regression can't open file in 2.79 (crash) #52816

New Issue

mathieu menuet · 2017-09-18T16:15:33+02:00

mathieu menuet commented

2017-09-18 16:15:33 +02:00

System Information
Windows x64

Blender Version
Broken: 2.79
Worked: 2.74 to 2.78

Short description of error
Some files get an instant crash when trying to open in 2.79

Exact steps for others to reproduce the error
Try to open this file saved with 2.74
crash visibility layer 274.blend

**System Information** Windows x64 **Blender Version** Broken: 2.79 Worked: 2.74 to 2.78 **Short description of error** Some files get an instant crash when trying to open in 2.79 **Exact steps for others to reproduce the error** Try to open this file saved with 2.74 [crash visibility layer 274.blend](https://archive.blender.org/developer/F812984/crash_visibility_layer_274.blend)

mathieu menuet commented

2017-09-18 16:15:33 +02:00

Changed status to: 'Open'

mathieu menuet commented

2017-09-18 16:15:33 +02:00

Added subscriber: @bliblubli

Bastien Montagne commented

2017-09-18 20:01:30 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2017-09-18 20:01:30 +02:00

Cannot confirm that here on linux64, with a debug build of current master… can you check if you still get crash with the latest build from our buildbot?

Cannot confirm that here on linux64, with a debug build of current master… can you check if you still get crash with the latest build from [our buildbot](https://builder.blender.org/download)?

Ray molenkamp commented

2017-09-18 20:08:03 +02:00

Added subscriber: @LazyDodo

Ray molenkamp commented

2017-09-18 20:08:03 +02:00

I can repro when i enable the page heap on windows ( don't have time to extract a stackdump now sadly) so i'm pretty sure asan will catch this on linux as well.

Ray molenkamp commented

2017-09-18 21:19:57 +02:00

allright had some time, here's a stackdump

>	blender.exe!bvhtree_from_mesh_looptri_create_tree(float epsilon, int tree_type, int axis, const MVert * vert, const MLoop * mloop, const MLoopTri * looptri, const int looptri_num, const unsigned int * looptri_mask, int looptri_num_active) Line 1028	C

 	blender.exe!bvhtree_from_mesh_looptri(BVHTreeFromMesh * data, DerivedMesh * dm, float epsilon, int tree_type, int axis) Line 1171	C
 	blender.exe!shrinkwrap_get_tarmat(bConstraint * con, bConstraintOb * cob, bConstraintTarget * ct, float UNUSED_ctime) Line 3562	C
 	blender.exe!BKE_constraint_targets_for_solving_get(bConstraint * con, bConstraintOb * cob, ListBase * targets, float ctime) Line 4952	C
 	blender.exe!BKE_constraints_solve(ListBase * conlist, bConstraintOb * cob, float ctime) Line 5007	C
 	blender.exe!BKE_object_where_is_calc_time_ex(Scene * scene, Object * ob, float ctime, RigidBodyWorld * rbw, float[3] * r_originmat) Line 2100	C
 	blender.exe!BKE_object_where_is_calc_ex(Scene * scene, RigidBodyWorld * rbw, Object * ob, float[3] * r_originmat) Line 2138	C
 	blender.exe!BKE_object_handle_update_ex(EvaluationContext * eval_ctx, Scene * scene, Object * ob, RigidBodyWorld * rbw, const bool do_proxy_update) Line 2649	C
 	blender.exe!scene_update_object_func(TaskPool * pool, void * taskdata, int threadid) Line 1620	C
 	blender.exe!task_scheduler_thread_run(void * thread_p) Line 441	C

looptri- [x] is pointing to uninitialized ram.

allright had some time, here's a stackdump ``` > blender.exe!bvhtree_from_mesh_looptri_create_tree(float epsilon, int tree_type, int axis, const MVert * vert, const MLoop * mloop, const MLoopTri * looptri, const int looptri_num, const unsigned int * looptri_mask, int looptri_num_active) Line 1028 C blender.exe!bvhtree_from_mesh_looptri(BVHTreeFromMesh * data, DerivedMesh * dm, float epsilon, int tree_type, int axis) Line 1171 C blender.exe!shrinkwrap_get_tarmat(bConstraint * con, bConstraintOb * cob, bConstraintTarget * ct, float UNUSED_ctime) Line 3562 C blender.exe!BKE_constraint_targets_for_solving_get(bConstraint * con, bConstraintOb * cob, ListBase * targets, float ctime) Line 4952 C blender.exe!BKE_constraints_solve(ListBase * conlist, bConstraintOb * cob, float ctime) Line 5007 C blender.exe!BKE_object_where_is_calc_time_ex(Scene * scene, Object * ob, float ctime, RigidBodyWorld * rbw, float[3] * r_originmat) Line 2100 C blender.exe!BKE_object_where_is_calc_ex(Scene * scene, RigidBodyWorld * rbw, Object * ob, float[3] * r_originmat) Line 2138 C blender.exe!BKE_object_handle_update_ex(EvaluationContext * eval_ctx, Scene * scene, Object * ob, RigidBodyWorld * rbw, const bool do_proxy_update) Line 2649 C blender.exe!scene_update_object_func(TaskPool * pool, void * taskdata, int threadid) Line 1620 C blender.exe!task_scheduler_thread_run(void * thread_p) Line 441 C ``` looptri- [x] is pointing to uninitialized ram.

Bastien Montagne self-assigned this 2017-09-18 21:52:31 +02:00

Bastien Montagne commented

2017-09-18 21:52:31 +02:00

This smells like threading issues again, pretty sure running with -t 1 option is enough to get rid of the crash?

Will check on this more tomorrow, but could not reproduce the issue even with an debug/asan build here with master code.

This smells like threading issues again, pretty sure running with `-t 1` option is enough to get rid of the crash? Will check on this more tomorrow, but could not reproduce the issue even with an debug/asan build here with master code.

Ray molenkamp commented

2017-09-18 21:56:55 +02:00

Stack dump is from latest master, can confirm -t 1 gets rid of the crash.

Germano Cavalcante commented

2017-09-19 00:52:13 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2017-09-19 00:52:13 +02:00

I made a weird change in the code that seems to solve the problem:

diff --git a/source/blender/blenkernel/intern/cdderivedmesh.c b/source/blender/blenkernel/intern/cdderivedmesh.c
index ed10f905539..27c985a8306 100644
--- a/source/blender/blenkernel/intern/cdderivedmesh.c
+++ b/source/blender/blenkernel/intern/cdderivedmesh.c
@@ -1919,12 +1919,16 @@ void CDDM_recalc_looptri(DerivedMesh *dm)
 	const unsigned int totloop = dm->numLoopData;
 
 	DM_ensure_looptri_data(dm);
+	struct MLoopTri *array = dm->looptris.array;
+	dm->looptris.array = NULL;
 
 	BKE_mesh_recalc_looptri(
 	        cddm->mloop, cddm->mpoly,
 	        cddm->mvert,
 	        totloop, totpoly,
-	        cddm->dm.looptris.array);
+	        array);
+
+	dm->looptris.array = array;
 }
 
 static void cdDM_free_internal(CDDerivedMesh *cddm)

Apparently, since the condition: "if (dm->looptris.array) {" of the dm_getLoopTriArray function is out of the thread's mutex_lock, the dm->looptris.array can be used before being "fully written".

My solution was to leave dm->looptris.array NULL during the entire process of creating the looptris array.
(if I avoided malloc within DM_ensure_looptri_data would be more correct)

I made a weird change in the code that seems to solve the problem: ``` diff --git a/source/blender/blenkernel/intern/cdderivedmesh.c b/source/blender/blenkernel/intern/cdderivedmesh.c index ed10f905539..27c985a8306 100644 --- a/source/blender/blenkernel/intern/cdderivedmesh.c +++ b/source/blender/blenkernel/intern/cdderivedmesh.c @@ -1919,12 +1919,16 @@ void CDDM_recalc_looptri(DerivedMesh *dm) const unsigned int totloop = dm->numLoopData; DM_ensure_looptri_data(dm); + struct MLoopTri *array = dm->looptris.array; + dm->looptris.array = NULL; BKE_mesh_recalc_looptri( cddm->mloop, cddm->mpoly, cddm->mvert, totloop, totpoly, - cddm->dm.looptris.array); + array); + + dm->looptris.array = array; } static void cdDM_free_internal(CDDerivedMesh *cddm) ``` Apparently, since the condition: "`if (dm->looptris.array) {`" of the `dm_getLoopTriArray` function is out of the thread's mutex_lock, the `dm->looptris.array` can be used before being "fully written". My solution was to leave `dm->looptris.array` `NULL` during the entire process of creating the looptris array. (if I avoided malloc within `DM_ensure_looptri_data` would be more correct)

Bastien Montagne commented

2017-09-19 12:26:59 +02:00

Uh… good point didn’t thought about that kind of concurrency issue :P

Will try to find more generic way to do that (including other DM types), but that's clearly the way to go indeed.

Uh… good point didn’t thought about that kind of concurrency issue :P Will try to find more generic way to do that (including other DM types), but that's clearly the way to go indeed.

blender-admin commented

2017-09-19 13:57:46 +02:00

This issue was referenced by 9591b5f618

This issue was referenced by 9591b5f6182f754dc06e1aff43d6b8b675aa9bf4

Bastien Montagne commented

2017-09-19 14:12:37 +02:00

Changed status from 'Open' to: 'Resolved'

Bastien Montagne closed this issue

2017-09-19 14:12:37 +02:00

Bastien Montagne commented

2017-09-19 14:15:51 +02:00

Note that 9591b5f618 is tentative fix (based on @mano-wii's work), if one of you guys could confirm it fixes the issue would be great. ;)

Note that 9591b5f618 is tentative fix (based on @mano-wii's work), if one of you guys could confirm it fixes the issue would be great. ;)

Germano Cavalcante commented

2017-09-19 14:36:56 +02:00

Added subscriber: @Sergey

Germano Cavalcante commented

2017-09-19 14:36:56 +02:00

In #52816#460918, @mont29 wrote:
Note that 9591b5f618 is tentative fix (based on @mano-wii's work), if one of you guys could confirm it fixes the issue would be great. ;)

Well, it seems @Sergey came across the same bug, and found a workaround for adding another mutex to dm_getLoopTriArray -> 1a4442b3db

But applying only your solution also solves the bug

> In #52816#460918, @mont29 wrote: > Note that 9591b5f618 is tentative fix (based on @mano-wii's work), if one of you guys could confirm it fixes the issue would be great. ;) Well, it seems @Sergey came across the same bug, and found a workaround for adding another mutex to `dm_getLoopTriArray` -> 1a4442b3db But applying only your solution also solves the bug

Ray molenkamp commented

2017-09-19 14:57:19 +02:00

Tested with latest master, no more crash

mathieu menuet commented

2017-09-19 17:34:03 +02:00

Thanks for the quick fix, but maybe only one fix would be enough? Don't know if the 2 fixes together may decrease performance?

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regression can't open file in 2.79 (crash) #52816