问题现象
- 复现步骤
- 手机(Android 8.0, build id为opr6.170623.013)
- 复现场景一: app crash
- 选择一个大的txt文档，如：228k.txt
- 用html方式打开
- 打开后长按内容，点击全选，后点击分享到信息
- 选择号码后等待
- com.android.messaging进程几乎必现native crash
- 复现场景二: system_server crash
- 执行MSR压力测试
- system_server高概率出现native crash
定位分析
- 相关log
- tombstone
ABI: 'arm' pid: 24785, tid: 24795, name: HeapTaskDaemon >>> system_server <<< signal 6 (SIGABRT), code -6 (SI_TKILL), fault addr -------- Abort message: 'utils.cc:123] 12c00000-52c00000 rw-p 00000000 00:05 3180718 /dev/ashmem/dalvik-main space (region space) (deleted)' r0 00000000 r1 000060db r2 00000006 r3 00000008 r4 000060d1 r5 000060db r6 9bbc11d0 r7 0000010c r8 0000000b r9 9bbc1231 sl 0000000a fp 9bbc1230 ip 00000000 sp 9bbc11c0 lr b4fee417 pc b501e97c cpsr 200f0010 d0 2e656d69746e7572 d1 3031306666646631 d2 3135373066383036 d3 6f5f646c65696638 d4 6636633537373864 d5 6636633535373839 d6 6636633538373837 d7 363533613338317c d8 0000000000000000 d9 0000000000000000 d10 0000000000000000 d11 0000000000000000 d12 0000000000000000 d13 0000000000000000 d14 0000000000000000 d15 0000000000000000 d16 2e74736973726570 d17 2e6761742e676f6c d18 00000000c3394019 d19 000000005c000000 d20 0000000000000000 d21 000000000000005c d22 0000000400000004 d23 0000000400000004 d24 000022c1000002c1 d25 000062c1000042c1 d26 000022c0000002c0 d27 000062c0000042c0 d28 720410f8720410f0 d29 7204110872041100 d30 0000001806897c20 d31 7204110872041100 scr 20000013 backtrace: #00 pc 0004a97c /system/lib/libc.so (tgkill+12) #01 pc 0001a413 /system/lib/libc.so (abort+54) #02 pc 003385df /system/lib/libart.so (_ZN3art7Runtime5AbortEPKc+230) #03 pc 00338c6f /system/lib/libart.so (_ZN3art7Runtime7AborterEPKc+10) #04 pc 003efacd /system/lib/libart.so (_ZN7android4base10LogMessageD1Ev+456) #05 pc 001c1c3f /system/lib/libart.so (_ZNK3art2gc12Verification17LogHeapCorruptionENS_6ObjPtrINS_6mirror6ObjectEEENS_12MemberOffsetEPS4_b+926) #06 pc 001769fb /system/lib/libart.so (_ZN3art2gc9collector17ConcurrentCopying13MarkNonMovingEPNS_6mirror6ObjectES5_NS_12MemberOffsetE+290) #07 pc 00178097 /system/lib/libart.so (_ZN3art6mirror6Object15VisitReferencesILb1ELNS_17VerifyObjectFlagsE0ELNS_17ReadBarrierOptionE1ENS_2gc9collector17ConcurrentCopying16RefFieldsVisitorES8_EEvRKT2_RKT3_+218) #08 pc 00173537 /system/lib/libart.so (_ZN3art2gc9collector17ConcurrentCopying19ProcessMarkStackRefEPNS_6mirror6ObjectE+98) #09 pc 00173077 /system/lib/libart.so (_ZN3art2gc9collector17ConcurrentCopying20ProcessMarkStackOnceEv+402) #10 pc 00172ed7 /system/lib/libart.so (_ZN3art2gc9collector17ConcurrentCopying16ProcessMarkStackEv+18) #11 pc 0016e695 /system/lib/libart.so (_ZN3art2gc9collector17ConcurrentCopying12MarkingPhaseEv+456) #12 pc 0016dc75 /system/lib/libart.so (_ZN3art2gc9collector17ConcurrentCopying9RunPhasesEv+540) #13 pc 0017ccc5 /system/lib/libart.so (_ZN3art2gc9collector16GarbageCollector3RunENS0_7GcCauseEb+268) #14 pc 00197adf /system/lib/libart.so (_ZN3art2gc4Heap22CollectGarbageInternalENS0_9collector6GcTypeENS0_7GcCauseEb+2726) #15 pc 001a2f2f /system/lib/libart.so (_ZN3art2gc4Heap12ConcurrentGCEPNS_6ThreadENS0_7GcCauseEb+70) #16 pc 001a8949 /system/lib/libart.so (_ZN3art2gc4Heap16ConcurrentGCTask3RunEPNS_6ThreadE+20) #17 pc 001c147b /system/lib/libart.so (_ZN3art2gc13TaskProcessor11RunAllTasksEPNS_6ThreadE+30) #18 pc 7049a4cb /data/dalvik-cache/arm/system@[email protected] (offset 0x9a3000)
- tombstone
初步分析
-
gdb 堆栈
(gdb) bt #0 tgkill () at bionic/libc/arch-arm/syscalls/tgkill.S:10 #1 0xb4fee416 in abort () at bionic/libc/bionic/abort.cpp:49 #2 0xb206e5e2 in art::Runtime::Abort (msg=) at art/runtime/runtime.cc:523 #3 0xb206ec72 in art::Runtime::Aborter (abort_message=0x979bd380 "GC tried to mark invalid reference 0x17\nref=0x17 \nholder=0x13780000 klass=0x6f353a18(java.lang.Class ::operator()(char const*) const (this= , __arg=0x979bd380 "GC tried to mark invalid reference 0x17\nref=0x17 \nholder=0x13780000 klass=0x6f353a18(java.lang.Class , holder=..., offset=..., ref=0x17, fatal= ) at external/libcxx/include/new:235 #7 0xb1eac9fe in art::gc::collector::ConcurrentCopying::MarkNonMoving (this=0xb22c3700, ref=0x17, holder=0x13780000, offset=...) at art/runtime/gc/collector/concurrent_copying.cc:2435 #8 0xb1eae09a in art::gc::collector::ConcurrentCopying::RefFieldsVisitor::operator() (this= , obj=0x13780000, offset=...) at art/runtime/gc/collector/concurrent_copying.cc:1911 #9 art::mirror::ObjectArray ) at art/runtime/mirror/object_array-inl.h:373 #10 art::mirror::Object::VisitReferences ) at art/runtime/gc/collector/concurrent_copying.cc:1950 #12 art::gc::collector::ConcurrentCopying::ProcessMarkStackRef (this=0xb22c3700, to_ref=0x13780000) at art/runtime/gc/collector/concurrent_copying.cc:1446 #13 0xb1ea907a in art::gc::collector::ConcurrentCopying::ProcessMarkStackOnce (this=0xb22c3700) at art/runtime/gc/collector/concurrent_copying.cc:1347 #14 0xb1ea8eda in art::gc::collector::ConcurrentCopying::ProcessMarkStack (this=0xb22c3700) at art/runtime/gc/collector/concurrent_copying.cc:1326 #15 0xb1ea4696 in art::gc::collector::ConcurrentCopying::MarkingPhase (this=0xb22c3700) at art/runtime/gc/collector/concurrent_copying.cc:756 #16 0xb1ea3c78 in art::gc::collector::ConcurrentCopying::RunPhases (this=0xb22c3700) at art/runtime/gc/collector/concurrent_copying.cc:169 #17 0xb1eb2cc6 in art::gc::collector::GarbageCollector::Run (this= , gc_cause=art::gc::kGcCauseBackground, clear_soft_references= ) at art/runtime/gc/collector/garbage_collector.cc:95 #18 0xb1ecdae2 in art::gc::Heap::CollectGarbageInternal (this=0xb22fd400, gc_type= , gc_cause=art::gc::kGcCauseBackground, clear_soft_references= ) at art/runtime/gc/heap.cc:2748 #19 0xb1ed8f32 in art::gc::Heap::ConcurrentGC (this=0xb22fd400, self= , cause=art::gc::kGcCauseBackground, force_full= ) at art/runtime/gc/heap.cc:3752 #20 0xb1ede94c in art::gc::Heap::ConcurrentGCTask::Run (this= , self=0x60db) at art/runtime/gc/heap.cc:3713 #21 0xb1ef747c in art::gc::TaskProcessor::RunAllTasks (this=0xb221eb80, self=0xaac57200) at art/runtime/gc/task_processor.cc:124 #22 0x7049a4cc in ?? () -
log分析
#3报出的abort_message完整log为 (gdb) p (char *)0x979bd380 $1 = 0x979bd380 "GC tried to mark invalid reference 0x17\nref=0x17\nholder=0x13780000 klass=0x6f353a18(java.lang.Class -
查看当前obj=0x17
(gdb) x /4xw 0x13780000+262168 0x137c0018: 0x00000017 0x00300032 0x00200030 0x00200035
对比实验
- Nexus 6p无法复现
- 通过添加log, 发现没有走GC操作
深入分析
-
查看obj相关的region[]
... ... $49 = { idx_ = 46, begin_ = 0x13780000 "\030:5o", top_ = {}, }, end_ = 0x137c0000 "\260\207(o", state_ = art::gc::space::RegionSpace::RegionState::kRegionStateLarge, type_ = art::gc::space::RegionSpace::RegionType::kRegionTypeUnevacFromSpace, objects_allocated_ = { }, }, }, alloc_time_ = 13, live_bytes_ = 0, is_newly_allocated_ = false, is_a_tlab_ = false, thread_ = 0x0 } $50 = { idx_ = 47, begin_ = 0x137c0000 "\260\207(o", top_ = { }, }, end_ = 0x13800000 "\260\207(o", state_ = art::gc::space::RegionSpace::RegionState::kRegionStateAllocated, type_ = art::gc::space::RegionSpace::RegionType::kRegionTypeUnevacFromSpace, objects_allocated_ = { }, }, }, alloc_time_ = 14, live_bytes_ = 0, is_newly_allocated_ = true, is_a_tlab_ = false, thread_ = 0x0 } ... ... 可看到，
- regions_[46]和regions_[47]原本是一个large object, regions_[46]的top_已指向regions_[47],
- regions_[47]当前的状态为art::gc::space::RegionSpace::RegionState::kRegionStateAllocated, 表示已分配出去，理论上来讲应该是art::gc::space::RegionSpace::RegionState::kRegionStateLargeTail
- regions_[46]的alloc_time是13, regions_[47]的alloc_time是14, 说明regions_[47]后续在使用过程中又被分配出去了．
-
网络求助
-
stackoverflow
https://stackoverflow.com/questions/45978282/android-o8-0-access-network-or-database-cause-native-crashheapdaemontask-dead
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Google issue tracker
- https://issuetracker.google.com/issues/65147194
- https://issuetracker.google.com/issues/65268761
- https://issuetracker.google.com/issues/37187694(没有权限访问)
其中在65268761, Google回复已解决，但patch会在未来的release中提供．
看这几个issue的提交和回复时间，也都集中8月底~9月初，就是opr6.170623.013发布后的这几天．
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Goolge ART求助
向Google ART的Nicolas Geoffray发一封求助邮件，描述复现和分析详情，很快收到回复(12分钟)．
Nicolas说此问题已解决，并提供了解决方案的链接．
Hi Tim, The change you're looking for is: https://android-review.googlesource.com/#/c/platform/art/+/430379/ Thanks for your links. And sorry you got hit by the bug.同时，Nicolas又更新了https://issuetracker.google.com/issues/65268761
[email protected]
解决方案
-
patch
https://android-review.googlesource.com/#/c/platform/art/+/430379/
-
验证
- 分享228k.txt至message,不再crash
- MSR压力测试，手机不再重启