65502 2011-08-01 17:44:38 -0700 Virtual copying of FastMalloc allocated memory causes madvise MADV_FREE_REUSABLE errors 2011-08-02 14:19:21 -0700 1 1 1 Unclassified WebKit WebCore Misc. 528+ (Nightly build) Mac All RESOLVED FIXED InRadar P2 Normal --- 1 msaboff msaboff psolanki oldest_to_newest 445036 0 msaboff 2011-08-01 17:44:38 -0700 There are two instances where we make virtual copies of memory allocated via FastMalloc. One is when we use vm_copy in PurgeableBuffer::create() and the other is implicit in CoreIPC where we use the MACH_MSG_VIRTUAL_COPY flag in Connection::sendOutgoingMessage. In both cases, the kernel creates a second reference to the region being copied. These additional references preclude using the MADV_FREE_REUSABLE flag in madvise. This stops us from making memory available to the system for other processes. 445047 1 102602 msaboff 2011-08-01 17:54:45 -0700 Created attachment 102602 Proposed patch 445053 2 msaboff 2011-08-01 18:03:40 -0700 Two defects in Radar: <rdar://problem/9747241> and <rdar://problem/9747279>. 445065 3 102602 darin 2011-08-01 18:19:55 -0700 Comment on attachment 102602 Proposed patch View in context: https://bugs.webkit.org/attachment.cgi?id=102602&action=review > Source/WebCore/platform/mac/PurgeableBufferMac.cpp:67 > + memcpy(reinterpret_cast<char*>(buffer), data, size); Since memcpy’s destination is a void* I would not expect you’d need to typecast a pointer to use it as a memcpy destination. Can you just pass buffer without a typecast? 445488 4 msaboff 2011-08-02 13:27:04 -0700 (In reply to comment #3) > (From update of attachment 102602 [details]) > View in context: https://bugs.webkit.org/attachment.cgi?id=102602&action=review > > > Source/WebCore/platform/mac/PurgeableBufferMac.cpp:67 > > + memcpy(reinterpret_cast<char*>(buffer), data, size); > > Since memcpy’s destination is a void* I would not expect you’d need to typecast a pointer to use it as a memcpy destination. Can you just pass buffer without a typecast? The cast is needed because vm_address_t is really a uintptr_t which is an unsigned long, a non-pointer type. 445527 5 msaboff 2011-08-02 14:19:21 -0700 Committed r92231: <http://trac.webkit.org/changeset/92231> 102602 2011-08-01 17:54:45 -0700 2011-08-01 18:19:55 -0700 Proposed patch 65502.patch text/plain 5237 msaboff SW5kZXg6IFNvdXJjZS9KYXZhU2NyaXB0Q29yZS9DaGFuZ2VMb2cKPT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PQotLS0gU291 cmNlL0phdmFTY3JpcHRDb3JlL0NoYW5nZUxvZwkocmV2aXNpb24gOTIxNTUpCisrKyBTb3VyY2Uv SmF2YVNjcmlwdENvcmUvQ2hhbmdlTG9nCSh3b3JraW5nIGNvcHkpCkBAIC0xLDMgKzEsMTYgQEAK KzIwMTEtMDgtMDEgIE1pY2hhZWwgU2Fib2ZmICA8bXNhYm9mZkBhcHBsZS5jb20+CisKKyAgICAg ICAgVmlydHVhbCBjb3B5aW5nIG9mIEZhc3RNYWxsb2MgYWxsb2NhdGVkIG1lbW9yeSBjYXVzZXMg bWFkdmlzZSBNQURWX0ZSRUVfUkVVU0FCTEUgZXJyb3JzCisgICAgICAgIGh0dHBzOi8vYnVncy53 ZWJraXQub3JnL3Nob3dfYnVnLmNnaT9pZD02NTUwMgorCisgICAgICAgIFJldmlld2VkIGJ5IE5P 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