**System Information**
Operating system: Linux-4.15.0-55-generic-x86_64-with-debian-stretch-sid 64 Bits
Graphics card: GeForce GTX 750 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 384.130
**Blender Version**
Broken: version: 2.81 (sub 4), branch: master, commit date: 2019-09-02 15:37, hash: `rB283d96de1170`
Worked: 2.80 official
**Short description of error**
Interaction with a particular object - such as entering/exiting edit mode or adjusting modifiers (or eventually after rendering/baking an arbitrary number of times) - causes Blender to crash.
**Exact steps for others to reproduce the error**
Download the attached .blend file and open it.
The object concerned is named Circle. It is a long thin cylinder with a spiral effect made using modifiers. It is already selected.
{F7714451}
Cause a crash by doing one of the following:
* **Transform the object** (G/R/S). Should crash immediately.
* **Enter edit mode** (tab). Should crash immediately, or on exit edit mode.
* **Adjust any modifiers properties or visibility**. Should crash immediately.
* **Toggle "Disable in Viewports" off and on in outliner**. Should crash after toggling back on.
* **Render** (F12). Each render should take about a second. It should crash after about 4 renders.
* **Shift-select the object BakeTarget and bake**. As with render, it should crash after about 4 bakes.
**Extra Info**
The object was made inside Blender (hard to say exactly when, but definitely late-june to mid-august) in master branch builds. It can be interacted with without any apparent issues in official 2.80 build.
Terminal output in case of crash on enter edit mode:
```
Read blend: /home/thomas/Documents/Blender/objectInteractCrash.blend
Writing: /tmp/objectInteractCrash.crash.txt
Segmentation fault
```
(If it doesn't crash immediately, you'll have a couple of "couldn't unmap memory" messages.)
Contents of objectInteractCrash.crash.txt:
```
# Blender 2.81 (sub 4), Commit date: 2019-09-02 15:37, Hash 283d96de1170
bpy.ops.object.editmode_toggle() # Operator
# backtrace
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BLI_system_backtrace+0x1d) [0x14c484d]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x12a9849]
/lib/x86_64-linux-gnu/libc.so.6(+0x354b0) [0x7ff0db6724b0]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BLI_bvhtree_find_nearest_ex+0xd5) [0x1485de5]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x2bf0377]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x14c5198]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BLI_task_parallel_range+0x194) [0x14c5fe4]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x2bf0e73]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x143c55b]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x143cc32]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(makeDerivedMesh+0x72) [0x143cd02]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BKE_object_handle_data_update+0xfc) [0x139a9dc]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BKE_object_eval_uber_data+0x2e) [0x139af1e]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x14e182c]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BLI_task_pool_work_and_wait+0x1a4) [0x14c5824]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(_ZN3DEG23deg_evaluate_on_refreshEPNS_9DepsgraphE+0x19b) [0x14e1a9b]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(DEG_evaluate_on_refresh+0x52) [0x14cc162]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x13d0f73]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(wm_event_do_depsgraph+0xc3) [0x16755c3]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(wm_event_do_refresh_wm_and_depsgraph+0x87) [0x1675727]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(wm_event_do_notifiers+0x472) [0x167b052]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(WM_main+0x28) [0x1671618]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(main+0x2fe) [0x1215dee]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0) [0x7ff0db65d830]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x12a616c]
```
Terminal output in case of crash from rendering a few times:
```
Read blend: /home/thomas/Documents/Blender/objectInteractCrash.blend
Couldn't unmap memory
Couldn't unmap memory
Couldn't unmap memory
Couldn't unmap memory
Couldn't unmap memory
Writing: /tmp/objectInteractCrash.crash.txt
Segmentation fault
```
The number of "couldn't unmap memory" messages generally correspond to the number of renders (though sometimes not?) On one occasion Blender hanged on the render rather than crashing.
Contents of objectInteractCrash.crash.txt:
```
# Blender 2.81 (sub 4), Commit date: 2019-09-02 15:37, Hash 283d96de1170
# backtrace
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BLI_system_backtrace+0x1d) [0x14c484d]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x12a9849]
/lib/x86_64-linux-gnu/libc.so.6(+0x354b0) [0x7f0a77a884b0]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(MEM_lockfree_allocN_len+0x5) [0x151dac5]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(MEM_lockfree_freeN+0x10) [0x151daf0]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BLI_bvhtree_free+0x47) [0x1485477]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x144512d]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BLI_linklist_free+0x2f) [0x1486b1f]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(bvhcache_free+0x13) [0x1447af3]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BKE_mesh_runtime_clear_geometry+0x10) [0x1373df0]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BKE_mesh_runtime_clear_cache+0x68) [0x1373ee8]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BKE_mesh_clear_geometry+0x13) [0x13669e3]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BKE_mesh_free+0x9) [0x1366af9]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BKE_mesh_eval_delete+0x14) [0x1366b34]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BKE_object_free_derived_caches+0x16d) [0x13964dd]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(BKE_object_free+0x20) [0x13966f0]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(_ZN3DEG32deg_free_copy_on_write_datablockEP2ID+0xdb) [0x14e206b]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(_ZN3DEG6IDNode7destroyEv+0x36) [0x14e9686]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(_ZN3DEG9Depsgraph26clear_id_nodes_conditionalERKSt8functionIFb7ID_TypeEE+0x73) [0x14c91e3]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(_ZN3DEG9Depsgraph14clear_id_nodesEv+0x6a) [0x14c926a]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(_ZN3DEG9DepsgraphD1Ev+0xd) [0x14c932d]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(DEG_graph_free+0xe) [0x14c956e]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(RE_engine_free_blender_memory+0x2c) [0x1554d4c]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(_ZN3ccl14BlenderSession6renderERN2BL9DepsgraphE+0x1573) [0x16b2973]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x16a50bd]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(_PyMethodDef_RawFastCallKeywords+0x2b9) [0x18acfb9]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(_PyCFunction_FastCallKeywords+0x25) [0x18ad075]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(_PyEval_EvalFrameDefault+0x7468) [0x12a40a8]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x129bb90]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(_PyEval_EvalFrameDefault+0x88dc) [0x12a551c]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x129bb90]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(_PyFunction_FastCallDict+0x2a6) [0x18aca36]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x154192e]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x1617df1]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(RE_engine_render+0x332) [0x15548e2]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x1556041]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x1558d80]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender(RE_RenderFrame+0x114) [0x1559704]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x407f3d4]
/home/thomas/Downloads/blender-2.81-283d96de1170-linux-glibc217-x86_64/blender() [0x1686522]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x76ba) [0x7f0a790cd6ba]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d) [0x7f0a77b5a41d]
```