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rev 6908 : 8058209: Race in G1 card scanning could allow scanning of memory covered by PLABs
Summary: Read _top before _gc_time_stamp in saved_mark_word() with LoadLoad order to ensure we get a consistent view
Reviewed-by: brutisso, dcubed, dholmes, stefank
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--- old/hotspot/src/share/vm/gc_implementation/g1/heapRegion.cpp
+++ new/hotspot/src/share/vm/gc_implementation/g1/heapRegion.cpp
1 1 /*
2 2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 4 *
5 5 * This code is free software; you can redistribute it and/or modify it
6 6 * under the terms of the GNU General Public License version 2 only, as
7 7 * published by the Free Software Foundation.
8 8 *
9 9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 12 * version 2 for more details (a copy is included in the LICENSE file that
13 13 * accompanied this code).
14 14 *
15 15 * You should have received a copy of the GNU General Public License version
16 16 * 2 along with this work; if not, write to the Free Software Foundation,
17 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 18 *
19 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 20 * or visit www.oracle.com if you need additional information or have any
21 21 * questions.
22 22 *
23 23 */
24 24
25 25 #include "precompiled.hpp"
26 26 #include "code/nmethod.hpp"
27 27 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
28 28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
29 29 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
30 30 #include "gc_implementation/g1/heapRegion.inline.hpp"
31 31 #include "gc_implementation/g1/heapRegionBounds.inline.hpp"
32 32 #include "gc_implementation/g1/heapRegionRemSet.hpp"
33 33 #include "gc_implementation/g1/heapRegionManager.inline.hpp"
34 34 #include "gc_implementation/shared/liveRange.hpp"
35 35 #include "memory/genOopClosures.inline.hpp"
36 36 #include "memory/iterator.hpp"
37 37 #include "memory/space.inline.hpp"
38 38 #include "oops/oop.inline.hpp"
39 39 #include "runtime/orderAccess.inline.hpp"
40 40
41 41 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
42 42
43 43 int HeapRegion::LogOfHRGrainBytes = 0;
44 44 int HeapRegion::LogOfHRGrainWords = 0;
45 45 size_t HeapRegion::GrainBytes = 0;
46 46 size_t HeapRegion::GrainWords = 0;
47 47 size_t HeapRegion::CardsPerRegion = 0;
48 48
49 49 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
50 50 HeapRegion* hr, ExtendedOopClosure* cl,
51 51 CardTableModRefBS::PrecisionStyle precision,
52 52 FilterKind fk) :
53 53 DirtyCardToOopClosure(hr, cl, precision, NULL),
54 54 _hr(hr), _fk(fk), _g1(g1) { }
55 55
56 56 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
57 57 OopClosure* oc) :
58 58 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
59 59
60 60 template<class ClosureType>
61 61 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
62 62 HeapRegion* hr,
63 63 HeapWord* cur, HeapWord* top) {
64 64 oop cur_oop = oop(cur);
65 65 size_t oop_size = hr->block_size(cur);
66 66 HeapWord* next_obj = cur + oop_size;
67 67 while (next_obj < top) {
68 68 // Keep filtering the remembered set.
69 69 if (!g1h->is_obj_dead(cur_oop, hr)) {
70 70 // Bottom lies entirely below top, so we can call the
71 71 // non-memRegion version of oop_iterate below.
72 72 cur_oop->oop_iterate(cl);
73 73 }
74 74 cur = next_obj;
75 75 cur_oop = oop(cur);
76 76 oop_size = hr->block_size(cur);
77 77 next_obj = cur + oop_size;
78 78 }
79 79 return cur;
80 80 }
81 81
82 82 void HeapRegionDCTOC::walk_mem_region(MemRegion mr,
83 83 HeapWord* bottom,
84 84 HeapWord* top) {
85 85 G1CollectedHeap* g1h = _g1;
86 86 size_t oop_size;
87 87 ExtendedOopClosure* cl2 = NULL;
88 88
89 89 FilterIntoCSClosure intoCSFilt(this, g1h, _cl);
90 90 FilterOutOfRegionClosure outOfRegionFilt(_hr, _cl);
91 91
92 92 switch (_fk) {
93 93 case NoFilterKind: cl2 = _cl; break;
94 94 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
95 95 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
96 96 default: ShouldNotReachHere();
97 97 }
98 98
99 99 // Start filtering what we add to the remembered set. If the object is
100 100 // not considered dead, either because it is marked (in the mark bitmap)
101 101 // or it was allocated after marking finished, then we add it. Otherwise
102 102 // we can safely ignore the object.
103 103 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
104 104 oop_size = oop(bottom)->oop_iterate(cl2, mr);
105 105 } else {
106 106 oop_size = _hr->block_size(bottom);
107 107 }
108 108
109 109 bottom += oop_size;
110 110
111 111 if (bottom < top) {
112 112 // We replicate the loop below for several kinds of possible filters.
113 113 switch (_fk) {
114 114 case NoFilterKind:
115 115 bottom = walk_mem_region_loop(_cl, g1h, _hr, bottom, top);
116 116 break;
117 117
118 118 case IntoCSFilterKind: {
119 119 FilterIntoCSClosure filt(this, g1h, _cl);
120 120 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
121 121 break;
122 122 }
123 123
124 124 case OutOfRegionFilterKind: {
125 125 FilterOutOfRegionClosure filt(_hr, _cl);
126 126 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
127 127 break;
128 128 }
129 129
130 130 default:
131 131 ShouldNotReachHere();
132 132 }
133 133
134 134 // Last object. Need to do dead-obj filtering here too.
135 135 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
136 136 oop(bottom)->oop_iterate(cl2, mr);
137 137 }
138 138 }
139 139 }
140 140
141 141 size_t HeapRegion::max_region_size() {
142 142 return HeapRegionBounds::max_size();
143 143 }
144 144
145 145 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
146 146 uintx region_size = G1HeapRegionSize;
147 147 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
148 148 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
149 149 region_size = MAX2(average_heap_size / HeapRegionBounds::target_number(),
150 150 (uintx) HeapRegionBounds::min_size());
151 151 }
152 152
153 153 int region_size_log = log2_long((jlong) region_size);
154 154 // Recalculate the region size to make sure it's a power of
155 155 // 2. This means that region_size is the largest power of 2 that's
156 156 // <= what we've calculated so far.
157 157 region_size = ((uintx)1 << region_size_log);
158 158
159 159 // Now make sure that we don't go over or under our limits.
160 160 if (region_size < HeapRegionBounds::min_size()) {
161 161 region_size = HeapRegionBounds::min_size();
162 162 } else if (region_size > HeapRegionBounds::max_size()) {
163 163 region_size = HeapRegionBounds::max_size();
164 164 }
165 165
166 166 // And recalculate the log.
167 167 region_size_log = log2_long((jlong) region_size);
168 168
169 169 // Now, set up the globals.
170 170 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
171 171 LogOfHRGrainBytes = region_size_log;
172 172
173 173 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
174 174 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
175 175
176 176 guarantee(GrainBytes == 0, "we should only set it once");
177 177 // The cast to int is safe, given that we've bounded region_size by
178 178 // MIN_REGION_SIZE and MAX_REGION_SIZE.
179 179 GrainBytes = (size_t)region_size;
180 180
181 181 guarantee(GrainWords == 0, "we should only set it once");
182 182 GrainWords = GrainBytes >> LogHeapWordSize;
183 183 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
184 184
185 185 guarantee(CardsPerRegion == 0, "we should only set it once");
186 186 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
187 187 }
188 188
189 189 void HeapRegion::reset_after_compaction() {
190 190 G1OffsetTableContigSpace::reset_after_compaction();
191 191 // After a compaction the mark bitmap is invalid, so we must
192 192 // treat all objects as being inside the unmarked area.
193 193 zero_marked_bytes();
194 194 init_top_at_mark_start();
195 195 }
196 196
197 197 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
198 198 assert(_humongous_start_region == NULL,
199 199 "we should have already filtered out humongous regions");
200 200 assert(_end == _orig_end,
201 201 "we should have already filtered out humongous regions");
202 202
203 203 _in_collection_set = false;
204 204
205 205 set_allocation_context(AllocationContext::system());
206 206 set_young_index_in_cset(-1);
207 207 uninstall_surv_rate_group();
208 208 set_free();
209 209 reset_pre_dummy_top();
210 210
211 211 if (!par) {
212 212 // If this is parallel, this will be done later.
213 213 HeapRegionRemSet* hrrs = rem_set();
214 214 if (locked) {
215 215 hrrs->clear_locked();
216 216 } else {
217 217 hrrs->clear();
218 218 }
219 219 _claimed = InitialClaimValue;
220 220 }
221 221 zero_marked_bytes();
222 222
223 223 _offsets.resize(HeapRegion::GrainWords);
224 224 init_top_at_mark_start();
225 225 if (clear_space) clear(SpaceDecorator::Mangle);
226 226 }
227 227
228 228 void HeapRegion::par_clear() {
229 229 assert(used() == 0, "the region should have been already cleared");
230 230 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
231 231 HeapRegionRemSet* hrrs = rem_set();
232 232 hrrs->clear();
233 233 CardTableModRefBS* ct_bs =
234 234 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
235 235 ct_bs->clear(MemRegion(bottom(), end()));
236 236 }
237 237
238 238 void HeapRegion::calc_gc_efficiency() {
239 239 // GC efficiency is the ratio of how much space would be
240 240 // reclaimed over how long we predict it would take to reclaim it.
241 241 G1CollectedHeap* g1h = G1CollectedHeap::heap();
242 242 G1CollectorPolicy* g1p = g1h->g1_policy();
243 243
244 244 // Retrieve a prediction of the elapsed time for this region for
245 245 // a mixed gc because the region will only be evacuated during a
246 246 // mixed gc.
247 247 double region_elapsed_time_ms =
248 248 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
249 249 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
250 250 }
251 251
252 252 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
253 253 assert(!isHumongous(), "sanity / pre-condition");
254 254 assert(end() == _orig_end,
255 255 "Should be normal before the humongous object allocation");
256 256 assert(top() == bottom(), "should be empty");
257 257 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
258 258
259 259 _type.set_starts_humongous();
260 260 _humongous_start_region = this;
261 261
262 262 set_end(new_end);
263 263 _offsets.set_for_starts_humongous(new_top);
264 264 }
265 265
266 266 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
267 267 assert(!isHumongous(), "sanity / pre-condition");
268 268 assert(end() == _orig_end,
269 269 "Should be normal before the humongous object allocation");
270 270 assert(top() == bottom(), "should be empty");
271 271 assert(first_hr->startsHumongous(), "pre-condition");
272 272
273 273 _type.set_continues_humongous();
274 274 _humongous_start_region = first_hr;
275 275 }
276 276
277 277 void HeapRegion::clear_humongous() {
278 278 assert(isHumongous(), "pre-condition");
279 279
280 280 if (startsHumongous()) {
281 281 assert(top() <= end(), "pre-condition");
282 282 set_end(_orig_end);
283 283 if (top() > end()) {
284 284 // at least one "continues humongous" region after it
285 285 set_top(end());
286 286 }
287 287 } else {
288 288 // continues humongous
289 289 assert(end() == _orig_end, "sanity");
290 290 }
291 291
292 292 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
293 293 _humongous_start_region = NULL;
294 294 }
295 295
296 296 bool HeapRegion::claimHeapRegion(jint claimValue) {
297 297 jint current = _claimed;
298 298 if (current != claimValue) {
299 299 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
300 300 if (res == current) {
301 301 return true;
302 302 }
303 303 }
304 304 return false;
305 305 }
306 306
307 307 HeapRegion::HeapRegion(uint hrm_index,
308 308 G1BlockOffsetSharedArray* sharedOffsetArray,
309 309 MemRegion mr) :
310 310 G1OffsetTableContigSpace(sharedOffsetArray, mr),
311 311 _hrm_index(hrm_index),
312 312 _allocation_context(AllocationContext::system()),
313 313 _humongous_start_region(NULL),
314 314 _in_collection_set(false),
315 315 _next_in_special_set(NULL), _orig_end(NULL),
316 316 _claimed(InitialClaimValue), _evacuation_failed(false),
317 317 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
318 318 _next_young_region(NULL),
319 319 _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),
320 320 #ifdef ASSERT
321 321 _containing_set(NULL),
322 322 #endif // ASSERT
323 323 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
324 324 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
325 325 _predicted_bytes_to_copy(0)
326 326 {
327 327 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
328 328 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
329 329
330 330 initialize(mr);
331 331 }
332 332
333 333 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
334 334 assert(_rem_set->is_empty(), "Remembered set must be empty");
335 335
336 336 G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);
337 337
338 338 _orig_end = mr.end();
339 339 hr_clear(false /*par*/, false /*clear_space*/);
340 340 set_top(bottom());
341 341 record_top_and_timestamp();
342 342 }
343 343
344 344 CompactibleSpace* HeapRegion::next_compaction_space() const {
345 345 return G1CollectedHeap::heap()->next_compaction_region(this);
346 346 }
347 347
348 348 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
349 349 bool during_conc_mark) {
350 350 // We always recreate the prev marking info and we'll explicitly
351 351 // mark all objects we find to be self-forwarded on the prev
352 352 // bitmap. So all objects need to be below PTAMS.
353 353 _prev_marked_bytes = 0;
354 354
355 355 if (during_initial_mark) {
356 356 // During initial-mark, we'll also explicitly mark all objects
357 357 // we find to be self-forwarded on the next bitmap. So all
358 358 // objects need to be below NTAMS.
359 359 _next_top_at_mark_start = top();
360 360 _next_marked_bytes = 0;
361 361 } else if (during_conc_mark) {
362 362 // During concurrent mark, all objects in the CSet (including
363 363 // the ones we find to be self-forwarded) are implicitly live.
364 364 // So all objects need to be above NTAMS.
365 365 _next_top_at_mark_start = bottom();
366 366 _next_marked_bytes = 0;
367 367 }
368 368 }
369 369
370 370 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
371 371 bool during_conc_mark,
372 372 size_t marked_bytes) {
373 373 assert(0 <= marked_bytes && marked_bytes <= used(),
374 374 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
375 375 marked_bytes, used()));
376 376 _prev_top_at_mark_start = top();
377 377 _prev_marked_bytes = marked_bytes;
378 378 }
379 379
380 380 HeapWord*
381 381 HeapRegion::object_iterate_mem_careful(MemRegion mr,
382 382 ObjectClosure* cl) {
383 383 G1CollectedHeap* g1h = G1CollectedHeap::heap();
384 384 // We used to use "block_start_careful" here. But we're actually happy
385 385 // to update the BOT while we do this...
386 386 HeapWord* cur = block_start(mr.start());
387 387 mr = mr.intersection(used_region());
388 388 if (mr.is_empty()) return NULL;
389 389 // Otherwise, find the obj that extends onto mr.start().
390 390
391 391 assert(cur <= mr.start()
392 392 && (oop(cur)->klass_or_null() == NULL ||
393 393 cur + oop(cur)->size() > mr.start()),
394 394 "postcondition of block_start");
395 395 oop obj;
396 396 while (cur < mr.end()) {
397 397 obj = oop(cur);
398 398 if (obj->klass_or_null() == NULL) {
399 399 // Ran into an unparseable point.
400 400 return cur;
401 401 } else if (!g1h->is_obj_dead(obj)) {
402 402 cl->do_object(obj);
403 403 }
404 404 if (cl->abort()) return cur;
405 405 // The check above must occur before the operation below, since an
406 406 // abort might invalidate the "size" operation.
407 407 cur += block_size(cur);
408 408 }
409 409 return NULL;
410 410 }
411 411
412 412 HeapWord*
413 413 HeapRegion::
414 414 oops_on_card_seq_iterate_careful(MemRegion mr,
415 415 FilterOutOfRegionClosure* cl,
416 416 bool filter_young,
417 417 jbyte* card_ptr) {
418 418 // Currently, we should only have to clean the card if filter_young
419 419 // is true and vice versa.
420 420 if (filter_young) {
421 421 assert(card_ptr != NULL, "pre-condition");
422 422 } else {
423 423 assert(card_ptr == NULL, "pre-condition");
424 424 }
425 425 G1CollectedHeap* g1h = G1CollectedHeap::heap();
426 426
427 427 // If we're within a stop-world GC, then we might look at a card in a
428 428 // GC alloc region that extends onto a GC LAB, which may not be
429 429 // parseable. Stop such at the "saved_mark" of the region.
430 430 if (g1h->is_gc_active()) {
431 431 mr = mr.intersection(used_region_at_save_marks());
432 432 } else {
433 433 mr = mr.intersection(used_region());
434 434 }
435 435 if (mr.is_empty()) return NULL;
436 436 // Otherwise, find the obj that extends onto mr.start().
437 437
438 438 // The intersection of the incoming mr (for the card) and the
439 439 // allocated part of the region is non-empty. This implies that
440 440 // we have actually allocated into this region. The code in
441 441 // G1CollectedHeap.cpp that allocates a new region sets the
442 442 // is_young tag on the region before allocating. Thus we
443 443 // safely know if this region is young.
444 444 if (is_young() && filter_young) {
445 445 return NULL;
446 446 }
447 447
448 448 assert(!is_young(), "check value of filter_young");
449 449
450 450 // We can only clean the card here, after we make the decision that
451 451 // the card is not young. And we only clean the card if we have been
452 452 // asked to (i.e., card_ptr != NULL).
453 453 if (card_ptr != NULL) {
454 454 *card_ptr = CardTableModRefBS::clean_card_val();
455 455 // We must complete this write before we do any of the reads below.
456 456 OrderAccess::storeload();
457 457 }
458 458
459 459 // Cache the boundaries of the memory region in some const locals
460 460 HeapWord* const start = mr.start();
461 461 HeapWord* const end = mr.end();
462 462
463 463 // We used to use "block_start_careful" here. But we're actually happy
464 464 // to update the BOT while we do this...
465 465 HeapWord* cur = block_start(start);
466 466 assert(cur <= start, "Postcondition");
467 467
468 468 oop obj;
469 469
470 470 HeapWord* next = cur;
471 471 while (next <= start) {
472 472 cur = next;
473 473 obj = oop(cur);
474 474 if (obj->klass_or_null() == NULL) {
475 475 // Ran into an unparseable point.
476 476 return cur;
477 477 }
478 478 // Otherwise...
479 479 next = cur + block_size(cur);
480 480 }
481 481
482 482 // If we finish the above loop...We have a parseable object that
483 483 // begins on or before the start of the memory region, and ends
484 484 // inside or spans the entire region.
485 485
486 486 assert(obj == oop(cur), "sanity");
487 487 assert(cur <= start, "Loop postcondition");
488 488 assert(obj->klass_or_null() != NULL, "Loop postcondition");
489 489 assert((cur + block_size(cur)) > start, "Loop postcondition");
490 490
491 491 if (!g1h->is_obj_dead(obj)) {
492 492 obj->oop_iterate(cl, mr);
493 493 }
494 494
495 495 while (cur < end) {
496 496 obj = oop(cur);
497 497 if (obj->klass_or_null() == NULL) {
498 498 // Ran into an unparseable point.
499 499 return cur;
500 500 };
501 501
502 502 // Otherwise:
503 503 next = cur + block_size(cur);
504 504
505 505 if (!g1h->is_obj_dead(obj)) {
506 506 if (next < end || !obj->is_objArray()) {
507 507 // This object either does not span the MemRegion
508 508 // boundary, or if it does it's not an array.
509 509 // Apply closure to whole object.
510 510 obj->oop_iterate(cl);
511 511 } else {
512 512 // This obj is an array that spans the boundary.
513 513 // Stop at the boundary.
514 514 obj->oop_iterate(cl, mr);
515 515 }
516 516 }
517 517 cur = next;
518 518 }
519 519 return NULL;
520 520 }
521 521
522 522 // Code roots support
523 523
524 524 void HeapRegion::add_strong_code_root(nmethod* nm) {
525 525 HeapRegionRemSet* hrrs = rem_set();
526 526 hrrs->add_strong_code_root(nm);
527 527 }
528 528
529 529 void HeapRegion::add_strong_code_root_locked(nmethod* nm) {
530 530 assert_locked_or_safepoint(CodeCache_lock);
531 531 HeapRegionRemSet* hrrs = rem_set();
532 532 hrrs->add_strong_code_root_locked(nm);
533 533 }
534 534
535 535 void HeapRegion::remove_strong_code_root(nmethod* nm) {
536 536 HeapRegionRemSet* hrrs = rem_set();
537 537 hrrs->remove_strong_code_root(nm);
538 538 }
539 539
540 540 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
541 541 HeapRegionRemSet* hrrs = rem_set();
542 542 hrrs->strong_code_roots_do(blk);
543 543 }
544 544
545 545 class VerifyStrongCodeRootOopClosure: public OopClosure {
546 546 const HeapRegion* _hr;
547 547 nmethod* _nm;
548 548 bool _failures;
549 549 bool _has_oops_in_region;
550 550
551 551 template <class T> void do_oop_work(T* p) {
552 552 T heap_oop = oopDesc::load_heap_oop(p);
553 553 if (!oopDesc::is_null(heap_oop)) {
554 554 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
555 555
556 556 // Note: not all the oops embedded in the nmethod are in the
557 557 // current region. We only look at those which are.
558 558 if (_hr->is_in(obj)) {
559 559 // Object is in the region. Check that its less than top
560 560 if (_hr->top() <= (HeapWord*)obj) {
561 561 // Object is above top
562 562 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
563 563 "["PTR_FORMAT", "PTR_FORMAT") is above "
564 564 "top "PTR_FORMAT,
565 565 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
566 566 _failures = true;
567 567 return;
568 568 }
569 569 // Nmethod has at least one oop in the current region
570 570 _has_oops_in_region = true;
571 571 }
572 572 }
573 573 }
574 574
575 575 public:
576 576 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
577 577 _hr(hr), _failures(false), _has_oops_in_region(false) {}
578 578
579 579 void do_oop(narrowOop* p) { do_oop_work(p); }
580 580 void do_oop(oop* p) { do_oop_work(p); }
581 581
582 582 bool failures() { return _failures; }
583 583 bool has_oops_in_region() { return _has_oops_in_region; }
584 584 };
585 585
586 586 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
587 587 const HeapRegion* _hr;
588 588 bool _failures;
589 589 public:
590 590 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
591 591 _hr(hr), _failures(false) {}
592 592
593 593 void do_code_blob(CodeBlob* cb) {
594 594 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
595 595 if (nm != NULL) {
596 596 // Verify that the nemthod is live
597 597 if (!nm->is_alive()) {
598 598 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
599 599 PTR_FORMAT" in its strong code roots",
600 600 _hr->bottom(), _hr->end(), nm);
601 601 _failures = true;
602 602 } else {
603 603 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
604 604 nm->oops_do(&oop_cl);
605 605 if (!oop_cl.has_oops_in_region()) {
606 606 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
607 607 PTR_FORMAT" in its strong code roots "
608 608 "with no pointers into region",
609 609 _hr->bottom(), _hr->end(), nm);
610 610 _failures = true;
611 611 } else if (oop_cl.failures()) {
612 612 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
613 613 "failures for nmethod "PTR_FORMAT,
614 614 _hr->bottom(), _hr->end(), nm);
615 615 _failures = true;
616 616 }
617 617 }
618 618 }
619 619 }
620 620
621 621 bool failures() { return _failures; }
622 622 };
623 623
624 624 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
625 625 if (!G1VerifyHeapRegionCodeRoots) {
626 626 // We're not verifying code roots.
627 627 return;
628 628 }
629 629 if (vo == VerifyOption_G1UseMarkWord) {
630 630 // Marking verification during a full GC is performed after class
631 631 // unloading, code cache unloading, etc so the strong code roots
632 632 // attached to each heap region are in an inconsistent state. They won't
633 633 // be consistent until the strong code roots are rebuilt after the
634 634 // actual GC. Skip verifying the strong code roots in this particular
635 635 // time.
636 636 assert(VerifyDuringGC, "only way to get here");
637 637 return;
638 638 }
639 639
640 640 HeapRegionRemSet* hrrs = rem_set();
641 641 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
642 642
643 643 // if this region is empty then there should be no entries
644 644 // on its strong code root list
645 645 if (is_empty()) {
646 646 if (strong_code_roots_length > 0) {
647 647 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
648 648 "but has "SIZE_FORMAT" code root entries",
649 649 bottom(), end(), strong_code_roots_length);
650 650 *failures = true;
651 651 }
652 652 return;
653 653 }
654 654
655 655 if (continuesHumongous()) {
656 656 if (strong_code_roots_length > 0) {
657 657 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
658 658 "region but has "SIZE_FORMAT" code root entries",
659 659 HR_FORMAT_PARAMS(this), strong_code_roots_length);
660 660 *failures = true;
661 661 }
662 662 return;
663 663 }
664 664
665 665 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
666 666 strong_code_roots_do(&cb_cl);
667 667
668 668 if (cb_cl.failures()) {
669 669 *failures = true;
670 670 }
671 671 }
672 672
673 673 void HeapRegion::print() const { print_on(gclog_or_tty); }
674 674 void HeapRegion::print_on(outputStream* st) const {
675 675 st->print("AC%4u", allocation_context());
676 676 st->print(" %2s", get_short_type_str());
677 677 if (in_collection_set())
678 678 st->print(" CS");
679 679 else
680 680 st->print(" ");
681 681 st->print(" TS %5d", _gc_time_stamp);
682 682 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
683 683 prev_top_at_mark_start(), next_top_at_mark_start());
684 684 G1OffsetTableContigSpace::print_on(st);
685 685 }
686 686
687 687 class VerifyLiveClosure: public OopClosure {
688 688 private:
689 689 G1CollectedHeap* _g1h;
690 690 CardTableModRefBS* _bs;
691 691 oop _containing_obj;
692 692 bool _failures;
693 693 int _n_failures;
694 694 VerifyOption _vo;
695 695 public:
696 696 // _vo == UsePrevMarking -> use "prev" marking information,
697 697 // _vo == UseNextMarking -> use "next" marking information,
698 698 // _vo == UseMarkWord -> use mark word from object header.
699 699 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
700 700 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
701 701 _failures(false), _n_failures(0), _vo(vo)
702 702 {
703 703 BarrierSet* bs = _g1h->barrier_set();
704 704 if (bs->is_a(BarrierSet::CardTableModRef))
705 705 _bs = (CardTableModRefBS*)bs;
706 706 }
707 707
708 708 void set_containing_obj(oop obj) {
709 709 _containing_obj = obj;
710 710 }
711 711
712 712 bool failures() { return _failures; }
713 713 int n_failures() { return _n_failures; }
714 714
715 715 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
716 716 virtual void do_oop( oop* p) { do_oop_work(p); }
717 717
718 718 void print_object(outputStream* out, oop obj) {
719 719 #ifdef PRODUCT
720 720 Klass* k = obj->klass();
721 721 const char* class_name = InstanceKlass::cast(k)->external_name();
722 722 out->print_cr("class name %s", class_name);
723 723 #else // PRODUCT
724 724 obj->print_on(out);
725 725 #endif // PRODUCT
726 726 }
727 727
728 728 template <class T>
729 729 void do_oop_work(T* p) {
730 730 assert(_containing_obj != NULL, "Precondition");
731 731 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
732 732 "Precondition");
733 733 T heap_oop = oopDesc::load_heap_oop(p);
734 734 if (!oopDesc::is_null(heap_oop)) {
735 735 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
736 736 bool failed = false;
737 737 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
738 738 MutexLockerEx x(ParGCRareEvent_lock,
739 739 Mutex::_no_safepoint_check_flag);
740 740
741 741 if (!_failures) {
742 742 gclog_or_tty->cr();
743 743 gclog_or_tty->print_cr("----------");
744 744 }
745 745 if (!_g1h->is_in_closed_subset(obj)) {
746 746 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
747 747 gclog_or_tty->print_cr("Field "PTR_FORMAT
748 748 " of live obj "PTR_FORMAT" in region "
749 749 "["PTR_FORMAT", "PTR_FORMAT")",
750 750 p, (void*) _containing_obj,
751 751 from->bottom(), from->end());
752 752 print_object(gclog_or_tty, _containing_obj);
753 753 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
754 754 (void*) obj);
755 755 } else {
756 756 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
757 757 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
758 758 gclog_or_tty->print_cr("Field "PTR_FORMAT
759 759 " of live obj "PTR_FORMAT" in region "
760 760 "["PTR_FORMAT", "PTR_FORMAT")",
761 761 p, (void*) _containing_obj,
762 762 from->bottom(), from->end());
763 763 print_object(gclog_or_tty, _containing_obj);
764 764 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
765 765 "["PTR_FORMAT", "PTR_FORMAT")",
766 766 (void*) obj, to->bottom(), to->end());
767 767 print_object(gclog_or_tty, obj);
768 768 }
769 769 gclog_or_tty->print_cr("----------");
770 770 gclog_or_tty->flush();
771 771 _failures = true;
772 772 failed = true;
773 773 _n_failures++;
774 774 }
775 775
776 776 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
777 777 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
778 778 HeapRegion* to = _g1h->heap_region_containing(obj);
779 779 if (from != NULL && to != NULL &&
780 780 from != to &&
781 781 !to->isHumongous()) {
782 782 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
783 783 jbyte cv_field = *_bs->byte_for_const(p);
784 784 const jbyte dirty = CardTableModRefBS::dirty_card_val();
785 785
786 786 bool is_bad = !(from->is_young()
787 787 || to->rem_set()->contains_reference(p)
788 788 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
789 789 (_containing_obj->is_objArray() ?
790 790 cv_field == dirty
791 791 : cv_obj == dirty || cv_field == dirty));
792 792 if (is_bad) {
793 793 MutexLockerEx x(ParGCRareEvent_lock,
794 794 Mutex::_no_safepoint_check_flag);
795 795
796 796 if (!_failures) {
797 797 gclog_or_tty->cr();
798 798 gclog_or_tty->print_cr("----------");
799 799 }
800 800 gclog_or_tty->print_cr("Missing rem set entry:");
801 801 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
802 802 "of obj "PTR_FORMAT", "
803 803 "in region "HR_FORMAT,
804 804 p, (void*) _containing_obj,
805 805 HR_FORMAT_PARAMS(from));
806 806 _containing_obj->print_on(gclog_or_tty);
807 807 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
808 808 "in region "HR_FORMAT,
809 809 (void*) obj,
810 810 HR_FORMAT_PARAMS(to));
811 811 obj->print_on(gclog_or_tty);
812 812 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
813 813 cv_obj, cv_field);
814 814 gclog_or_tty->print_cr("----------");
815 815 gclog_or_tty->flush();
816 816 _failures = true;
817 817 if (!failed) _n_failures++;
818 818 }
819 819 }
820 820 }
821 821 }
822 822 }
823 823 };
824 824
825 825 // This really ought to be commoned up into OffsetTableContigSpace somehow.
826 826 // We would need a mechanism to make that code skip dead objects.
827 827
828 828 void HeapRegion::verify(VerifyOption vo,
829 829 bool* failures) const {
830 830 G1CollectedHeap* g1 = G1CollectedHeap::heap();
831 831 *failures = false;
832 832 HeapWord* p = bottom();
833 833 HeapWord* prev_p = NULL;
834 834 VerifyLiveClosure vl_cl(g1, vo);
835 835 bool is_humongous = isHumongous();
836 836 bool do_bot_verify = !is_young();
837 837 size_t object_num = 0;
838 838 while (p < top()) {
839 839 oop obj = oop(p);
840 840 size_t obj_size = block_size(p);
841 841 object_num += 1;
842 842
843 843 if (is_humongous != g1->isHumongous(obj_size) &&
844 844 !g1->is_obj_dead(obj, this)) { // Dead objects may have bigger block_size since they span several objects.
845 845 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
846 846 SIZE_FORMAT" words) in a %shumongous region",
847 847 p, g1->isHumongous(obj_size) ? "" : "non-",
848 848 obj_size, is_humongous ? "" : "non-");
849 849 *failures = true;
850 850 return;
851 851 }
852 852
853 853 // If it returns false, verify_for_object() will output the
854 854 // appropriate message.
855 855 if (do_bot_verify &&
856 856 !g1->is_obj_dead(obj, this) &&
857 857 !_offsets.verify_for_object(p, obj_size)) {
858 858 *failures = true;
859 859 return;
860 860 }
861 861
862 862 if (!g1->is_obj_dead_cond(obj, this, vo)) {
863 863 if (obj->is_oop()) {
864 864 Klass* klass = obj->klass();
865 865 bool is_metaspace_object = Metaspace::contains(klass) ||
866 866 (vo == VerifyOption_G1UsePrevMarking &&
867 867 ClassLoaderDataGraph::unload_list_contains(klass));
868 868 if (!is_metaspace_object) {
869 869 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
870 870 "not metadata", klass, (void *)obj);
871 871 *failures = true;
872 872 return;
873 873 } else if (!klass->is_klass()) {
874 874 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
875 875 "not a klass", klass, (void *)obj);
876 876 *failures = true;
877 877 return;
878 878 } else {
879 879 vl_cl.set_containing_obj(obj);
880 880 obj->oop_iterate_no_header(&vl_cl);
881 881 if (vl_cl.failures()) {
882 882 *failures = true;
883 883 }
884 884 if (G1MaxVerifyFailures >= 0 &&
885 885 vl_cl.n_failures() >= G1MaxVerifyFailures) {
886 886 return;
887 887 }
888 888 }
889 889 } else {
890 890 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
891 891 *failures = true;
892 892 return;
893 893 }
894 894 }
895 895 prev_p = p;
896 896 p += obj_size;
897 897 }
898 898
899 899 if (p != top()) {
900 900 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
901 901 "does not match top "PTR_FORMAT, p, top());
902 902 *failures = true;
903 903 return;
904 904 }
905 905
906 906 HeapWord* the_end = end();
907 907 assert(p == top(), "it should still hold");
908 908 // Do some extra BOT consistency checking for addresses in the
909 909 // range [top, end). BOT look-ups in this range should yield
910 910 // top. No point in doing that if top == end (there's nothing there).
911 911 if (p < the_end) {
912 912 // Look up top
913 913 HeapWord* addr_1 = p;
914 914 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
915 915 if (b_start_1 != p) {
916 916 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
917 917 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
918 918 addr_1, b_start_1, p);
919 919 *failures = true;
920 920 return;
921 921 }
922 922
923 923 // Look up top + 1
924 924 HeapWord* addr_2 = p + 1;
925 925 if (addr_2 < the_end) {
926 926 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
927 927 if (b_start_2 != p) {
928 928 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
929 929 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
930 930 addr_2, b_start_2, p);
931 931 *failures = true;
932 932 return;
933 933 }
934 934 }
935 935
936 936 // Look up an address between top and end
937 937 size_t diff = pointer_delta(the_end, p) / 2;
938 938 HeapWord* addr_3 = p + diff;
939 939 if (addr_3 < the_end) {
940 940 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
941 941 if (b_start_3 != p) {
942 942 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
943 943 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
944 944 addr_3, b_start_3, p);
945 945 *failures = true;
946 946 return;
947 947 }
948 948 }
949 949
950 950 // Loook up end - 1
951 951 HeapWord* addr_4 = the_end - 1;
952 952 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
953 953 if (b_start_4 != p) {
954 954 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
955 955 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
956 956 addr_4, b_start_4, p);
957 957 *failures = true;
958 958 return;
959 959 }
960 960 }
961 961
962 962 if (is_humongous && object_num > 1) {
963 963 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
964 964 "but has "SIZE_FORMAT", objects",
965 965 bottom(), end(), object_num);
966 966 *failures = true;
967 967 return;
968 968 }
969 969
970 970 verify_strong_code_roots(vo, failures);
971 971 }
972 972
973 973 void HeapRegion::verify() const {
974 974 bool dummy = false;
975 975 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
976 976 }
977 977
978 978 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
979 979 // away eventually.
980 980
981 981 void G1OffsetTableContigSpace::clear(bool mangle_space) {
982 982 set_top(bottom());
983 983 set_saved_mark_word(bottom());
984 984 CompactibleSpace::clear(mangle_space);
985 985 reset_bot();
986 986 }
987 987
988 988 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
989 989 Space::set_bottom(new_bottom);
990 990 _offsets.set_bottom(new_bottom);
991 991 }
992 992
993 993 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
994 994 Space::set_end(new_end);
995 995 _offsets.resize(new_end - bottom());
996 996 }
997 997
998 998 void G1OffsetTableContigSpace::print() const {
999 999 print_short();
1000 1000 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1001 1001 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1002 1002 bottom(), top(), _offsets.threshold(), end());
1003 1003 }
1004 1004
1005 1005 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1006 1006 return _offsets.initialize_threshold();
1007 1007 }
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1008 1008
1009 1009 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1010 1010 HeapWord* end) {
1011 1011 _offsets.alloc_block(start, end);
1012 1012 return _offsets.threshold();
1013 1013 }
1014 1014
1015 1015 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1016 1016 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1017 1017 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1018 - if (_gc_time_stamp < g1h->get_gc_time_stamp())
1019 - return top();
1020 - else
1018 + HeapWord* local_top = top();
1019 + OrderAccess::loadload();
1020 + if (_gc_time_stamp < g1h->get_gc_time_stamp()) {
1021 + return local_top;
1022 + } else {
1021 1023 return Space::saved_mark_word();
1024 + }
1022 1025 }
1023 1026
1024 1027 void G1OffsetTableContigSpace::record_top_and_timestamp() {
1025 1028 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1026 1029 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1027 1030
1028 1031 if (_gc_time_stamp < curr_gc_time_stamp) {
1029 1032 // The order of these is important, as another thread might be
1030 1033 // about to start scanning this region. If it does so after
1031 1034 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1032 1035 // will be false, and it will pick up top() as the high water mark
1033 1036 // of region. If it does so after _gc_time_stamp = ..., then it
1034 1037 // will pick up the right saved_mark_word() as the high water mark
1035 1038 // of the region. Either way, the behaviour will be correct.
1036 1039 Space::set_saved_mark_word(top());
1037 1040 OrderAccess::storestore();
1038 1041 _gc_time_stamp = curr_gc_time_stamp;
1039 1042 // No need to do another barrier to flush the writes above. If
1040 1043 // this is called in parallel with other threads trying to
1041 1044 // allocate into the region, the caller should call this while
1042 1045 // holding a lock and when the lock is released the writes will be
1043 1046 // flushed.
1044 1047 }
1045 1048 }
1046 1049
1047 1050 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) {
1048 1051 object_iterate(blk);
1049 1052 }
1050 1053
1051 1054 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) {
1052 1055 HeapWord* p = bottom();
1053 1056 while (p < top()) {
1054 1057 if (block_is_obj(p)) {
1055 1058 blk->do_object(oop(p));
1056 1059 }
1057 1060 p += block_size(p);
1058 1061 }
1059 1062 }
1060 1063
1061 1064 #define block_is_always_obj(q) true
1062 1065 void G1OffsetTableContigSpace::prepare_for_compaction(CompactPoint* cp) {
1063 1066 SCAN_AND_FORWARD(cp, top, block_is_always_obj, block_size);
1064 1067 }
1065 1068 #undef block_is_always_obj
1066 1069
1067 1070 G1OffsetTableContigSpace::
1068 1071 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1069 1072 MemRegion mr) :
1070 1073 _offsets(sharedOffsetArray, mr),
1071 1074 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1072 1075 _gc_time_stamp(0)
1073 1076 {
1074 1077 _offsets.set_space(this);
1075 1078 }
1076 1079
1077 1080 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
1078 1081 CompactibleSpace::initialize(mr, clear_space, mangle_space);
1079 1082 _top = bottom();
1080 1083 reset_bot();
1081 1084 }
1082 1085
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