[Barrelfish-users] [New release] free() error
Kornilios Kourtis
kornilios.kourtis at inf.ethz.ch
Mon Apr 1 17:33:54 CEST 2013
Hi Georgios,
On Sat, Mar 30, 2013 at 09:25:22PM +0000, Georgios Varisteas wrote:
> Hi,
>
> First of all some more details. I have some benchmarking programs (BOTS) with the following structure:
>
> v1 = alloc(...);
> v2 = alloc(...);
>
> do stuff...
>
> free(v1);
> free(v2);
>
> It is that second call to free that crashes. The order of the calls to
> free doesn't matter. If I remove any one of the two or both calls, all
> programs run. What is weird to me is that (having removed one of these
> calls) multiple subsequent calls to free from different parts of the
> app and not on consecutive blocks, do not cause a crash.
>
> So I did some digging and I pinpointed the error at
> ./barrelfish/slot_alloc/single_slot_alloc.c:106 due to slab_alloc()
> returning NULL. The reason for that is that the head is NULL
> (./lib/barrelfish/slab.c:91) and not the refill function which is
> constantly NULL (./lib/barrelfish/slot_alloc/single_slot_alloc.c:144).
I think I've found the bug. The slab size allocated for nodes in the ->head
list in single_slot_alloc is the number of slots divided by 2 to accommodate
for the worst case. Each node in the list maintains a range of slots so the
worst case scenario is having only odd (or even) slots in the list.
However, it seems that a possible merge of nodes was overlooked. Can you
please try the following (admittedly not tested beyond booting qemu) patch:
diff --git a/lib/barrelfish/slot_alloc/single_slot_alloc.c b/lib/barrelfish/slot_alloc/single_slot_alloc.c
index 56e4d70..9a9a61f 100644
--- a/lib/barrelfish/slot_alloc/single_slot_alloc.c
+++ b/lib/barrelfish/slot_alloc/single_slot_alloc.c
@@ -92,6 +92,15 @@ static errval_t sfree(struct slot_allocator *ca, struct capref cap)
// Freeing at the edge of walk
if (cap.slot == walk->slot + walk->space) {
walk->space++;
+
+ // check if we can merge walk to next
+ struct cnode_meta *next = walk->next;
+ if (next && next->slot == walk->slot + walk->space) {
+ walk->space += next->space;
+ walk->next = next->next;
+ slab_free(&sca->slab, next);
+ }
+
goto finish;
}
else if (cap.slot < walk->slot + walk->space) {
cheers,
Kornilios.
>
> Moreover I traced the slots (listing at the end) and although I know very little on how these mappings work, I see an overlapping between the two variables being freed which I suspect should not be there. Specifically freeing variable 1 ends with slot 292 while freeing variable 2 starts with slot 290. As I said this is a totally uneducated guess.
>
> At this point I can think plenty of workarounds but without understanding what is actually being done, I can't suggest a solution. Any more pointers?
>
>
> cheers,
> Georgios
>
>
> debug_printf(" %p %u %p %p **\n", walk->next, cap.slot, new, sca->slab.refill_func);
>
> pond20.20: ** freeing variable 1 **
> pond20.20: 0x80a8d5d8 805 0x80a8d590 0x0 **
> pond20.20: 0x80a8d5f0 807 0x80a8d590 0x0 **
> pond20.20: 0x80a8d608 809 0x80a8d590 0x0 **
> pond20.20: 0x80a8d620 811 0x80a8d590 0x0 **
> pond20.20: 0x80a8d638 813 0x80a8d590 0x0 **
> pond20.20: 0x80a8d650 815 0x80a8d590 0x0 **
> pond20.20: 0x80a8d668 817 0x80a8d590 0x0 **
> pond20.20: 0x80a8d680 819 0x80a8d590 0x0 **
> pond20.20: 0x80a8d698 821 0x80a8d590 0x0 **
> pond20.20: 0x80a8d6b0 823 0x80a8d590 0x0 **
> pond20.20: 0x80a8d6c8 825 0x80a8d590 0x0 **
> pond20.20: 0x80a8d6e0 827 0x80a8d590 0x0 **
> pond20.20: 0x80a8d6f8 829 0x80a8d590 0x0 **
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> pond20.20: 0x80a902c8 284 0x80a8f5a8 0x0 **
> pond20.20: 0x80a902e0 286 0x80a8f5a8 0x0 **
> pond20.20: 0x80a902f8 288 0x80a8f5a8 0x0 **
> pond20.20: 0x80a90310 290 0x80a8f5a8 0x0 **
> pond20.20: 0x80a90328 292 0x80a8f5a8 0x0 **
>
>
> pond20.20: ** freeing variable 2 **
> pond20.20: 0x80a8e028 290 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e040 292 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e058 294 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e070 296 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e088 298 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e0a0 300 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e0b8 302 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e0d0 304 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e0e8 306 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e100 308 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e118 310 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e130 312 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e148 314 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e160 316 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e178 318 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e190 320 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e1a8 322 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e1c0 324 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e1d8 326 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e1f0 328 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e208 330 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e220 332 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e238 334 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e250 336 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e268 338 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e280 340 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e298 342 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e2b0 344 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e2c8 346 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e2e0 348 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e2f8 350 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e310 352 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e328 354 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e340 356 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e358 358 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e370 360 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e388 362 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e3a0 364 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e3b8 366 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e3d0 368 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e3e8 370 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e400 372 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e418 374 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e430 376 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e448 378 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e460 380 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e478 382 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e490 384 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e4a8 386 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e4c0 388 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e4d8 390 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e4f0 392 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e508 394 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e520 396 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e538 398 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e550 400 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e568 402 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e580 404 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e598 406 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e5b0 408 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e5c8 410 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e5e0 412 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e5f8 414 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e610 416 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e628 418 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e640 420 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e658 422 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e670 424 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e688 426 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e6a0 428 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e6b8 430 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e6d0 432 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e6e8 434 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e700 436 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e718 438 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e730 440 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e748 442 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e760 444 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e778 446 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e790 448 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e7a8 450 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e7c0 452 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e7d8 454 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e7f0 456 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e808 458 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e820 460 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e838 462 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e850 464 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e868 466 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e880 468 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e898 470 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e8b0 472 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e8c8 474 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e8e0 476 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e8f8 478 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e910 480 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e928 482 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e940 484 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e958 486 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e970 488 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e988 490 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e9a0 492 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e9b8 494 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e9d0 496 0x80a8dff8 0x0 **
> pond20.20: 0x80a8e9e8 498 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ea00 500 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ea18 502 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ea30 504 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ea48 506 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ea60 508 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ea78 510 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ea90 512 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eaa8 514 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eac0 516 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ead8 518 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eaf0 520 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eb08 522 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eb20 524 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eb38 526 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eb50 528 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eb68 530 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eb80 532 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eb98 534 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ebb0 536 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ebc8 538 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ebe0 540 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ebf8 542 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ec10 544 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ec28 546 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ec40 548 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ec58 550 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ec70 552 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ec88 554 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eca0 556 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ecb8 558 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ecd0 560 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ece8 562 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ed00 564 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ed18 566 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ed30 568 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ed48 570 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ed60 572 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ed78 574 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ed90 576 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eda8 578 0x80a8dff8 0x0 **
> pond20.20: 0x80a8edc0 580 0x80a8dff8 0x0 **
> pond20.20: 0x80a8edd8 582 0x80a8dff8 0x0 **
> pond20.20: 0x80a8edf0 584 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ee08 586 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ee20 588 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ee38 590 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ee50 592 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ee68 594 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ee80 596 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ee98 598 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eeb0 600 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eec8 602 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eee0 604 0x80a8dff8 0x0 **
> pond20.20: 0x80a8eef8 606 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ef10 608 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ef28 610 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ef40 612 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ef58 614 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ef70 616 0x80a8dff8 0x0 **
> pond20.20: 0x80a8ef88 618 0x80a8dff8 0x0 **
> pond20.20: 0x80a8efa0 620 0x80a8dff8 0x0 **
> pond20.20: 0x80a8efb8 622 0x80a8dff8 0x0 **
> pond20.20: 0x80a8efd0 624 0x80a8dff8 0x0 **
> pond20.20: 0x80a8efe8 626 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f000 628 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f018 630 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f030 632 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f048 634 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f060 636 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f078 638 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f090 640 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f0a8 642 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f0c0 644 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f0d8 646 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f0f0 648 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f108 650 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f120 652 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f138 654 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f150 656 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f168 658 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f180 660 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f198 662 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f1b0 664 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f1c8 666 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f1e0 668 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f1f8 670 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f210 672 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f228 674 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f240 676 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f258 678 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f270 680 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f288 682 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f2a0 684 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f2b8 686 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f2d0 688 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f2e8 690 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f300 692 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f318 694 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f330 696 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f348 698 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f360 700 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f378 702 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f390 704 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f3a8 706 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f3c0 708 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f3d8 710 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f3f0 712 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f408 714 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f420 716 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f438 718 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f450 720 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f468 722 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f480 724 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f498 726 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f4b0 728 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f4c8 730 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f4e0 732 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f4f8 734 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f510 736 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f528 738 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f540 740 0x80a8dff8 0x0 **
> pond20.20: 0x80a8f558 742 0x80a8dff8 0x0 **
> pond20.20: 0x0 744 0x80a8dff8 0x0 **
> kernel 20: user page fault in 'pond20': addr 0 IP 4d49dc SP a80062b1140 error 0x6
>
>
>
> ________________________________________
> From: Kornilios Kourtis [kornilios.kourtis at inf.ethz.ch]
> Sent: Saturday, March 30, 2013 16:33
> To: Georgios Varisteas
> Cc: barrelfish-users at lists.inf.ethz.ch
> Subject: Re: [Barrelfish-users] [New release] free() error
>
> Hi Georgios,
>
> On Wed, Mar 27, 2013 at 08:10:22PM +0000, Georgios Varisteas wrote:
> > Hi,
> >
> > Using code that run before updating, I now get a page fault while
> > freeing memory. The same code runs correctly on linux and I get no
> > messages from valgrind neither. Thus it should be something internal.
> > kernel 20: user page fault in 'pond20': addr 0 IP 4d3c8d SP a80062b1120 error 0x6
> >
> > Although I attached the disassembled portion below, I assume the error
> > is at ./lib/barrelfish/slot_alloc/single_slot_alloc.c:117.
> >
> > Actually this is the last of a series of 3 calls to free() and since
> > allocations were also done consecutively the addresses are consecutive.
> >
> > I can spend time to fix this myself but I'd like some pointers.
> >
> > cheers,
> > Georgios
> >
> >
> > 00000000004d3b10 <sfree>:
> [snip]
> > 4d3c84: e8 27 64 f9 ff callq 46a0b0 <slab_alloc>
> > 4d3c89: 49 89 46 08 mov %rax,0x8(%r14)
> >
> > ->4d3c8d: 44 89 28 mov %r13d,(%rax)
>
> Not sure how much this will help, but the problem seems to be that
> slab_alloc() returns NULL, which is not checked in sfree(), causing a
> segfault when trying to dereference the returned pointer.
>
> slab_alloc() returns NULL if:
> a) no refill function (->refill_func) exists, or
> b) calling ->refill_func did not result in new free blocks.
>
> A first suggestion would be to try and see if we are dealing with a) or
> b).
>
> cheers,
> Kornilios.
>
> --
> Kornilios Kourtis
>
> _______________________________________________
> Barrelfish-users mailing list
> Barrelfish-users at lists.inf.ethz.ch
> https://lists.inf.ethz.ch/mailman/listinfo/barrelfish-users
--
Kornilios Kourtis
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