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src/os/linux/vm/os_linux.cpp
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@@ -925,33 +925,34 @@
return false;
}
// Locate initial thread stack. This special handling of initial thread stack
// is needed because pthread_getattr_np() on most (all?) Linux distros returns
-// bogus value for initial thread.
+// bogus value for the primordial process thread. While the launcher has created
+// the VM in a new thread since JDK 6, we still have to allow for the use of the
+// JNI invocation API from a primordial thread.
void os::Linux::capture_initial_stack(size_t max_size) {
- // stack size is the easy part, get it from RLIMIT_STACK
+
+ // max_size is either 0 (which means accept OS default for thread stacks) or
+ // a user-specified value known to be greater than the minimum needed. If we
+ // are actually on the primordial thread we can make it appear that we have a
+ // smaller max_size stack by inserting the guard pages at that location. But we
+ // can not do anything to emulate a larger stack than what has been provided by
+ // the OS or threading library. In fact if we try to use a stack greater than
+ // what is set by rlimit then we will crash the hosting process.
+
+ // Mamimum stack size is the easy part, get it from RLIMIT_STACK
+ // If this is "unlimited" then it will be a huge value.
struct rlimit rlim;
getrlimit(RLIMIT_STACK, &rlim);
size_t stack_size = rlim.rlim_cur;
// 6308388: a bug in ld.so will relocate its own .data section to the
// lower end of primordial stack; reduce ulimit -s value a little bit
// so we won't install guard page on ld.so's data section.
stack_size -= 2 * page_size();
- // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
- // 7.1, in both cases we will get 2G in return value.
- // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
- // SuSE 7.2, Debian) can not handle alternate signal stack correctly
- // for initial thread if its stack size exceeds 6M. Cap it at 2M,
- // in case other parts in glibc still assumes 2M max stack size.
- // FIXME: alt signal stack is gone, maybe we can relax this constraint?
- // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
- if (stack_size > 2 * K * K IA64_ONLY(*2)) {
- stack_size = 2 * K * K IA64_ONLY(*2);
- }
// Try to figure out where the stack base (top) is. This is harder.
//
// When an application is started, glibc saves the initial stack pointer in
// a global variable "__libc_stack_end", which is then used by system
// libraries. __libc_stack_end should be pretty close to stack top. The
@@ -1107,11 +1108,12 @@
}
// stack_top could be partially down the page so align it
stack_top = align_size_up(stack_top, page_size());
- if (max_size && stack_size > max_size) {
+ // Allowed stack value is minimum of max_size and what we derived from rlimit
+ if (max_size > 0 && stack_size > max_size) {
_initial_thread_stack_size = max_size;
} else {
_initial_thread_stack_size = stack_size;
}
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