bisecting cause commit starting from bbf5c979011a099af5dc76498918ed7df445635b building syzkaller on d32b0bbf2f8cfe548553c4012e2c0f79040d999f testing commit bbf5c979011a099af5dc76498918ed7df445635b with gcc (GCC) 8.1.0 kernel signature: 8b840a65c78b0069643e730d51add47c03bb17ca18d7520c6a773e50e2cb1055 all runs: crashed: WARNING in __writeback_inodes_sb_nr testing release v5.8 testing commit bcf876870b95592b52519ed4aafcf9d95999bc9c with gcc (GCC) 8.1.0 kernel signature: c8e76bd576d17a3da7d4c04675d695d50c50a29d2841a6f17b484f81b639c306 all runs: crashed: WARNING in __writeback_inodes_sb_nr testing release v5.7 testing commit 3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162 with gcc (GCC) 8.1.0 kernel signature: 6c79a1274846e1dd35e051f11e5da60649d2f713717c461e4116c55f65b7924c all runs: crashed: WARNING in __writeback_inodes_sb_nr testing release v5.6 testing commit 7111951b8d4973bda27ff663f2cf18b663d15b48 with gcc (GCC) 8.1.0 kernel signature: 31cb6ec86e01e8d2d4c6c243fb9d4b5e3a51b51fb0a78db6365b00d2381e9dc2 all runs: crashed: WARNING in __writeback_inodes_sb_nr testing release v5.5 testing commit d5226fa6dbae0569ee43ecfc08bdcd6770fc4755 with gcc (GCC) 8.1.0 kernel signature: ee6d31c410c6a9c95c364337774192866a3f8e6eb95d2e0a8e905e81ddddb9a3 all runs: crashed: WARNING in __writeback_inodes_sb_nr testing release v5.4 testing commit 219d54332a09e8d8741c1e1982f5eae56099de85 with gcc (GCC) 8.1.0 kernel signature: c884ac6ac81875c7ea10781f22397d722e91708db5eed37129946e0cfe28bc72 all runs: crashed: WARNING in __writeback_inodes_sb_nr testing release v5.3 testing commit 4d856f72c10ecb060868ed10ff1b1453943fc6c8 with gcc (GCC) 8.1.0 kernel signature: 65d2cbf91e25155d7a7b2b15f0c9e9a7fd39b232e78d8edb58ea3e8cc3e3d4c3 all runs: crashed: WARNING in __writeback_inodes_sb_nr testing release v5.2 testing commit 0ecfebd2b52404ae0c54a878c872bb93363ada36 with gcc (GCC) 8.1.0 kernel signature: acfbe3f2a17e328a185a3e5d3df112e857a8808e3bd5bf95db1a2be729f32f18 run #0: crashed: WARNING in __writeback_inodes_sb_nr run #1: crashed: WARNING in __writeback_inodes_sb_nr run #2: crashed: WARNING in __writeback_inodes_sb_nr run #3: crashed: WARNING in __writeback_inodes_sb_nr run #4: crashed: WARNING in __writeback_inodes_sb_nr run #5: crashed: WARNING in __writeback_inodes_sb_nr run #6: crashed: WARNING in __writeback_inodes_sb_nr run #7: crashed: WARNING in __writeback_inodes_sb_nr run #8: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #9: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! testing release v5.1 testing commit e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd with gcc (GCC) 8.1.0 kernel signature: 59332160b7da194918fe53ffdc2361c99cf48832e7ac230e54d6370c11f4172d run #0: crashed: WARNING in __writeback_inodes_sb_nr run #1: crashed: WARNING in __writeback_inodes_sb_nr run #2: crashed: WARNING in __writeback_inodes_sb_nr run #3: crashed: WARNING in __writeback_inodes_sb_nr run #4: crashed: WARNING in __writeback_inodes_sb_nr run #5: crashed: WARNING in __writeback_inodes_sb_nr run #6: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #7: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #8: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #9: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! testing release v5.0 testing commit 1c163f4c7b3f621efff9b28a47abb36f7378d783 with gcc (GCC) 8.1.0 kernel signature: 4fc42aede2b52d2b5b0f69fbcc1068668bf2ad0a0a4f8856982df3c479026d9d run #0: crashed: WARNING in __writeback_inodes_sb_nr run #1: crashed: WARNING in __writeback_inodes_sb_nr run #2: crashed: WARNING in __writeback_inodes_sb_nr run #3: crashed: WARNING in __writeback_inodes_sb_nr run #4: crashed: WARNING in __writeback_inodes_sb_nr run #5: crashed: WARNING in __writeback_inodes_sb_nr run #6: crashed: WARNING in __writeback_inodes_sb_nr run #7: crashed: WARNING in __writeback_inodes_sb_nr run #8: OK run #9: OK testing release v4.20 testing commit 8fe28cb58bcb235034b64cbbb7550a8a43fd88be with gcc (GCC) 8.1.0 certs/signing_key.pem: Permission denied testing release v4.19 testing commit 84df9525b0c27f3ebc2ebb1864fa62a97fdedb7d with gcc (GCC) 8.1.0 certs/signing_key.pem: Permission denied testing release v4.18 testing commit 94710cac0ef4ee177a63b5227664b38c95bbf703 with gcc (GCC) 8.1.0 certs/signing_key.pem: Permission denied testing release v4.17 testing commit 29dcea88779c856c7dc92040a0c01233263101d4 with gcc (GCC) 8.1.0 certs/signing_key.pem: Permission denied testing release v4.16 testing commit 0adb32858b0bddf4ada5f364a84ed60b196dbcda with gcc (GCC) 8.1.0 certs/signing_key.pem: Permission denied testing release v4.15 testing commit d8a5b80568a9cb66810e75b182018e9edb68e8ff with gcc (GCC) 8.1.0 certs/signing_key.pem: Permission denied testing release v4.14 testing commit bebc6082da0a9f5d47a1ea2edc099bf671058bd4 with gcc (GCC) 8.1.0 certs/signing_key.pem: Permission denied testing release v4.13 testing commit 569dbb88e80deb68974ef6fdd6a13edb9d686261 with gcc (GCC) 8.1.0 certs/signing_key.pem: Permission denied testing release v4.12 testing commit 6f7da290413ba713f0cdd9ff1a2a9bb129ef4f6c with gcc (GCC) 8.1.0 certs/signing_key.pem: Permission denied testing release v4.11 testing commit a351e9b9fc24e982ec2f0e76379a49826036da12 with gcc (GCC) 7.3.0 certs/signing_key.pem: Permission denied testing release v4.10 testing commit c470abd4fde40ea6a0846a2beab642a578c0b8cd with gcc (GCC) 5.5.0 certs/signing_key.pem: Permission denied testing release v4.9 testing commit 69973b830859bc6529a7a0468ba0d80ee5117826 with gcc (GCC) 5.5.0 certs/signing_key.pem: Permission denied testing release v4.8 testing commit c8d2bc9bc39ebea8437fd974fdbc21847bb897a3 with gcc (GCC) 5.5.0 certs/signing_key.pem: Permission denied testing release v4.7 testing commit 523d939ef98fd712632d93a5a2b588e477a7565e with gcc (GCC) 5.5.0 certs/signing_key.pem: Permission denied testing release v4.6 testing commit 2dcd0af568b0cf583645c8a317dd12e344b1c72a with gcc (GCC) 5.5.0 certs/signing_key.pem: Permission denied revisions tested: 25, total time: 2h18m27.457310362s (build: 1h22m51.917128708s, test: 52m0.416167337s) the crash already happened on the oldest tested release commit msg: Linux 5.0 crash: WARNING in __writeback_inodes_sb_nr BTRFS warning (device ): duplicate device fsid:devid for f90cac8b-044b-4fa8-8bee-4b8d3da88dc2:1 old:/dev/loop5 new:/dev/loop0 BTRFS warning (device loop5): duplicate device fsid:devid for f90cac8b-044b-4fa8-8bee-4b8d3da88dc2:1 old:/dev/loop5 new:/dev/loop0 BTRFS info (device loop5): checking UUID tree WARNING: CPU: 1 PID: 8233 at fs/fs-writeback.c:2363 __writeback_inodes_sb_nr+0x223/0x270 fs/fs-writeback.c:2367 Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 8233 Comm: kworker/u4:8 Not tainted 5.0.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_unbound btrfs_async_reclaim_metadata_space Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x165/0x21a lib/dump_stack.c:113 panic+0x212/0x40b kernel/panic.c:214 __warn.cold.7+0x1b/0x38 kernel/panic.c:571 report_bug+0x1a4/0x200 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:178 [inline] do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:973 RIP: 0010:__writeback_inodes_sb_nr+0x223/0x270 fs/fs-writeback.c:2363 Code: 00 00 c7 40 14 00 00 00 00 48 8b 45 d0 65 48 33 04 25 28 00 00 00 75 33 48 81 c4 f0 00 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <0f> 0b e9 76 ff ff ff 48 89 c7 e8 8e 35 ed ff e9 07 ff ff ff 4c 89 RSP: 0018:ffff88808f717928 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 1ffff11011ee2f27 RCX: 1ffff110104289a6 RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff888082144d30 RBP: ffff88808f717a40 R08: ffffed10104289a7 R09: ffffed10104289a6 R10: ffffed10104289a6 R11: ffff888082144d37 R12: ffff88808f5a6900 R13: ffff888082144df0 R14: ffff88808f717958 R15: ffff888082144cc0 writeback_inodes_sb_nr fs/fs-writeback.c:2383 [inline] writeback_inodes_sb+0x22/0x30 fs/fs-writeback.c:2398 btrfs_start_delalloc_flush fs/btrfs/transaction.c:1901 [inline] btrfs_commit_transaction+0x1780/0x2480 fs/btrfs/transaction.c:2027 may_commit_transaction fs/btrfs/extent-tree.c:4889 [inline] flush_space+0x327/0xda0 fs/btrfs/extent-tree.c:4964 btrfs_async_reclaim_metadata_space+0x422/0x1060 fs/btrfs/extent-tree.c:5075 process_one_work+0x7b9/0x15e0 kernel/workqueue.c:2173 worker_thread+0x85/0xb60 kernel/workqueue.c:2319 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Kernel Offset: disabled Rebooting in 86400 seconds..