On Mon, Jul 3, 2023 at 7:34 PM syzbot <syzbot+adac949c4246513f0dc6@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: b19edac5992d Merge tag 'nolibc.2023.06.22a' of git://git.k.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=17e0cfe0a80000 > kernel config: https://syzkaller.appspot.com/x/.config?x=33c8c2baba1cfc7e > dashboard link: https://syzkaller.appspot.com/bug?extid=adac949c4246513f0dc6 > compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1562a47f280000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/e1a4f239105a/disk-b19edac5.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/25776c3e9785/vmlinux-b19edac5.xz > kernel image: https://storage.googleapis.com/syzbot-assets/ca7e959d451d/bzImage-b19edac5.xz > mounted in repro #1: https://storage.googleapis.com/syzbot-assets/2926fe9a4819/mount_0.gz > mounted in repro #2: https://storage.googleapis.com/syzbot-assets/da38c75be578/mount_17.gz > > The issue was bisected to: > > commit 751a27615ddaaf95519565d83bac65b8aafab9e8 > Author: Filipe Manana <fdmanana@xxxxxxxx> > Date: Thu Jun 8 10:27:49 2023 +0000 > > btrfs: do not BUG_ON() on tree mod log failures at btrfs_del_ptr() If the bisection is correct, then it means before that commit we would hit a BUG_ON(), which is definitely not better... > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15196068a80000 > final oops: https://syzkaller.appspot.com/x/report.txt?x=17196068a80000 > console output: https://syzkaller.appspot.com/x/log.txt?x=13196068a80000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+adac949c4246513f0dc6@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: 751a27615dda ("btrfs: do not BUG_ON() on tree mod log failures at btrfs_del_ptr()") > > assertion failed: 0, in fs/btrfs/relocation.c:2011 > ------------[ cut here ]------------ > kernel BUG at fs/btrfs/relocation.c:2011! I don't see how this can be related to removing the BUG_ON() in del_ptr(), aborting the transaction and propagating the error up the call chain. So it seems not hitting the BUG_ON()'s removed by that commit may somehow trigger this assertion failure in an error path of relocation. But this assertion is in a path that is able to handle the error: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/btrfs/relocation.c?h=v6.4#n2011 The ASSERT(0) is there to make sure developers are notified of this unexpected case. Replacing it with a WARN_ON() would prevent the crash when CONFIG_BTRFS_ASSERT=y, but syzbot would still complain about a warning/stack trace, even if it doesn't trigger a crash. So I'm not sure if we can keep syzbot always happy all the time for all cases. > invalid opcode: 0000 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 7243 Comm: syz-executor.3 Not tainted 6.4.0-syzkaller-01312-gb19edac5992d #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023 > RIP: 0010:merge_reloc_roots+0x98b/0x9a0 fs/btrfs/relocation.c:2011 > Code: cb d1 10 07 0f 0b e8 84 9d ed fd 48 c7 c7 60 45 2b 8b 48 c7 c6 c0 50 2b 8b 48 c7 c2 e0 45 2b 8b b9 db 07 00 00 e8 a5 d1 10 07 <0f> 0b e8 7e 12 13 07 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 41 > RSP: 0018:ffffc9000656f760 EFLAGS: 00010246 > RAX: 0000000000000032 RBX: ffff88806a59a030 RCX: a7b6d3c4bc715b00 > RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000 > RBP: ffffc9000656f870 R08: ffffffff816efd9c R09: fffff52000cadea1 > R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888079e16558 > R13: ffff888079e16000 R14: ffff88806a59a000 R15: dffffc0000000000 > FS: 00007f62d8f56700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f7ba56f1000 CR3: 000000001a7d0000 CR4: 00000000003506f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > relocate_block_group+0xa68/0xcd0 fs/btrfs/relocation.c:3751 > btrfs_relocate_block_group+0x7ab/0xd70 fs/btrfs/relocation.c:4087 > btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3283 > __btrfs_balance+0x1b06/0x2690 fs/btrfs/volumes.c:4018 > btrfs_balance+0xbdb/0x1120 fs/btrfs/volumes.c:4402 > btrfs_ioctl_balance+0x496/0x7c0 fs/btrfs/ioctl.c:3604 > vfs_ioctl fs/ioctl.c:51 [inline] > __do_sys_ioctl fs/ioctl.c:870 [inline] > __se_sys_ioctl+0xf8/0x170 fs/ioctl.c:856 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > RIP: 0033:0x7f62d828c389 > Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007f62d8f56168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 00007f62d83abf80 RCX: 00007f62d828c389 > RDX: 00000000200003c0 RSI: 00000000c4009420 RDI: 0000000000000006 > RBP: 00007f62d82d7493 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 00007ffedd8614bf R14: 00007f62d8f56300 R15: 0000000000022000 > </TASK> > Modules linked in: > ---[ end trace 0000000000000000 ]--- > RIP: 0010:merge_reloc_roots+0x98b/0x9a0 fs/btrfs/relocation.c:2011 > Code: cb d1 10 07 0f 0b e8 84 9d ed fd 48 c7 c7 60 45 2b 8b 48 c7 c6 c0 50 2b 8b 48 c7 c2 e0 45 2b 8b b9 db 07 00 00 e8 a5 d1 10 07 <0f> 0b e8 7e 12 13 07 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 41 > RSP: 0018:ffffc9000656f760 EFLAGS: 00010246 > RAX: 0000000000000032 RBX: ffff88806a59a030 RCX: a7b6d3c4bc715b00 > RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000 > RBP: ffffc9000656f870 R08: ffffffff816efd9c R09: fffff52000cadea1 > R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888079e16558 > R13: ffff888079e16000 R14: ffff88806a59a000 R15: dffffc0000000000 > FS: 00007f62d8f56700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f83ebdff000 CR3: 000000001a7d0000 CR4: 00000000003506f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > > If the bug is already fixed, let syzbot know by replying with: > #syz fix: exact-commit-title > > If you want syzbot to run the reproducer, reply with: > #syz test: git://repo/address.git branch-or-commit-hash > If you attach or paste a git patch, syzbot will apply it before testing. > > If you want to change bug's subsystems, reply with: > #syz set subsystems: new-subsystem > (See the list of subsystem names on the web dashboard) > > If the bug is a duplicate of another bug, reply with: > #syz dup: exact-subject-of-another-report > > If you want to undo deduplication, reply with: > #syz undup
