Changeset 221548 in webkit

Timestamp:

Sep 3, 2017 3:31:29 AM (7 years ago)

Author:

Yusuke Suzuki

Message:

Large virtual memory region allocation requires MMAP_NORESERVE in Linux
​https://bugs.webkit.org/show_bug.cgi?id=176211

Reviewed by Geoffrey Garen.

In Linux, we cannot allocate very large memory region without MMAP_NORESERVE.
Linux kernel needs to reserve swap area for allocated memory region. If the
swap area is exhausted, kernel fails to allocate the memory region with ENOMEM.

This patch adds MMAP_NORESERVE to mmap flags in Linux. By adding this flag,
mmap does not need to reserve swap area for the reserved memory region.
This allows us to reserve very large memory region that is necessary for Gigacage.

• bmalloc/BPlatform.h:
• bmalloc/VMAllocate.h:

(bmalloc::tryVMAllocate):

Location:

trunk/Source/bmalloc

Files:

• ChangeLog (modified) (1 diff)
• bmalloc/BPlatform.h (modified) (1 diff)
• bmalloc/VMAllocate.h (modified) (2 diffs)

trunk/Source/bmalloc/ChangeLog

@@ +1 @@
+2017-09-03  Yusuke Suzuki  <utatane.tea@gmail.com>
+
+        Large virtual memory region allocation requires MMAP_NORESERVE in Linux
+        https://bugs.webkit.org/show_bug.cgi?id=176211
+
+        Reviewed by Geoffrey Garen.
+
+        In Linux, we cannot allocate very large memory region without MMAP_NORESERVE.
+        Linux kernel needs to reserve swap area for allocated memory region. If the
+        swap area is exhausted, kernel fails to allocate the memory region with ENOMEM.
+
+        This patch adds MMAP_NORESERVE to mmap flags in Linux. By adding this flag,
+        mmap does not need to reserve swap area for the reserved memory region.
+        This allows us to reserve very large memory region that is necessary for Gigacage.
+
+        * bmalloc/BPlatform.h:
+        * bmalloc/VMAllocate.h:
+        (bmalloc::tryVMAllocate):
+
 2017-08-22  Filip Pizlo  <fpizlo@apple.com>
 

trunk/Source/bmalloc/bmalloc/BPlatform.h

@@ -43 +43 @@
 #endif
 
+#ifdef __linux__
+#define BOS_LINUX 1
+#endif
+
 #if defined(WIN32) || defined(_WIN32)
 #define BOS_WINDOWS 1

trunk/Source/bmalloc/bmalloc/VMAllocate.h

@@ -45 +45 @@
 #if BOS(DARWIN)
 #define BMALLOC_VM_TAG VM_MAKE_TAG(VM_MEMORY_TCMALLOC)
-#else
+#define BMALLOC_NORESERVE 0
+#elif BOS(LINUX)
 #define BMALLOC_VM_TAG -1
+#define BMALLOC_NORESERVE MAP_NORESERVE
+#else
+#define BMALLOC_VM_TAG -1
+#define BMALLOC_NORESERVE 0
 #endif
 
@@ -117 +122 @@
 {
     vmValidate(vmSize);
-    void* result = mmap(0, vmSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, BMALLOC_VM_TAG, 0);
+    void* result = mmap(0, vmSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | BMALLOC_NORESERVE, BMALLOC_VM_TAG, 0);
     if (result == MAP_FAILED) {
         logVMFailure();