file open
#0 ext4_file_open (inode=0xffff88001def3bf8, filp=0xffff88001dbe1700) at ../fs/ext4/file.c:366
#1 0xffffffff81234a4f in do_dentry_open (f=0xffff88001dbe1700, inode=0xffff88001def3bf8, open=<optimised out>, cred=0xffff88001d4e9480) at ../fs/open.c:749
#2 0xffffffff81235f8e in vfs_open (path=0xffff88001def3bf8, file=0xffff88001dbe1700, cred=<optimised out>) at ../fs/open.c:862
#3 0xffffffff81247d9c in do_last (opened=<optimised out>, op=<optimised out>, file=<optimised out>, nd=<optimised out>) at ../fs/namei.c:3379
#4 path_openat (nd=0xffffc900007ffdc0, op=0xffffc900007ffef4, flags=<optimised out>) at ../fs/namei.c:3520
#5 0xffffffff8124a1d9 in do_filp_open (dfd=<optimised out>, pathname=<optimised out>, op=0xffffc900007ffef4) at ../fs/namei.c:3555
#6 0xffffffff81236394 in do_sys_open (dfd=-100, filename=<optimised out>, flags=<optimised out>, mode=<optimised out>) at ../fs/open.c:1055
#7 0xffffffff8123649e in SYSC_open (mode=<optimised out>, flags=<optimised out>, filename=<optimised out>) at ../fs/open.c:1073
#8 SyS_open (filename=<optimised out>, flags=<optimised out>, mode=<optimised out>) at ../fs/open.c:1068
#9 0xffffffff818aaffb in entry_SYSCALL_64 () at ../arch/x86/entry/entry_64.S:203