FYI, we noticed the following commit (built with gcc-7): commit: 83f86f39191e05612725cdfa0f9718e2c077cee6 ("proc: Use a list of inodes to flush from proc") https://github.com/0day-ci/linux/commits/Eric-W-Biederman/proc-Dentry-flushing-without-proc_mnt/20200222-080739 in testcase: boot on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 8G caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +---------------------------------------------+------------+------------+ | | 789fb5277a | 83f86f3919 | +---------------------------------------------+------------+------------+ | boot_successes | 12 | 0 | | boot_failures | 0 | 12 | | BUG:kernel_NULL_pointer_dereference,address | 0 | 8 | | Oops:#[##] | 0 | 10 | | RIP:proc_invalidate_siblings_dcache | 0 | 9 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 12 | | general_protection_fault:#[##] | 0 | 3 | | BUG:unable_to_handle_page_fault_for_address | 0 | 4 | | RIP:proc_pid_make_inode | 0 | 3 | +---------------------------------------------+------------+------------+ If you fix the issue, kindly add following tag Reported-by: kernel test robot [ 9.506457] BUG: kernel NULL pointer dereference, address: 0000000000000009 [ 9.507980] #PF: supervisor write access in kernel mode [ 9.507981] #PF: error_code(0x0002) - not-present page [ 9.507986] Oops: 0002 [#1] SMP PTI [ 9.507989] CPU: 1 PID: 1797 Comm: systemd-cgroups Not tainted 5.5.0-rc6-00054-g83f86f39191e0 #1 [ 9.507990] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 [ 9.508006] RIP: 0010:proc_pid_make_inode+0xad/0xea [ 9.508008] Code: 3a 48 8d 78 30 e8 1e 4a 79 00 49 8b 44 24 28 49 8d 4c 24 28 48 8d 53 e8 48 89 4b f0 48 89 43 e8 48 85 c0 49 89 54 24 28 74 04 <48> 89 50 08 41 c6 44 24 30 00 65 ff 0d 90 97 dc 7e 48 8d 4b 08 48 [ 9.508009] RSP: 0000:ffffc90000123b78 EFLAGS: 00010202 [ 9.508011] RAX: 0000000000000001 RBX: ffff88820a4ab238 RCX: ffff88820b22c428 [ 9.508013] RDX: ffff88820a4ab220 RSI: ffffc90000123b5c RDI: ffff88820b22c430 [ 9.508014] RBP: ffffc90000123ba0 R08: ffff88823fd2fb00 R09: ffff88820a447bb0 [ 9.508014] R10: 0000000000000000 R11: ffffffff8224d608 R12: ffff88820b22c400 [ 9.508016] R13: 0000000000004000 R14: ffff88820b248000 R15: ffffc90000123e00 [ 9.508018] FS: 0000000000000000(0000) GS:ffff88823fd00000(0063) knlGS:00000000f7964f40 [ 9.508022] CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 [ 9.509959] random: fast init done [ 9.510349] CR2: 0000000000000009 CR3: 000000020ad06000 CR4: 00000000000406e0 [ 9.552943] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 9.552944] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 9.552947] Call Trace: [ 9.552993] proc_pid_instantiate+0x1d/0x80 [ 9.552996] proc_pid_lookup+0x65/0x79 [ 9.552999] proc_root_lookup+0x1d/0x3a [ 9.553015] __lookup_slow+0xbe/0x100 [ 9.553026] walk_component+0xa3/0x12b [ 9.553031] link_path_walk+0x10e/0x45d [ 9.553034] ? path_init+0xfc/0x265 [ 9.553036] path_openat+0x18d/0xa97 [ 9.553047] ? xas_find+0x92/0x107 [ 9.553057] ? filemap_map_pages+0x237/0x24b [ 9.553059] do_filp_open+0x5c/0xc6 [ 9.553066] ? simple_attr_release+0x14/0x14 [ 9.553070] ? slab_pre_alloc_hook+0x35/0x61 [ 9.553074] ? kmem_cache_alloc+0xd5/0x159 [ 9.553079] ? do_sys_open+0x71/0xea [ 9.553081] do_sys_open+0x71/0xea [ 9.553086] do_int80_syscall_32+0x50/0x5d [ 9.553103] entry_INT80_compat+0x82/0x90 [ 9.553116] Modules linked in: [ 9.553121] CR2: 0000000000000009 [ 9.553128] ---[ end trace 71dcc8bdc10fba6c ]--- To reproduce: # build kernel cd linux cp config-5.5.0-rc6-00054-g83f86f39191e0 .config make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 olddefconfig prepare modules_prepare bzImage git clone https://github.com/intel/lkp-tests.git cd lkp-tests bin/lkp qemu -k job-script # job-script is attached in this email Thanks, lkp