From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f195.google.com ([209.85.192.195]:39428 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752255AbeD3RzY (ORCPT ); Mon, 30 Apr 2018 13:55:24 -0400 Received: by mail-pf0-f195.google.com with SMTP id z9so7312415pfe.6 for ; Mon, 30 Apr 2018 10:55:24 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <0000000000006de361056b146dbe@google.com> References: <0000000000006de361056b146dbe@google.com> From: Dmitry Vyukov Date: Mon, 30 Apr 2018 19:55:03 +0200 Message-ID: Subject: Re: INFO: task hung in lock_mount To: syzbot Cc: linux-fsdevel , LKML , syzkaller-bugs , Al Viro Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Mon, Apr 30, 2018 at 7:46 PM, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: a27fc14219f2 Merge branch 'parisc-4.17-3' of > git://git.kernel... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?id=5953322812964864 > kernel config: > https://syzkaller.appspot.com/x/.config?id=-5914490758943236750 > dashboard link: https://syzkaller.appspot.com/bug?extid=221d75710bde87fa0e97 > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+221d75710bde87fa0e97@syzkaller.appspotmail.com It seems this thread is in infinite loop printing: [ 643.736460] b_state=0x00000029, b_size=512 [ 643.740722] device loop0 blocksize: 4096 [ 643.744857] __find_get_block_slow() failed. block=1, b_blocknr=8 [ 643.751020] b_state=0x00000029, b_size=512 [ 643.755271] device loop0 blocksize: 4096 [ 643.759349] __find_get_block_slow() failed. block=1, b_blocknr=8 [ 643.765540] b_state=0x00000029, b_size=512 ... > __find_get_block_slow() failed. block=1, b_blocknr=8 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > b_state=0x00000029, b_size=512 > INFO: task syz-executor0:20276 blocked for more than 120 seconds. > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > Not tainted 4.17.0-rc1+ #6 > b_state=0x00000029, b_size=512 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > syz-executor0 D24704 20276 23010 0x00000004 > device loop0 blocksize: 4096 > Call Trace: > context_switch kernel/sched/core.c:2848 [inline] > __schedule+0x801/0x1e30 kernel/sched/core.c:3490 > __find_get_block_slow() failed. block=1, b_blocknr=8 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > schedule+0xef/0x430 kernel/sched/core.c:3549 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > __rwsem_down_write_failed_common+0x919/0x15d0 > kernel/locking/rwsem-xadd.c:566 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > b_state=0x00000029, b_size=512 > rwsem_down_write_failed+0xe/0x10 kernel/locking/rwsem-xadd.c:595 > device loop0 blocksize: 4096 > call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:117 > __find_get_block_slow() failed. block=1, b_blocknr=8 > __down_write arch/x86/include/asm/rwsem.h:142 [inline] > down_write+0xa2/0x120 kernel/locking/rwsem.c:72 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > b_state=0x00000029, b_size=512 > inode_lock include/linux/fs.h:713 [inline] > lock_mount+0x8c/0x2e0 fs/namespace.c:2087 > device loop0 blocksize: 4096 > do_add_mount+0x27/0x370 fs/namespace.c:2464 > __find_get_block_slow() failed. block=1, b_blocknr=8 > do_new_mount fs/namespace.c:2531 [inline] > do_mount+0x18e6/0x3070 fs/namespace.c:2847 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > ksys_mount+0x12d/0x140 fs/namespace.c:3063 > __do_sys_mount fs/namespace.c:3077 [inline] > __se_sys_mount fs/namespace.c:3074 [inline] > __x64_sys_mount+0xbe/0x150 fs/namespace.c:3074 > b_state=0x00000029, b_size=512 > do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > b_state=0x00000029, b_size=512 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x455329 > device loop0 blocksize: 4096 > RSP: 002b:00007f68cf133c68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 > RAX: ffffffffffffffda RBX: 00007f68cf1346d4 RCX: 0000000000455329 > __find_get_block_slow() failed. block=1, b_blocknr=8 > RDX: 0000000020000240 RSI: 0000000020000080 RDI: 0000000020000280 > RBP: 000000000072bf58 R08: 0000000020000040 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff > b_state=0x00000029, b_size=512 > R13: 00000000000003fb R14: 00000000006f9028 R15: 0000000000000001 > > Showing all locks held in the system: > device loop0 blocksize: 4096 > 2 locks held by khungtaskd/888: > __find_get_block_slow() failed. block=1, b_blocknr=8 > #0: 00000000a9a44477 ( > b_state=0x00000029, b_size=512 > rcu_read_lock){....}, at: check_hung_uninterruptible_tasks > kernel/hung_task.c:175 [inline] > rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 > device loop0 blocksize: 4096 > #1: 000000009ff2053f (tasklist_lock){.+.+}, at: > debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 > 2 locks held by getty/4439: > __find_get_block_slow() failed. block=1, b_blocknr=8 > #0: 00000000c9b76b9a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 > drivers/tty/tty_ldsem.c:365 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > #1: > b_state=0x00000029, b_size=512 > 000000000e5cb710 (&ldata->atomic_read_lock){+.+.} > device loop0 blocksize: 4096 > , at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 > 2 locks held by getty/4440: > __find_get_block_slow() failed. block=1, b_blocknr=8 > #0: 000000005b768cd3 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 > drivers/tty/tty_ldsem.c:365 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > #1: 00000000addaef00 ( > __find_get_block_slow() failed. block=1, b_blocknr=8 > &ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 > drivers/tty/n_tty.c:2131 > 2 locks held by getty/4441: > #0: 000000000c8a520e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 > drivers/tty/tty_ldsem.c:365 > #1: 00000000be9918f7 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 > 2 locks held by getty/4442: > #0: 0000000029e321e8 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 > drivers/tty/tty_ldsem.c:365 > #1: 00000000c3a0104f (&ldata->atomic_read_lock > b_state=0x00000029, b_size=512 > ){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 > 2 locks held by getty/4443: > device loop0 blocksize: 4096 > #0: 00000000b12d6ffd ( > __find_get_block_slow() failed. block=1, b_blocknr=8 > &tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 > drivers/tty/tty_ldsem.c:365 > #1: > b_state=0x00000029, b_size=512 > 00000000625407e7 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 > 2 locks held by getty/4444: > device loop0 blocksize: 4096 > #0: 0000000019948f4c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 > drivers/tty/tty_ldsem.c:365 > #1: > __find_get_block_slow() failed. block=1, b_blocknr=8 > 00000000071c1ff8 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 > 2 locks held by getty/4445: > b_state=0x00000029, b_size=512 > #0: 00000000fe9e0006 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 > drivers/tty/tty_ldsem.c:365 > device loop0 blocksize: 4096 > #1: 00000000a738c9c9 ( > __find_get_block_slow() failed. block=1, b_blocknr=8 > &ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 > drivers/tty/n_tty.c:2131 > 1 lock held by syz-executor0/20276: > b_state=0x00000029, b_size=512 > #0: 00000000a1afb949 (&sb->s_type->i_mutex_key#16){++++} > device loop0 blocksize: 4096 > , at: inode_lock include/linux/fs.h:713 [inline] > , at: lock_mount+0x8c/0x2e0 fs/namespace.c:2087 > 2 locks held by syz-executor0/20277: > __find_get_block_slow() failed. block=1, b_blocknr=8 > #0: 000000008134fa51 (sb_writers#14){.+.+}, at: sb_start_write > include/linux/fs.h:1550 [inline] > #0: 000000008134fa51 (sb_writers#14){.+.+}, at: mnt_want_write+0x3f/0xc0 > fs/namespace.c:386 > #1: 00000000a1afb949 > b_state=0x00000029, b_size=512 > device loop0 blocksize: 4096 > (&sb->s_type->i_mutex_key#16/1 > __find_get_block_slow() failed. block=1, b_blocknr=8 > ){+.+.}, at: inode_lock_nested include/linux/fs.h:748 [inline] > ){+.+.}, at: filename_create+0x1aa/0x5a0 fs/namei.c:3606 > 1 lock held by syz-executor0/20279: > #0: > b_state=0x00000029, b_size=512 > 00000000a1afb949 (&sb->s_type->i_mutex_key#16){++++}, at: inode_lock > include/linux/fs.h:713 [inline] > 00000000a1afb949 (&sb->s_type->i_mutex_key#16){++++}, at: > lock_mount+0x8c/0x2e0 fs/namespace.c:2087 > > device loop0 blocksize: 4096 > ============================================= > > NMI backtrace for cpu 0 > CPU: 0 PID: 888 Comm: khungtaskd Not tainted 4.17.0-rc1+ #6 > __find_get_block_slow() failed. block=1, b_blocknr=8 > 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+0x1b9/0x294 lib/dump_stack.c:113 > nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103 > b_state=0x00000029, b_size=512 > nmi_trigger_cpumask_backtrace+0x151/0x192 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:138 [inline] > check_hung_task kernel/hung_task.c:132 [inline] > check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] > watchdog+0xc10/0xf60 kernel/hung_task.c:249 > device loop0 blocksize: 4096 > __find_get_block_slow() failed. block=1, b_blocknr=8 > kthread+0x345/0x410 kernel/kthread.c:238 > ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 > Sending NMI from CPU 0 to CPUs 1: > b_state=0x00000029, b_size=512 > NMI backtrace for cpu 1 > CPU: 1 PID: 20216 Comm: syz-executor0 Not tainted 4.17.0-rc1+ #6 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x1/0x20 kernel/kcov.c:187 > RSP: 0018:ffff8801db107d88 EFLAGS: 00000006 > RAX: ffff8801d11bc6c0 RBX: ffff8801db11f0c0 RCX: ffffffff816b3515 > RDX: 0000000000010000 RSI: 0000000000000003 RDI: 0000000000000003 > RBP: ffff8801db107dc0 R08: ffff8801d11bc6c0 R09: ffffed003b624b80 > R10: ffffed003b624b80 R11: ffff8801db125c03 R12: 000000ac0c601b80 > R13: 0000000000000000 R14: 0000000000000003 R15: ffff8801db125c00 > FS: 00007f68cf155700(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: ffffffffff600400 CR3: 00000001d8a72000 CR4: 00000000001406e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > > tick_program_event+0xab/0x130 kernel/time/tick-oneshot.c:48 > hrtimer_interrupt+0x2db/0x650 kernel/time/hrtimer.c:1519 > local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline] > smp_apic_timer_interrupt+0x15d/0x710 arch/x86/kernel/apic/apic.c:1050 > apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863 > > RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:783 > [inline] > RIP: 0010:console_trylock_spinning kernel/printk/printk.c:1678 [inline] > RIP: 0010:vprintk_emit+0xbd0/0xdd0 kernel/printk/printk.c:1906 > RSP: 0018:ffff88018a2df000 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 > RAX: 0000000000040000 RBX: 0000000000000200 RCX: ffffc90003ac6000 > RDX: 0000000000040000 RSI: ffffffff8160bbb7 RDI: 0000000000000246 > RBP: ffff88018a2df190 R08: ffff8801d11bcef8 R09: 0000000000000006 > R10: ffff8801d11bc6c0 R11: 0000000000000000 R12: 1ffffffff116312d > R13: 000000000000001e R14: ffffed003145be1d R15: ffffffff8a49a360 > vprintk_default+0x28/0x30 kernel/printk/printk.c:1947 > vprintk_func+0x7a/0xe7 kernel/printk/printk_safe.c:379 > printk+0x9e/0xba kernel/printk/printk.c:1980 > __find_get_block_slow fs/buffer.c:235 [inline] > __find_get_block.cold.58+0x85/0x103 fs/buffer.c:1287 > __getblk_slow fs/buffer.c:1032 [inline] > __getblk_gfp+0x2a1/0xaf0 fs/buffer.c:1313 > __bread_gfp+0x2d/0x310 fs/buffer.c:1347 > sb_bread include/linux/buffer_head.h:309 [inline] > fat__get_entry+0x594/0xa20 fs/fat/dir.c:101 > fat_get_entry fs/fat/dir.c:129 [inline] > fat_search_long+0x33b/0x15d0 fs/fat/dir.c:477 > vfat_find+0x16d/0x1a0 fs/fat/namei_vfat.c:697 > vfat_lookup+0xfc/0x6d0 fs/fat/namei_vfat.c:720 > __lookup_hash+0x12e/0x190 fs/namei.c:1505 > filename_create+0x1dd/0x5a0 fs/namei.c:3607 > user_path_create fs/namei.c:3664 [inline] > do_mkdirat+0xd2/0x2f0 fs/namei.c:3802 > __do_sys_mkdir fs/namei.c:3826 [inline] > __se_sys_mkdir fs/namei.c:3824 [inline] > __x64_sys_mkdir+0x5c/0x80 fs/namei.c:3824 > do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x455329 > RSP: 002b:00007f68cf154c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000053 > RAX: ffffffffffffffda RBX: 00007f68cf1556d4 RCX: 0000000000455329 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000080 > RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff > R13: 00000000000003eb R14: 00000000006f8ea8 R15: 0000000000000000 > Code: a6 fe ff ff 5d c3 0f 1f 40 00 55 0f b7 d6 0f b7 f7 bf 03 00 00 00 48 > 89 e5 48 8b 4d 08 e8 88 fe ff ff 5d c3 66 0f 1f 44 00 00 55 <89> f2 89 fe bf > 05 00 00 00 48 89 e5 48 8b 4d 08 e8 6a fe ff ff > INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.012 > msecs > > > --- > This bug 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@googlegroups.com. > > syzbot will keep track of this bug report. > If you forgot to add the Reported-by tag, once the fix for this bug is > merged > into any tree, please reply to this email with: > #syz fix: exact-commit-title > To mark this as a duplicate of another syzbot report, please reply with: > #syz dup: exact-subject-of-another-report > If it's a one-off invalid bug report, please reply with: > #syz invalid > Note: if the crash happens again, it will cause creation of a new bug > report. > Note: all commands must start from beginning of the line in the email body. > > -- > You received this message because you are subscribed to the Google Groups > "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to syzkaller-bugs+unsubscribe@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/syzkaller-bugs/0000000000006de361056b146dbe%40google.com. > For more options, visit https://groups.google.com/d/optout.