Suspected CL could 
https://chromium.googlesource.com/v8/v8/+/bb883395a814d10cee927eabe689a8070a40a86a%5E%21/src/heap/slot-set.h

Last updated by ulan@ weeks ago , please have a look and reassign if needed.

Thank you.

Regression range points to 

[heap] Reland uncommit unused large object page memory.

https://codereview.chromium.org/2109943003

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/5a8cfaf06df674c98944348441034267cbccaf79

commit 5a8cfaf06df674c98944348441034267cbccaf79
Author: ulan <ulan@chromium.org>
Date: Thu Jun 30 15:00:54 2016

Fix clearing of slots on large page uncommit

BUG= chromium:624544 
LOG=NO

Review-Url: https://codereview.chromium.org/2110213003
Cr-Commit-Position: refs/heads/master@{#37451}

[modify] https://crrev.com/5a8cfaf06df674c98944348441034267cbccaf79/src/heap/remembered-set.h
[modify] https://crrev.com/5a8cfaf06df674c98944348441034267cbccaf79/src/heap/slot-set.h
[modify] https://crrev.com/5a8cfaf06df674c98944348441034267cbccaf79/src/heap/spaces.cc
[modify] https://crrev.com/5a8cfaf06df674c98944348441034267cbccaf79/test/cctest/heap/test-heap.cc

ClusterFuzz has detected this issue as fixed in range 37450:37451.

Detailed report: https://cluster-fuzz.appspot.com/testcase?key=5730404023926784

Fuzzer: mbarbella_js_mutation
Job Type: linux_asan_d8_ignition_v8_arm_dbg
Platform Id: linux

Crash Type: CHECK failure
Crash Address: 
Crash State:
  slot >= 0 && slot <= kMaxSlots in slot-set.h
  
Regressed: V8: r37375:37376
Fixed: V8: r37450:37451

Minimized Testcase (0.19 Kb):
Download: https://cluster-fuzz.appspot.com/download/AMIfv97qZeT_EBolvYDkssmN70gBVoQU9Ikz53jEZk-PZs2OxQcf2y3RXHcXlFjOKU707oflzSIN8s0t90k4amm_-XRXIGQSWGHqGdNLkOTsK7MwkuXFleYVAYnOvQ8vBoZfzpRFt0-5j3E7VvQuSScIRNSwWK3rTw?testcase_id=5730404023926784
__v_0 = new Array(5000000);
__v_0.length = 23;
    let handler = new Proxy({}, {get: function() {
      switch (key) {
      }
    }});
  __v_0[2] = {c: 7};
function __f_2() {
}
for (x in __v_15) {
}


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If you suspect that the result above is incorrect, try re-doing that job on the test case report page.

ClusterFuzz testcase is verified as fixed, closing issue.

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