bisecting fixing commit since ffb217a13a2eaf6d5bd974fc83036a53ca69f1e2 building syzkaller on 7bdd8b2c56b883af3e65b261cd7c942104dc2ecc testing commit ffb217a13a2eaf6d5bd974fc83036a53ca69f1e2 compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: 1203b7dd2650379509569b54d3b0e463316c647e279c9dd3f5b8b2dab62cf6db all runs: crashed: INFO: task hung in chown_common testing current HEAD 6bfb56e93bcef41859c2d5ab234ffd80b691be35 testing commit 6bfb56e93bcef41859c2d5ab234ffd80b691be35 compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: 58f2aa0e24094c490aa649cb3923ac74fd9a70fe642beeab941b7011acb63084 run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: task hung in chown_common run #2: crashed: INFO: task hung in chown_common run #3: crashed: INFO: task hung in chown_common run #4: crashed: INFO: task hung in chown_common run #5: crashed: INFO: task hung in chown_common run #6: crashed: INFO: task hung in chown_common run #7: boot failed: INFO: task hung in add_early_randomness run #8: boot failed: INFO: task hung in add_early_randomness run #9: boot failed: INFO: task hung in add_early_randomness revisions tested: 2, total time: 30m44.478506919s (build: 12m58.369324488s, test: 17m0.781469384s) the crash still happens on HEAD commit msg: cert host tools: Stop complaining about deprecated OpenSSL functions crash: INFO: task hung in chown_common INFO: task syz-executor.3:4250 blocked for more than 143 seconds. Not tainted 5.19.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.3 state:D stack:29824 pid: 4250 ppid: 4073 flags:0x00000004 Call Trace: context_switch kernel/sched/core.c:5116 [inline] __schedule+0x9cd/0x4af0 kernel/sched/core.c:6428 schedule+0xd2/0x1f0 kernel/sched/core.c:6500 rwsem_down_write_slowpath+0x68a/0x11a0 kernel/locking/rwsem.c:1172 __down_write_common kernel/locking/rwsem.c:1287 [inline] __down_write_common kernel/locking/rwsem.c:1284 [inline] __down_write kernel/locking/rwsem.c:1296 [inline] down_write+0x135/0x150 kernel/locking/rwsem.c:1543 inode_lock include/linux/fs.h:741 [inline] chown_common+0x32b/0x5e0 fs/open.c:701 do_fchownat+0xcf/0x140 fs/open.c:735 __do_sys_chown fs/open.c:755 [inline] __se_sys_chown fs/open.c:753 [inline] __x64_sys_chown+0x72/0xb0 fs/open.c:753 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f48e1689049 RSP: 002b:00007f48e2844168 EFLAGS: 00000246 ORIG_RAX: 000000000000005c RAX: ffffffffffffffda RBX: 00007f48e179c030 RCX: 00007f48e1689049 RDX: 000000000000ee00 RSI: 000000000000ee00 RDI: 0000000020000040 RBP: 00007f48e16e308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffdbf7d960f R14: 00007f48e2844300 R15: 0000000000022000 INFO: task syz-executor.5:4249 blocked for more than 144 seconds. Not tainted 5.19.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.5 state:D stack:29824 pid: 4249 ppid: 4078 flags:0x00000004 Call Trace: context_switch kernel/sched/core.c:5116 [inline] __schedule+0x9cd/0x4af0 kernel/sched/core.c:6428 schedule+0xd2/0x1f0 kernel/sched/core.c:6500 rwsem_down_write_slowpath+0x68a/0x11a0 kernel/locking/rwsem.c:1172 __down_write_common kernel/locking/rwsem.c:1287 [inline] __down_write_common kernel/locking/rwsem.c:1284 [inline] __down_write kernel/locking/rwsem.c:1296 [inline] down_write+0x135/0x150 kernel/locking/rwsem.c:1543 inode_lock include/linux/fs.h:741 [inline] chown_common+0x32b/0x5e0 fs/open.c:701 do_fchownat+0xcf/0x140 fs/open.c:735 __do_sys_chown fs/open.c:755 [inline] __se_sys_chown fs/open.c:753 [inline] __x64_sys_chown+0x72/0xb0 fs/open.c:753 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f23b6c89049 RSP: 002b:00007f23b7dd6168 EFLAGS: 00000246 ORIG_RAX: 000000000000005c RAX: ffffffffffffffda RBX: 00007f23b6d9c030 RCX: 00007f23b6c89049 RDX: 000000000000ee00 RSI: 000000000000ee00 RDI: 0000000020000040 RBP: 00007f23b6ce308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff21c98e3f R14: 00007f23b7dd6300 R15: 0000000000022000 INFO: task syz-executor.1:4251 blocked for more than 145 seconds. Not tainted 5.19.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.1 state:D stack:29824 pid: 4251 ppid: 4069 flags:0x00000004 Call Trace: context_switch kernel/sched/core.c:5116 [inline] __schedule+0x9cd/0x4af0 kernel/sched/core.c:6428 schedule+0xd2/0x1f0 kernel/sched/core.c:6500 rwsem_down_write_slowpath+0x68a/0x11a0 kernel/locking/rwsem.c:1172 __down_write_common kernel/locking/rwsem.c:1287 [inline] __down_write_common kernel/locking/rwsem.c:1284 [inline] __down_write kernel/locking/rwsem.c:1296 [inline] down_write+0x135/0x150 kernel/locking/rwsem.c:1543 inode_lock include/linux/fs.h:741 [inline] chown_common+0x32b/0x5e0 fs/open.c:701 do_fchownat+0xcf/0x140 fs/open.c:735 __do_sys_chown fs/open.c:755 [inline] __se_sys_chown fs/open.c:753 [inline] __x64_sys_chown+0x72/0xb0 fs/open.c:753 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7fc57d089049 RSP: 002b:00007fc57c7fe168 EFLAGS: 00000246 ORIG_RAX: 000000000000005c RAX: ffffffffffffffda RBX: 00007fc57d19c030 RCX: 00007fc57d089049 RDX: 000000000000ee00 RSI: 000000000000ee00 RDI: 0000000020000040 RBP: 00007fc57d0e308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc223efc7f R14: 00007fc57c7fe300 R15: 0000000000022000 INFO: task syz-executor.2:4252 blocked for more than 146 seconds. Not tainted 5.19.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.2 state:D stack:29824 pid: 4252 ppid: 4076 flags:0x00000004 Call Trace: context_switch kernel/sched/core.c:5116 [inline] __schedule+0x9cd/0x4af0 kernel/sched/core.c:6428 schedule+0xd2/0x1f0 kernel/sched/core.c:6500 rwsem_down_write_slowpath+0x68a/0x11a0 kernel/locking/rwsem.c:1172 __down_write_common kernel/locking/rwsem.c:1287 [inline] __down_write_common kernel/locking/rwsem.c:1284 [inline] __down_write kernel/locking/rwsem.c:1296 [inline] down_write+0x135/0x150 kernel/locking/rwsem.c:1543 inode_lock include/linux/fs.h:741 [inline] chown_common+0x32b/0x5e0 fs/open.c:701 do_fchownat+0xcf/0x140 fs/open.c:735 __do_sys_chown fs/open.c:755 [inline] __se_sys_chown fs/open.c:753 [inline] __x64_sys_chown+0x72/0xb0 fs/open.c:753 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7feb65c89049 RSP: 002b:00007feb653fe168 EFLAGS: 00000246 ORIG_RAX: 000000000000005c RAX: ffffffffffffffda RBX: 00007feb65d9c030 RCX: 00007feb65c89049 RDX: 000000000000ee00 RSI: 000000000000ee00 RDI: 0000000020000040 RBP: 00007feb65ce308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffffff66cdf R14: 00007feb653fe300 R15: 0000000000022000 INFO: task syz-executor.0:4248 blocked for more than 147 seconds. Not tainted 5.19.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.0 state:D stack:29824 pid: 4248 ppid: 4075 flags:0x00000004 Call Trace: context_switch kernel/sched/core.c:5116 [inline] __schedule+0x9cd/0x4af0 kernel/sched/core.c:6428 schedule+0xd2/0x1f0 kernel/sched/core.c:6500 rwsem_down_write_slowpath+0x68a/0x11a0 kernel/locking/rwsem.c:1172 __down_write_common kernel/locking/rwsem.c:1287 [inline] __down_write_common kernel/locking/rwsem.c:1284 [inline] __down_write kernel/locking/rwsem.c:1296 [inline] down_write+0x135/0x150 kernel/locking/rwsem.c:1543 inode_lock include/linux/fs.h:741 [inline] chown_common+0x32b/0x5e0 fs/open.c:701 do_fchownat+0xcf/0x140 fs/open.c:735 __do_sys_chown fs/open.c:755 [inline] __se_sys_chown fs/open.c:753 [inline] __x64_sys_chown+0x72/0xb0 fs/open.c:753 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f9b10c89049 RSP: 002b:00007f9b11d34168 EFLAGS: 00000246 ORIG_RAX: 000000000000005c RAX: ffffffffffffffda RBX: 00007f9b10d9c030 RCX: 00007f9b10c89049 RDX: 000000000000ee00 RSI: 000000000000ee00 RDI: 0000000020000040 RBP: 00007f9b10ce308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffed98762ef R14: 00007f9b11d34300 R15: 0000000000022000 INFO: task syz-executor.4:4255 blocked for more than 148 seconds. Not tainted 5.19.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.4 state:D stack:29824 pid: 4255 ppid: 4135 flags:0x00000004 Call Trace: context_switch kernel/sched/core.c:5116 [inline] __schedule+0x9cd/0x4af0 kernel/sched/core.c:6428 schedule+0xd2/0x1f0 kernel/sched/core.c:6500 rwsem_down_write_slowpath+0x68a/0x11a0 kernel/locking/rwsem.c:1172 __down_write_common kernel/locking/rwsem.c:1287 [inline] __down_write_common kernel/locking/rwsem.c:1284 [inline] __down_write kernel/locking/rwsem.c:1296 [inline] down_write+0x135/0x150 kernel/locking/rwsem.c:1543 inode_lock include/linux/fs.h:741 [inline] chown_common+0x32b/0x5e0 fs/open.c:701 do_fchownat+0xcf/0x140 fs/open.c:735 __do_sys_chown fs/open.c:755 [inline] __se_sys_chown fs/open.c:753 [inline] __x64_sys_chown+0x72/0xb0 fs/open.c:753 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7ff1bdc89049 RSP: 002b:00007ff1bd3dd168 EFLAGS: 00000246 ORIG_RAX: 000000000000005c RAX: ffffffffffffffda RBX: 00007ff1bdd9c030 RCX: 00007ff1bdc89049 RDX: 000000000000ee00 RSI: 000000000000ee00 RDI: 0000000020000040 RBP: 00007ff1bdce308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffcc6fd2b9f R14: 00007ff1bd3dd300 R15: 0000000000022000 Showing all locks held in the system: 1 lock held by khungtaskd/29: #0: ffffffff8ad7b620 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6491 1 lock held by hwrng/755: #0: ffffffff8b7b2d48 (reading_mutex){+.+.}-{3:3}, at: hwrng_fillfn+0xbb/0x250 drivers/char/hw_random/core.c:503 2 locks held by getty/3285: #0: ffff88807e4d8098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x1f/0x70 drivers/tty/tty_ldisc.c:244 #1: ffffc900028d62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xb14/0x1040 drivers/tty/n_tty.c:2124 2 locks held by syz-executor.3/4243: 2 locks held by syz-executor.3/4250: #0: ffff88806d5c4460 (sb_writers#14){.+.+}-{0:0}, at: do_fchownat+0xb8/0x140 fs/open.c:732 #1: ffff88806eaf2460 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: inode_lock include/linux/fs.h:741 [inline] #1: ffff88806eaf2460 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: chown_common+0x32b/0x5e0 fs/open.c:701 2 locks held by syz-executor.5/4241: 2 locks held by syz-executor.5/4249: #0: ffff88806fcca460 (sb_writers#14){.+.+}-{0:0}, at: do_fchownat+0xb8/0x140 fs/open.c:732 #1: ffff88806b0e1e88 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: inode_lock include/linux/fs.h:741 [inline] #1: ffff88806b0e1e88 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: chown_common+0x32b/0x5e0 fs/open.c:701 2 locks held by syz-executor.1/4238: 2 locks held by syz-executor.1/4251: #0: ffff888024684460 (sb_writers#14){.+.+}-{0:0}, at: do_fchownat+0xb8/0x140 fs/open.c:732 #1: ffff88806eaf3010 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: inode_lock include/linux/fs.h:741 [inline] #1: ffff88806eaf3010 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: chown_common+0x32b/0x5e0 fs/open.c:701 2 locks held by syz-executor.2/4240: 2 locks held by syz-executor.2/4252: #0: ffff88807cefe460 (sb_writers#14){.+.+}-{0:0}, at: do_fchownat+0xb8/0x140 fs/open.c:732 #1: ffff88806eaf2a38 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: inode_lock include/linux/fs.h:741 [inline] #1: ffff88806eaf2a38 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: chown_common+0x32b/0x5e0 fs/open.c:701 2 locks held by syz-executor.0/4242: #0: ffff888076c1f768 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x96/0xb0 fs/file.c:1036 #1: ffff88806b0e18b0 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: iterate_dir+0xad/0x6c0 fs/readdir.c:55 2 locks held by syz-executor.0/4248: #0: ffff888014dcc460 (sb_writers#14){.+.+}-{0:0}, at: do_fchownat+0xb8/0x140 fs/open.c:732 #1: ffff88806b0e18b0 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: inode_lock include/linux/fs.h:741 [inline] #1: ffff88806b0e18b0 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: chown_common+0x32b/0x5e0 fs/open.c:701 2 locks held by syz-executor.4/4254: 2 locks held by syz-executor.4/4255: #0: ffff88801e194460 (sb_writers#14){.+.+}-{0:0}, at: do_fchownat+0xb8/0x140 fs/open.c:732 #1: ffff88806b0e2460 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: inode_lock include/linux/fs.h:741 [inline] #1: ffff88806b0e2460 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: chown_common+0x32b/0x5e0 fs/open.c:701 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 29 Comm: khungtaskd Not tainted 5.19.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x57/0x7d lib/dump_stack.c:106 nmi_cpu_backtrace.cold+0x30/0xc0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x18f/0x1d0 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline] watchdog+0x891/0xc20 kernel/hung_task.c:378 kthread+0x299/0x340 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 4241 Comm: syz-executor.5 Not tainted 5.19.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:memset_erms+0x9/0x10 arch/x86/lib/memset_64.S:64 Code: c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 aa 4c 89 c8 c3 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01 RSP: 0018:ffffc900031ef850 EFLAGS: 00010246 RAX: ffff888062040000 RBX: 0000000000020000 RCX: 000000000001c1c0 RDX: 0000000000020000 RSI: 0000000000000000 RDI: ffff888062043e40 RBP: ffff8880725bf140 R08: 00000000edfd8dc0 R09: ffff888062040000 RBP: ffff8880725bf140 R08: 00000000edfd8dc0 R09: ffff888062040000 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000c40 R14: 0000000000000c40 R15: 0000000000000001 FS: 00007f23b7df7700(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055e266b36e18 CR3: 000000006ad10000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: slab_post_alloc_hook mm/slab.h:752 [inline] slab_alloc_node mm/slub.c:3214 [inline] slab_alloc mm/slub.c:3222 [inline] __kmem_cache_alloc_lru mm/slub.c:3229 [inline] kmem_cache_alloc+0x227/0x3b0 mm/slub.c:3239 p9_fcall_init+0x10b/0x200 net/9p/client.c:225 p9_tag_alloc net/9p/client.c:273 [inline] p9_client_prepare_req.part.0+0x82/0xa60 net/9p/client.c:697 p9_client_prepare_req net/9p/client.c:694 [inline] p9_client_rpc+0x177/0xe70 net/9p/client.c:734 p9_client_read_once+0x1f2/0x580 net/9p/client.c:1602 p9_client_read+0xf4/0x150 net/9p/client.c:1561 v9fs_dir_readdir+0x41f/0x620 fs/9p/vfs_dir.c:113 iterate_dir+0x47b/0x6c0 fs/readdir.c:65 __do_sys_getdents64 fs/readdir.c:369 [inline] __se_sys_getdents64 fs/readdir.c:354 [inline] __x64_sys_getdents64+0x124/0x240 fs/readdir.c:354 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f23b6c89049 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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:00007f23b7df7168 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9 RAX: ffffffffffffffda RBX: 00007f23b6d9bf60 RCX: 00007f23b6c89049 RDX: 0000000000000034 RSI: 0000000000000000 RDI: 0000000000000010 RBP: 00007f23b6ce308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff21c98e3f R14: 00007f23b7df7300 R15: 0000000000022000 ---------------- Code disassembly (best guess): 0: c1 e9 03 shr $0x3,%ecx 3: 40 0f b6 f6 movzbl %sil,%esi 7: 48 b8 01 01 01 01 01 movabs $0x101010101010101,%rax e: 01 01 01 11: 48 0f af c6 imul %rsi,%rax 15: f3 48 ab rep stos %rax,%es:(%rdi) 18: 89 d1 mov %edx,%ecx 1a: f3 aa rep stos %al,%es:(%rdi) 1c: 4c 89 c8 mov %r9,%rax 1f: c3 retq 20: 90 nop 21: 49 89 f9 mov %rdi,%r9 24: 40 88 f0 mov %sil,%al 27: 48 89 d1 mov %rdx,%rcx * 2a: f3 aa rep stos %al,%es:(%rdi) <-- trapping instruction 2c: 4c 89 c8 mov %r9,%rax 2f: c3 retq 30: 90 nop 31: 49 89 fa mov %rdi,%r10 34: 40 0f b6 ce movzbl %sil,%ecx 38: 48 rex.W 39: b8 01 01 01 01 mov $0x1010101,%eax 3e: 01 01 add %eax,(%rcx)