On Wed, Jan 01, 2020 at 12:45:11PM -0800, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: bf8d1cd4 Merge tag 'scsi-fixes' of git://git.kernel.org/pu.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=11b80869e00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=ed9d672709340e35 > dashboard link: https://syzkaller.appspot.com/bug?extid=44c32606d8669fb0d45c > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=137e2615e00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11306971e00000 > > The bug was bisected to: > > commit 6dc4f100c175dd0511ae8674786e7c9006cdfbfa > Author: Ming Lei <ming.lei@xxxxxxxxxx> > Date: Fri Feb 15 11:13:19 2019 +0000 > > block: allow bio_for_each_segment_all() to iterate over multi-page bvec > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=130c5e49e00000 > final crash: https://syzkaller.appspot.com/x/report.txt?x=108c5e49e00000 > console output: https://syzkaller.appspot.com/x/log.txt?x=170c5e49e00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+44c32606d8669fb0d45c@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: 6dc4f100c175 ("block: allow bio_for_each_segment_all() to iterate > over multi-page bvec") > > INFO: task syz-executor072:10629 blocked for more than 143 seconds. > Not tainted 5.5.0-rc3-syzkaller #0 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > syz-executor072 D25264 10629 10066 0x00004004 > Call Trace: > context_switch kernel/sched/core.c:3385 [inline] > __schedule+0x934/0x1f90 kernel/sched/core.c:4081 > schedule+0xdc/0x2b0 kernel/sched/core.c:4155 > io_schedule+0x1c/0x70 kernel/sched/core.c:5799 > wait_on_page_bit_common mm/filemap.c:1175 [inline] > wait_on_page_bit+0x27c/0xa60 mm/filemap.c:1224 > wait_on_page_writeback+0x1b2/0x4f0 mm/page-writeback.c:2822 > __filemap_fdatawait_range+0x145/0x340 mm/filemap.c:526 > file_write_and_wait_range+0x1ac/0x210 mm/filemap.c:786 > __generic_file_fsync+0x79/0x200 fs/libfs.c:1000 > fat_file_fsync+0x78/0x210 fs/fat/file.c:190 > vfs_fsync_range+0x141/0x230 fs/sync.c:197 > generic_write_sync include/linux/fs.h:2856 [inline] > generic_file_write_iter+0x4ea/0x68e mm/filemap.c:3474 > call_write_iter include/linux/fs.h:1902 [inline] > do_iter_readv_writev+0x5f8/0x8f0 fs/read_write.c:693 > do_iter_write fs/read_write.c:970 [inline] > do_iter_write+0x184/0x610 fs/read_write.c:951 > vfs_iter_write+0x77/0xb0 fs/read_write.c:983 > iter_file_splice_write+0x717/0xc10 fs/splice.c:760 > do_splice_from fs/splice.c:863 [inline] > direct_splice_actor+0x123/0x190 fs/splice.c:1037 > splice_direct_to_actor+0x3b4/0xa30 fs/splice.c:992 > do_splice_direct+0x1da/0x2a0 fs/splice.c:1080 > do_sendfile+0x597/0xd00 fs/read_write.c:1464 > __do_sys_sendfile64 fs/read_write.c:1525 [inline] > __se_sys_sendfile64 fs/read_write.c:1511 [inline] > __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511 > do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x445e59 > Code: Bad RIP value. > RSP: 002b:00007ffc4bfab018 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000445e59 > RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000004 > RBP: 0000000000000000 R08: 0000000000402fe0 R09: 0000000000402fe0 > R10: 00008080fffffffe R11: 0000000000000246 R12: 0000000000000082 > R13: 0000000000402fe0 R14: 0000000000000000 R15: 0000000000000000 > > Showing all locks held in the system: > 1 lock held by khungtaskd/1116: > #0: ffffffff899a5680 (rcu_read_lock){....}, at: > debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334 > 1 lock held by rs:main Q:Reg/9913: > #0: ffff8880ae937358 (&rq->lock){-.-.}, at: newidle_balance+0xa28/0xe80 > kernel/sched/fair.c:10177 > 1 lock held by rsyslogd/9915: > #0: ffff888087f713e0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 > fs/file.c:801 > 2 locks held by getty/10037: > #0: ffff8880a2d26090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 > drivers/tty/tty_ldsem.c:340 > #1: ffffc900018132e0 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 > 2 locks held by getty/10038: > #0: ffff88809f419090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 > drivers/tty/tty_ldsem.c:340 > #1: ffffc900018932e0 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 > 2 locks held by getty/10039: > #0: ffff8880a2725090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 > drivers/tty/tty_ldsem.c:340 > #1: ffffc900018732e0 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 > 2 locks held by getty/10040: > #0: ffff8880966a2090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 > drivers/tty/tty_ldsem.c:340 > #1: ffffc900018832e0 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 > 2 locks held by getty/10041: > #0: ffff88809e168090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 > drivers/tty/tty_ldsem.c:340 > #1: ffffc900017f32e0 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 > 2 locks held by getty/10042: > #0: ffff8880a7c45090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 > drivers/tty/tty_ldsem.c:340 > #1: ffffc900018332e0 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 > 2 locks held by getty/10043: > #0: ffff88809958e090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 > drivers/tty/tty_ldsem.c:340 > #1: ffffc900011402e0 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 > 1 lock held by syz-executor072/10629: > #0: ffff88809a52a428 (sb_writers#9){.+.+}, at: file_start_write > include/linux/fs.h:2885 [inline] > #0: ffff88809a52a428 (sb_writers#9){.+.+}, at: do_sendfile+0x9b9/0xd00 > fs/read_write.c:1463 > > ============================================= > > NMI backtrace for cpu 0 > CPU: 0 PID: 1116 Comm: khungtaskd Not tainted 5.5.0-rc3-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+0x197/0x210 lib/dump_stack.c:118 > nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 > nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62 > arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 > trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] > check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] > watchdog+0xb11/0x10c0 kernel/hung_task.c:289 > kthread+0x361/0x430 kernel/kthread.c:255 > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 > Sending NMI from CPU 0 to CPUs 1: > NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0xe/0x10 > arch/x86/include/asm/irqflags.h:60 > It has been addressed by: https://lore.kernel.org/linux-block/bcc25948-7250-7c82-a764-91ce4c938185@xxxxxxxxx/T/#t Thanks, Ming
