From f804a7e9f9ba6f5dac4fc2f10b464f98cd319874 Mon Sep 17 00:00:00 2001 From: Xiaobin Lu Date: Tue, 5 Feb 2008 23:21:57 -0800 Subject: [PATCH] 6610420: Debug VM crashes during monitor lock rank checking Make SerializePage lock as raw lock and add name for mutex locks Reviewed-by: never, dice, dholmes --- hotspot/src/share/vm/runtime/mutex.cpp | 13 ++++++++---- hotspot/src/share/vm/runtime/mutex.hpp | 8 ++++--- hotspot/src/share/vm/runtime/mutexLocker.cpp | 4 ---- hotspot/src/share/vm/runtime/mutexLocker.hpp | 1 - hotspot/src/share/vm/runtime/os.cpp | 22 +++++++++----------- 5 files changed, 24 insertions(+), 24 deletions(-) diff --git a/hotspot/src/share/vm/runtime/mutex.cpp b/hotspot/src/share/vm/runtime/mutex.cpp index a4d341b9637..c8751c2121c 100644 --- a/hotspot/src/share/vm/runtime/mutex.cpp +++ b/hotspot/src/share/vm/runtime/mutex.cpp @@ -1119,10 +1119,15 @@ Monitor::~Monitor() { assert ((UNS(_owner)|UNS(_LockWord.FullWord)|UNS(_EntryList)|UNS(_WaitSet)|UNS(_OnDeck)) == 0, "") ; } -void Monitor::ClearMonitor (Monitor * m) { +void Monitor::ClearMonitor (Monitor * m, const char *name) { m->_owner = NULL ; m->_snuck = false ; - m->_name = "UNKNOWN" ; + if (name == NULL) { + strcpy(m->_name, "UNKNOWN") ; + } else { + strncpy(m->_name, name, MONITOR_NAME_LEN - 1); + m->_name[MONITOR_NAME_LEN - 1] = '\0'; + } m->_LockWord.FullWord = 0 ; m->_EntryList = NULL ; m->_OnDeck = NULL ; @@ -1133,7 +1138,7 @@ void Monitor::ClearMonitor (Monitor * m) { Monitor::Monitor() { ClearMonitor(this); } Monitor::Monitor (int Rank, const char * name, bool allow_vm_block) { - ClearMonitor (this) ; + ClearMonitor (this, name) ; #ifdef ASSERT _allow_vm_block = allow_vm_block; _rank = Rank ; @@ -1145,7 +1150,7 @@ Mutex::~Mutex() { } Mutex::Mutex (int Rank, const char * name, bool allow_vm_block) { - ClearMonitor ((Monitor *) this) ; + ClearMonitor ((Monitor *) this, name) ; #ifdef ASSERT _allow_vm_block = allow_vm_block; _rank = Rank ; diff --git a/hotspot/src/share/vm/runtime/mutex.hpp b/hotspot/src/share/vm/runtime/mutex.hpp index 761cebb2ba4..56988e20e79 100644 --- a/hotspot/src/share/vm/runtime/mutex.hpp +++ b/hotspot/src/share/vm/runtime/mutex.hpp @@ -82,6 +82,9 @@ class ParkEvent ; // *in that order*. If their implementations change such that these // assumptions are violated, a whole lot of code will break. +// The default length of monitor name is choosen to be 64 to avoid false sharing. +static const int MONITOR_NAME_LEN = 64; + class Monitor : public CHeapObj { public: @@ -126,9 +129,8 @@ class Monitor : public CHeapObj { volatile intptr_t _WaitLock [1] ; // Protects _WaitSet ParkEvent * volatile _WaitSet ; // LL of ParkEvents volatile bool _snuck; // Used for sneaky locking (evil). - const char * _name; // Name of mutex int NotifyCount ; // diagnostic assist - double pad [8] ; // avoid false sharing + char _name[MONITOR_NAME_LEN]; // Name of mutex // Debugging fields for naming, deadlock detection, etc. (some only used in debug mode) #ifndef PRODUCT @@ -170,7 +172,7 @@ class Monitor : public CHeapObj { int ILocked () ; protected: - static void ClearMonitor (Monitor * m) ; + static void ClearMonitor (Monitor * m, const char* name = NULL) ; Monitor() ; public: diff --git a/hotspot/src/share/vm/runtime/mutexLocker.cpp b/hotspot/src/share/vm/runtime/mutexLocker.cpp index 317e24ee535..a639519d26d 100644 --- a/hotspot/src/share/vm/runtime/mutexLocker.cpp +++ b/hotspot/src/share/vm/runtime/mutexLocker.cpp @@ -188,10 +188,6 @@ void mutex_init() { def(Safepoint_lock , Monitor, safepoint, true ); // locks SnippetCache_lock/Threads_lock - if (!UseMembar) { - def(SerializePage_lock , Monitor, leaf, true ); - } - def(Threads_lock , Monitor, barrier, true ); def(VMOperationQueue_lock , Monitor, nonleaf, true ); // VM_thread allowed to block on these diff --git a/hotspot/src/share/vm/runtime/mutexLocker.hpp b/hotspot/src/share/vm/runtime/mutexLocker.hpp index 59f145fcfb6..e21367cb960 100644 --- a/hotspot/src/share/vm/runtime/mutexLocker.hpp +++ b/hotspot/src/share/vm/runtime/mutexLocker.hpp @@ -52,7 +52,6 @@ extern Mutex* DerivedPointerTableGC_lock; // a lock to protect the derive extern Monitor* VMOperationQueue_lock; // a lock on queue of vm_operations waiting to execute extern Monitor* VMOperationRequest_lock; // a lock on Threads waiting for a vm_operation to terminate extern Monitor* Safepoint_lock; // a lock used by the safepoint abstraction -extern Monitor* SerializePage_lock; // a lock used when VMThread changing serialize memory page permission during safepoint extern Monitor* Threads_lock; // a lock on the Threads table of active Java threads // (also used by Safepoints too to block threads creation/destruction) extern Monitor* CGC_lock; // used for coordination between diff --git a/hotspot/src/share/vm/runtime/os.cpp b/hotspot/src/share/vm/runtime/os.cpp index 72dfb2265ff..980c1179340 100644 --- a/hotspot/src/share/vm/runtime/os.cpp +++ b/hotspot/src/share/vm/runtime/os.cpp @@ -956,7 +956,6 @@ bool os::set_boot_path(char fileSep, char pathSep) { return true; } - void os::set_memory_serialize_page(address page) { int count = log2_intptr(sizeof(class JavaThread)) - log2_intptr(64); _mem_serialize_page = (volatile int32_t *)page; @@ -967,6 +966,8 @@ void os::set_memory_serialize_page(address page) { set_serialize_page_mask((uintptr_t)(vm_page_size() - sizeof(int32_t))); } +static volatile intptr_t SerializePageLock = 0; + // This method is called from signal handler when SIGSEGV occurs while the current // thread tries to store to the "read-only" memory serialize page during state // transition. @@ -974,15 +975,14 @@ void os::block_on_serialize_page_trap() { if (TraceSafepoint) { tty->print_cr("Block until the serialize page permission restored"); } - // When VMThread is holding the SerializePage_lock during modifying the + // When VMThread is holding the SerializePageLock during modifying the // access permission of the memory serialize page, the following call // will block until the permission of that page is restored to rw. // Generally, it is unsafe to manipulate locks in signal handlers, but in // this case, it's OK as the signal is synchronous and we know precisely when - // it can occur. SerializePage_lock is a transiently-held leaf lock, so - // lock_without_safepoint_check should be safe. - SerializePage_lock->lock_without_safepoint_check(); - SerializePage_lock->unlock(); + // it can occur. + Thread::muxAcquire(&SerializePageLock, "set_memory_serialize_page"); + Thread::muxRelease(&SerializePageLock); } // Serialize all thread state variables @@ -990,14 +990,12 @@ void os::serialize_thread_states() { // On some platforms such as Solaris & Linux, the time duration of the page // permission restoration is observed to be much longer than expected due to // scheduler starvation problem etc. To avoid the long synchronization - // time and expensive page trap spinning, 'SerializePage_lock' is used to block - // the mutator thread if such case is encountered. Since this method is always - // called by VMThread during safepoint, lock_without_safepoint_check is used - // instead. See bug 6546278. - SerializePage_lock->lock_without_safepoint_check(); + // time and expensive page trap spinning, 'SerializePageLock' is used to block + // the mutator thread if such case is encountered. See bug 6546278 for details. + Thread::muxAcquire(&SerializePageLock, "serialize_thread_states"); os::protect_memory( (char *)os::get_memory_serialize_page(), os::vm_page_size() ); os::unguard_memory( (char *)os::get_memory_serialize_page(), os::vm_page_size() ); - SerializePage_lock->unlock(); + Thread::muxRelease(&SerializePageLock); } // Returns true if the current stack pointer is above the stack shadow