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6952853: SIGSEGV with UseAdaptiveGCBoundary on 64b linux running jvm2008

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Shrinking of a generation and the corresponding card table was causing part of the card table to be uncommitted.

Reviewed-by: jcoomes
This commit is contained in:
Jon Masamitsu 2010-06-23 08:35:31 -07:00
parent 428d02d5d7
commit c443776640
3 changed files with 54 additions and 17 deletions
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28
hotspot/src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2001, 2008, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -566,14 +566,14 @@ void CardTableExtension::resize_covered_region_by_end(int changed_region,
#endif
// Commit new or uncommit old pages, if necessary.
resize_commit_uncommit(changed_region, new_region);
if (resize_commit_uncommit(changed_region, new_region)) {
// Set the new start of the committed region
resize_update_committed_table(changed_region, new_region);
}
// Update card table entries
resize_update_card_table_entries(changed_region, new_region);
// Set the new start of the committed region
resize_update_committed_table(changed_region, new_region);
// Update the covered region
resize_update_covered_table(changed_region, new_region);
@ -604,8 +604,9 @@ void CardTableExtension::resize_covered_region_by_end(int changed_region,
debug_only(verify_guard();)
}
void CardTableExtension::resize_commit_uncommit(int changed_region,
bool CardTableExtension::resize_commit_uncommit(int changed_region,
MemRegion new_region) {
bool result = false;
// Commit new or uncommit old pages, if necessary.
MemRegion cur_committed = _committed[changed_region];
assert(_covered[changed_region].end() == new_region.end(),
@ -675,20 +676,31 @@ void CardTableExtension::resize_commit_uncommit(int changed_region,
"card table expansion");
}
}
result = true;
} else if (new_start_aligned > cur_committed.start()) {
// Shrink the committed region
#if 0 // uncommitting space is currently unsafe because of the interactions
// of growing and shrinking regions. One region A can uncommit space
// that it owns but which is being used by another region B (maybe).
// Region B has not committed the space because it was already
// committed by region A.
MemRegion uncommit_region = committed_unique_to_self(changed_region,
MemRegion(cur_committed.start(), new_start_aligned));
if (!uncommit_region.is_empty()) {
if (!os::uncommit_memory((char*)uncommit_region.start(),
uncommit_region.byte_size())) {
vm_exit_out_of_memory(uncommit_region.byte_size(),
"card table contraction");
// If the uncommit fails, ignore it. Let the
// committed table resizing go even though the committed
// table will over state the committed space.
}
}
#else
assert(!result, "Should be false with current workaround");
#endif
}
assert(_committed[changed_region].end() == cur_committed.end(),
"end should not change");
return result;
}
void CardTableExtension::resize_update_committed_table(int changed_region,