FYI, we noticed the below changes on git://neil.brown.name/md devel commit baadac330e414eabccc2d6ea1d426fa2e40454a7 ("VFS/namei: enable RCU-walk when following symlinks.") +-------------------------------------------------------------+------------+------------+ | | 1bda3501e0 | baadac330e | +-------------------------------------------------------------+------------+------------+ | boot_successes | 22 | 10 | | early-boot-hang | 1 | | | boot_failures | 0 | 10 | | WARNING:at_fs/dcache.c:#dentry_free() | 0 | 10 | | BUG:Bad_page_state_in_process | 0 | 1 | | BUG:unable_to_handle_kernel | 0 | 7 | | Kernel_panic-not_syncing:CRED:put_cred_rcu()sees#with_usage | 0 | 1 | | Oops | 0 | 6 | | RIP:kmem_cache_alloc | 0 | 4 | | backtrace:do_sys_open | 0 | 10 | | backtrace:SyS_open | 0 | 10 | | backtrace:do_fork | 0 | 1 | | backtrace:SyS_clone | 0 | 1 | | backtrace:user_path_at | 0 | 4 | | backtrace:SyS_faccessat | 0 | 4 | | backtrace:SyS_access | 0 | 4 | | backtrace:vfs_stat | 0 | 2 | | backtrace:SyS_newstat | 0 | 2 | | WARNING:at_kernel/module.c:#module_put() | 0 | 1 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 5 | | RIP:map_id_up | 0 | 1 | | backtrace:cp_new_stat | 0 | 1 | | backtrace:SyS_newfstat | 0 | 1 | | RIP:radix_tree_next_chunk | 0 | 1 | | backtrace:link_path_walk | 0 | 1 | | backtrace:path_init | 0 | 1 | | RIP:down_write | 0 | 1 | | general_protection_fault | 0 | 1 | | RIP:mntput_no_expire | 0 | 1 | | RIP:legitimize_mnt | 0 | 1 | | backtrace:mprotect_fixup | 0 | 1 | | backtrace:SyS_mprotect | 0 | 1 | | backtrace:do_group_exit | 0 | 1 | | backtrace:SyS_exit_group | 0 | 1 | +-------------------------------------------------------------+------------+------------+ When running xfstests, system panic with the following warning in dmesg. [ 178.642528] XFS (vdd): Quotacheck needed: Please wait. [ 178.742321] XFS (vdd): Quotacheck: Done. [ 178.766701] ------------[ cut here ]------------ [ 178.768403] WARNING: CPU: 1 PID: 385 at fs/dcache.c:274 dentry_free+0x29/0x66() [ 178.771585] Modules linked in: ipmi_watchdog ipmi_msghandler microcode acpi_cpufreq processor [ 178.775362] CPU: 1 PID: 385 Comm: setquota Not tainted 4.0.0-rc7-00076-gd06842f #1 [ 178.779048] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014 [ 178.781978] 0000000000000009 ffff88007e247c78 ffffffff81a13ec9 ffff88007828ecf8 [ 178.785243] 0000000000000000 ffff88007e247cb8 ffffffff810edd33 ffff88007e247dc8 [ 178.798083] ------------[ cut here ]------------ [ 178.798089] WARNING: CPU: 2 PID: 429 at fs/dcache.c:274 dentry_free+0x29/0x66() [ 178.798094] Modules linked in: ipmi_watchdog ipmi_msghandler microcode acpi_cpufreq processor [ 178.813557] ffffffff81213804 ffff88007e8b2180 0000000000000000 ffff88007e8b21d8 [ 178.815868] Call Trace: [ 178.816614] [] dump_stack+0x4c/0x65 [ 178.817584] [] warn_slowpath_common+0xa1/0xbb [ 178.818629] [] ? dentry_free+0x29/0x66 [ 178.819919] [] warn_slowpath_null+0x1a/0x1c [ 178.821423] [] dentry_free+0x29/0x66 [ 178.822541] [] __dentry_kill+0x1a6/0x1ae [ 178.823540] [] dput+0x1bd/0x1e7 [ 178.824472] [] path_put+0x17/0x23 [ 178.825411] [] path_openat+0x332/0x63d [ 178.826479] [] do_filp_open+0x3a/0x8a [ 178.827457] [] ? __alloc_fd+0x5f/0xf6 [ 178.828535] [] do_sys_open+0x14b/0x1da [ 178.829525] [] SyS_open+0x1e/0x20 [ 178.830459] [] system_call_fastpath+0x12/0x17 [ 178.831494] ---[ end trace ca507ea65ca0f2bf ]--- [ 178.831498] CPU: 2 PID: 429 Comm: setquota Not tainted 4.0.0-rc7-00076-gd06842f #1 Thanks, Ying Huang