Changeset 128818 in webkit

Timestamp:

Sep 17, 2012 4:00:32 PM (12 years ago)

Author:

Csaba Osztrogonác

Message:

Unreviewed, rolling out r128796.
​http://trac.webkit.org/changeset/128796
​https://bugs.webkit.org/show_bug.cgi?id=96966

It broke everything (Requested by Ossy_NIGHT on #webkit).

Patch by Sheriff Bot <​webkit.review.bot@gmail.com> on 2012-09-17

• wtf/OSAllocatorPosix.cpp:

(WTF::OSAllocator::reserveUncommitted):
(WTF::OSAllocator::reserveAndCommit):
(WTF::OSAllocator::commit):
(WTF::OSAllocator::decommit):

Location:

trunk/Source/WTF

Files:

• ChangeLog (modified) (1 diff)
• wtf/OSAllocatorPosix.cpp (modified) (4 diffs)

trunk/Source/WTF/ChangeLog

@@ +1 @@
+2012-09-17  Sheriff Bot  <webkit.review.bot@gmail.com>
+
+        Unreviewed, rolling out r128796.
+        http://trac.webkit.org/changeset/128796
+        https://bugs.webkit.org/show_bug.cgi?id=96966
+
+        It broke everything (Requested by Ossy_NIGHT on #webkit).
+
+        * wtf/OSAllocatorPosix.cpp:
+        (WTF::OSAllocator::reserveUncommitted):
+        (WTF::OSAllocator::reserveAndCommit):
+        (WTF::OSAllocator::commit):
+        (WTF::OSAllocator::decommit):
+
 2012-09-17  Uli Schlachter  <psychon@znc.in>
 

trunk/Source/WTF/wtf/OSAllocatorPosix.cpp

@@ -42 +42 @@
     if (result == MAP_FAILED)
         CRASH();
-#elif OS(LINUX)
-    void* result = mmap(0, bytes, PROT_NONE, MAP_NORESERVE | MAP_PRIVATE | MAP_ANON, -1, 0);
-    if (result == MAP_FAILED)
-        CRASH();
+#else // OS(QNX)
+
+    void* result = reserveAndCommit(bytes, usage, writable, executable, includesGuardPages);
+#if OS(LINUX)
     madvise(result, bytes, MADV_DONTNEED);
-#else
-    void* result = reserveAndCommit(bytes, usage, writable, executable, includesGuardPages);
-#if HAVE(MADV_FREE_REUSE)
+#elif HAVE(MADV_FREE_REUSE)
     // To support the "reserve then commit" model, we have to initially decommit.
     while (madvise(result, bytes, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { }
@@ -72 +70 @@
     if (executable)
         flags |= MAP_JIT;
+#endif
+
+#if (OS(LINUX) && CPU(X86_64))
+    // Linux distros usually do not allow overcommit by default, so
+    // JSC's strategy of mmaping a large amount of memory upfront
+    // won't work very well on some systems. Fortunately there's a
+    // flag we can pass to mmap to disable the overcommit check for
+    // this particular call, so we can get away with it as long as the
+    // overcommit flag value in /proc/sys/vm/overcommit_memory is 0
+    // ('heuristic') and not 2 (always check). 0 is the usual default
+    // value, so this should work well in general.
+    flags |= MAP_NORESERVE;
 #endif
 
@@ -132 +142 @@
         CRASH();
 #elif OS(LINUX)
-    int protection = PROT_READ;
-    if (writable)
-        protection |= PROT_WRITE;
-    if (executable)
-        protection |= PROT_EXEC;
-    if (!mprotect(address, bytes, protection))
-        CRASH();
+    UNUSED_PARAM(writable);
+    UNUSED_PARAM(executable);
     madvise(address, bytes, MADV_WILLNEED);
 #elif HAVE(MADV_FREE_REUSE)
@@ -160 +165 @@
 #elif OS(LINUX)
     madvise(address, bytes, MADV_DONTNEED);
-    if (!mprotect(address, bytes, PROT_NONE))
-        CRASH();
 #elif HAVE(MADV_FREE_REUSE)
     while (madvise(address, bytes, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { }