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Date:   Mon, 21 Sep 2020 10:02:11 -0700
In-Reply-To: <20200921170055.GJ6756@twin.jikos.cz>
Message-ID: <000000000000c0140405afd5cf4a@google.com>
Subject: Re: Re: WARNING in btrfs_alloc_chunk
From:   syzbot <syzbot+f54bbed7adc7c7729120@syzkaller.appspotmail.com>
To:     David Sterba <dsterba@suse.cz>
Cc:     clm@fb.com, dsterba@suse.com, dsterba@suse.cz,
        josef@toxicpanda.com, linux-btrfs@vger.kernel.org,
        linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
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> On Mon, Sep 21, 2020 at 03:02:22AM -0700, syzbot wrote:
>> Hello,
>> 
>> syzbot found the following issue on:
>> 
>> HEAD commit:    325d0eab Merge branch 'akpm' (patches from Andrew)
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=142c89ab900000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=8d39f8ae68f9dcd5
>> dashboard link: https://syzkaller.appspot.com/bug?extid=f54bbed7adc7c7729120
>> compiler:       gcc (GCC) 10.1.0-syz 20200507
>> 
>> Unfortunately, I don't have any reproducer for this issue yet.
>> 
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+f54bbed7adc7c7729120@syzkaller.appspotmail.com
>> 
>> ------------[ cut here ]------------
>> gather_device_info: found more than 0 devices
>> WARNING: CPU: 1 PID: 26278 at fs/btrfs/volumes.c:4967 gather_device_info fs/btrfs/volumes.c:4967 [inline]
>> WARNING: CPU: 1 PID: 26278 at fs/btrfs/volumes.c:4967 btrfs_alloc_chunk+0x1a43/0x2000 fs/btrfs/volumes.c:5194
>> Kernel panic - not syncing: panic_on_warn set ...
>> CPU: 1 PID: 26278 Comm: syz-executor.2 Not tainted 5.9.0-rc5-syzkaller #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>> Call Trace:
>>  __dump_stack lib/dump_stack.c:77 [inline]
>>  dump_stack+0x198/0x1fd lib/dump_stack.c:118
>>  panic+0x382/0x7fb kernel/panic.c:231
>>  __warn.cold+0x20/0x4b kernel/panic.c:600
>>  report_bug+0x1bd/0x210 lib/bug.c:198
>>  handle_bug+0x38/0x90 arch/x86/kernel/traps.c:234
>>  exc_invalid_op+0x14/0x40 arch/x86/kernel/traps.c:254
>>  asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:536
>> RIP: 0010:gather_device_info fs/btrfs/volumes.c:4967 [inline]
>> RIP: 0010:btrfs_alloc_chunk+0x1a43/0x2000 fs/btrfs/volumes.c:5194
>> Code: ff ff 44 8b 7c 24 78 4c 89 0c 24 e8 17 06 67 fe 4c 8b 0c 24 48 c7 c6 c0 79 a6 88 48 c7 c7 40 67 a6 88 4c 89 ca e8 ff 41 37 fe <0f> 0b 4c 8b 0c 24 e9 f8 f0 ff ff 44 8b 7c 24 78 e8 e8 05 67 fe 31
>> RSP: 0018:ffffc900049072a8 EFLAGS: 00010286
>> RAX: 0000000000000000 RBX: ffff88809cbee000 RCX: 0000000000000000
>> RDX: ffff8880645462c0 RSI: ffffffff815f5a85 RDI: fffff52000920e47
>> RBP: dffffc0000000000 R08: 0000000000000001 R09: ffff8880ae7318e7
>> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
>> R13: 0000000002800000 R14: 0000000000010000 R15: 0000000000000001
>>  btrfs_chunk_alloc+0x3fe/0xaa0 fs/btrfs/block-group.c:3136
>>  find_free_extent_update_loop fs/btrfs/extent-tree.c:3796 [inline]
>>  find_free_extent+0x2090/0x2e60 fs/btrfs/extent-tree.c:4127
>>  btrfs_reserve_extent+0x166/0x460 fs/btrfs/extent-tree.c:4206
>>  btrfs_alloc_tree_block+0x203/0xee0 fs/btrfs/extent-tree.c:4603
>>  alloc_tree_block_no_bg_flush+0x1b6/0x250 fs/btrfs/ctree.c:987
>>  __btrfs_cow_block+0x3e0/0x10c0 fs/btrfs/ctree.c:1042
>>  btrfs_cow_block+0x2c1/0x8a0 fs/btrfs/ctree.c:1487
>>  commit_cowonly_roots+0x129/0xc70 fs/btrfs/transaction.c:1184
>>  btrfs_commit_transaction+0xde0/0x2830 fs/btrfs/transaction.c:2272
>>  btrfs_commit_super+0xc1/0x100 fs/btrfs/disk-io.c:4021
>>  close_ctree+0x2cd/0x6cb fs/btrfs/disk-io.c:4084
>>  generic_shutdown_super+0x144/0x370 fs/super.c:464
>>  kill_anon_super+0x36/0x60 fs/super.c:1108
>>  btrfs_kill_super+0x38/0x50 fs/btrfs/super.c:2265
>>  deactivate_locked_super+0x94/0x160 fs/super.c:335
>>  deactivate_super+0xad/0xd0 fs/super.c:366
>>  cleanup_mnt+0x3a3/0x530 fs/namespace.c:1118
>>  task_work_run+0xdd/0x190 kernel/task_work.c:141
>>  tracehook_notify_resume include/linux/tracehook.h:188 [inline]
>>  exit_to_user_mode_loop kernel/entry/common.c:163 [inline]
>>  exit_to_user_mode_prepare+0x1e1/0x200 kernel/entry/common.c:190
>>  syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:265
>>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>> RIP: 0033:0x460027
>> Code: 64 89 04 25 d0 02 00 00 58 5f ff d0 48 89 c7 e8 2f be ff ff 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 fd 89 fb ff c3 66 2e 0f 1f 84 00 00 00 00
>> RSP: 002b:00007ffd0b14c408 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
>> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000460027
>> RDX: 0000000000403188 RSI: 0000000000000002 RDI: 00007ffd0b14c4b0
>> RBP: 00000000000000ce R08: 0000000000000000 R09: 000000000000000a
>> R10: 0000000000000005 R11: 0000000000000246 R12: 00007ffd0b14d540
>> R13: 0000000002358a60 R14: 0000000000000000 R15: 00007ffd0b14d540
>> Kernel Offset: disabled
>> Rebooting in 86400 seconds..
>
> #syz test: git://github.com/kdave/btrfs-devel.git misc-5.9

This crash does not have a reproducer. I cannot test it.