--- a/src/hotspot/os/linux/os_linux.cpp Tue Mar 06 17:15:16 2018 -0500
+++ b/src/hotspot/os/linux/os_linux.cpp Tue Mar 06 17:45:31 2018 -0500
@@ -3053,12 +3053,10 @@
return res != (uintptr_t) MAP_FAILED;
}
-// If there is no page mapped/committed, top (bottom + size) is returned
-static address get_stack_mapped_bottom(address bottom,
- size_t size,
- bool committed_only /* must have backing pages */) {
- // address used to test if the page is mapped/committed
- address test_addr = bottom + size;
+static address get_stack_commited_bottom(address bottom, size_t size) {
+ address nbot = bottom;
+ address ntop = bottom + size;
+
size_t page_sz = os::vm_page_size();
unsigned pages = size / page_sz;
@@ -3070,39 +3068,38 @@
while (imin < imax) {
imid = (imax + imin) / 2;
- test_addr = bottom + (imid * page_sz);
+ nbot = ntop - (imid * page_sz);
// Use a trick with mincore to check whether the page is mapped or not.
// mincore sets vec to 1 if page resides in memory and to 0 if page
// is swapped output but if page we are asking for is unmapped
// it returns -1,ENOMEM
- mincore_return_value = mincore(test_addr, page_sz, vec);
-
- if (mincore_return_value == -1 || (committed_only && (vec[0] & 0x01) == 0)) {
- // Page is not mapped/committed go up
- // to find first mapped/committed page
- if ((mincore_return_value == -1 && errno != EAGAIN)
- || (committed_only && (vec[0] & 0x01) == 0)) {
- assert(mincore_return_value != -1 || errno == ENOMEM, "Unexpected mincore errno");
-
- imin = imid + 1;
+ mincore_return_value = mincore(nbot, page_sz, vec);
+
+ if (mincore_return_value == -1) {
+ // Page is not mapped go up
+ // to find first mapped page
+ if (errno != EAGAIN) {
+ assert(errno == ENOMEM, "Unexpected mincore errno");
+ imax = imid;
}
} else {
- // mapped/committed, go down
- imax= imid;
+ // Page is mapped go down
+ // to find first not mapped page
+ imin = imid + 1;
}
}
- // Adjust stack bottom one page up if last checked page is not mapped/committed
- if (mincore_return_value == -1 || (committed_only && (vec[0] & 0x01) == 0)) {
- assert(mincore_return_value != -1 || (errno != EAGAIN && errno != ENOMEM),
- "Should not get to here");
-
- test_addr = test_addr + page_sz;
- }
-
- return test_addr;
-}
+ nbot = nbot + page_sz;
+
+ // Adjust stack bottom one page up if last checked page is not mapped
+ if (mincore_return_value == -1) {
+ nbot = nbot + page_sz;
+ }
+
+ return nbot;
+}
+
// Linux uses a growable mapping for the stack, and if the mapping for
// the stack guard pages is not removed when we detach a thread the
@@ -3140,9 +3137,9 @@
if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) {
// Fallback to slow path on all errors, including EAGAIN
- stack_extent = (uintptr_t) get_stack_mapped_bottom(os::Linux::initial_thread_stack_bottom(),
- (size_t)addr - stack_extent,
- false /* committed_only */);
+ stack_extent = (uintptr_t) get_stack_commited_bottom(
+ os::Linux::initial_thread_stack_bottom(),
+ (size_t)addr - stack_extent);
}
if (stack_extent < (uintptr_t)addr) {
@@ -3169,11 +3166,6 @@
return os::uncommit_memory(addr, size);
}
-size_t os::committed_stack_size(address bottom, size_t size) {
- address bot = get_stack_mapped_bottom(bottom, size, true /* committed_only */);
- return size_t(bottom + size - bot);
-}
-
// If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
// at 'requested_addr'. If there are existing memory mappings at the same
// location, however, they will be overwritten. If 'fixed' is false,