERT(isEnabled());
>     static NeverDestroyed<MemoryPressureMonitor> memoryMonitor;
>     return memoryMonitor;
> }
> 
>-MemoryPressureMonitor::MemoryPressureMonitor()
>-    : m_eventFD(eventfd(0, EFD_CLOEXEC))
>+void MemoryPressureMonitor::start()
> {
>-    if (m_eventFD == -1)
>+    if (m_started)
>         return;
> 
>+    m_started = true;
>+
>     Thread::create("MemoryPressureMonitor", [this] {
>         Seconds pollInterval = s_maxPollingInterval;
>         while (true) {
>@@ -259,26 +232,15 @@ MemoryPressureMonitor::MemoryPressureMonitor()
>             }
> 
>             if (usedPercentage >= s_memoryPresurePercentageThreshold) {
>-                uint64_t fdEvent = 1;
>-                ssize_t bytesWritten = write(m_eventFD, &fdEvent, sizeof(uint64_t));
>-                if (bytesWritten != sizeof(uint64_t)) {
>-                    WTFLogAlways("Error writing to MemoryPressureMonitor eventFD: %s", strerror(errno));
>-                    break;
>-                }
>+                bool isCritical = (usedPercentage >= s_memoryPresurePercentageThresholdCritical);
>+                for (auto* processPool : WebProcessPool::allProcessPools())
>+                    processPool->sendMemoryPressureEvent(isCritical);
>             }
>             pollInterval = pollIntervalForUsedMemoryPercentage(usedPercentage);
>         }
>-        close(m_eventFD);
>     })->detach();
> }
> 
>-IPC::Attachment MemoryPressureMonitor::createHandle() const
>-{
>-    int duplicatedHandle = dupCloseOnExec(m_eventFD);
>-    if (duplicatedHandle == -1)
>-        return { };
>-    return IPC::Attachment(duplicatedHandle);
>-}
> 
> } // namespace WebKit
> 
>diff --git a/Source/WebKit/UIProcess/linux/MemoryPressureMonitor.h b/Source/WebKit/UIProcess/linux/MemoryPressureMonitor.h
>index e250c855171f839f438966a7b6d85c995dfa5fc0..64c1d7d78613b9cf69249ea6c4af0d65f5a73913 100644
>--- a/Source/WebKit/UIProcess/linux/MemoryPressureMonitor.h
>+++ b/Source/WebKit/UIProcess/linux/MemoryPressureMonitor.h
>@@ -41,16 +41,13 @@ class MemoryPressureMonitor {
>     friend NeverDestroyed<MemoryPressureMonitor>;
> public:
>     static MemoryPressureMonitor& singleton();
>-    static bool isEnabled();
>+    void start();
> 
>     ~MemoryPressureMonitor();
> 
>-    IPC::Attachment createHandle() const;
>-
> private:
>-    MemoryPressureMonitor();
>-
>-    int m_eventFD { -1 };
>+    MemoryPressureMonitor() = default;
>+    bool m_started { false };
> };
> 
> } // namespace WebKit
>diff --git a/Source/WebKit/WebProcess/WebProcess.cpp b/Source/WebKit/WebProcess/WebProcess.cpp
>index 0e8370485aa99da8e3e41b91cdf2367c2933204e..50800d03ef72809d425d3dfb100f5e7f9933b792 100644
>--- a/Source/WebKit/WebProcess/WebProcess.cpp
>+++ b/Source/WebKit/WebProcess/WebProcess.cpp
>@@ -270,8 +270,6 @@ void WebProcess::initializeWebProcess(WebProcessCreationParameters&& parameters)
>     WebCore::setPresentingApplicationPID(parameters.presentingApplicationPID);
> 
> #if OS(LINUX)
>-    if (parameters.memoryPressureMonitorHandle.fileDescriptor() != -1)
>-        MemoryPressureHandler::singleton().setMemoryPressureMonitorHandle(parameters.memoryPressureMonitorHandle.releaseFileDescriptor());
>     MemoryPressureHandler::ReliefLogger::setLoggingEnabled(parameters.shouldEnableMemoryPressureReliefLogging);
> #endif
>

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Attachments on bug 184261: 337074 | 340167 | 340174 | 341087 | 341092 | 341194 | 341208