Greeting, FYI, we noticed the following commit (built with gcc-9): commit: 2037ab69a5cd8afe58347135010f6160ea368dd0 ("mm: Convert find_get_entry to return the head page") url: https://github.com/0day-ci/linux/commits/Matthew-Wilcox-Oracle/Return-head-pages-from-find_-_entry/20200911-023452 in testcase: trinity version: trinity-x86_64-af355e9-1_2019-12-03 with following parameters: runtime: 300s test-description: Trinity is a linux system call fuzz tester. test-url: http://codemonkey.org.uk/projects/trinity/ 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): +----------------------------------------------------------------------------+------------+------------+ | | a27ee9830b | 2037ab69a5 | +----------------------------------------------------------------------------+------------+------------+ | boot_successes | 4 | 2 | | boot_failures | 0 | 8 | | Kernel_panic-not_syncing:VFS:Unable_to_mount_root_fs_on_unknown-block(#,#) | 0 | 2 | | BUG:KASAN:null-ptr-deref_in_t | 0 | 6 | | BUG:kernel_NULL_pointer_dereference,address | 0 | 6 | | Oops:#[##] | 0 | 6 | | RIP:test_bit | 0 | 6 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 6 | +----------------------------------------------------------------------------+------------+------------+ If you fix the issue, kindly add following tag Reported-by: kernel test robot [ 162.744647] BUG: KASAN: null-ptr-deref in test_bit+0x23/0x2e [ 162.745610] Read of size 8 at addr 0000000000000000 by task trinity-c1/1847 [ 162.746669] [ 162.746984] CPU: 0 PID: 1847 Comm: trinity-c1 Not tainted 5.9.0-rc4-next-20200910-00006-g2037ab69a5cd8a #1 [ 162.748495] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 [ 162.749850] Call Trace: [ 162.750377] kasan_report+0x154/0x170 [ 162.751068] ? test_bit+0x23/0x2e [ 162.751706] check_memory_region+0x13d/0x145 [ 162.752528] test_bit+0x23/0x2e [ 162.753128] PageHuge+0x16/0x7c [ 162.753748] find_get_incore_page+0x29/0xd3 [ 162.754631] __mincore_unmapped_range+0x169/0x210 [ 162.755548] mincore_unmapped_range+0x6d/0x9d [ 162.756379] walk_pgd_range+0x736/0xa8b [ 162.757156] __walk_page_range+0xd8/0x3f9 [ 162.757935] walk_page_range+0x178/0x205 [ 162.758710] ? __walk_page_range+0x3f9/0x3f9 [ 162.759569] ? hlock_class+0x3b/0xf2 [ 162.760303] __do_sys_mincore+0x3a5/0x459 [ 162.761161] do_syscall_64+0x2e/0x68 [ 162.761861] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 162.762903] RIP: 0033:0x7f923a75f1c9 [ 162.763621] Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 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 8b 0d 97 dc 2c 00 f7 d8 64 89 01 48 [ 162.766849] RSP: 002b:00007ffc8082ed18 EFLAGS: 00000246 ORIG_RAX: 000000000000001b [ 162.768139] RAX: ffffffffffffffda RBX: 000000000000001b RCX: 00007f923a75f1c9 [ 162.769213] RDX: 00007f92371ff010 RSI: 00000000000cc000 RDI: 00007f9238b47000 [ 162.770389] RBP: 00007f923ae44000 R08: 0000000000000041 R09: fffffffff8000000 [ 162.771458] R10: 00006407736b759e R11: 0000000000000246 R12: 00007f923ae44058 [ 162.772600] R13: 00007f923ae526b0 R14: 0000000000000000 R15: 00007f923ae44000 [ 162.773757] ================================================================== [ 162.774941] Disabling lock debugging due to kernel taint [ 162.775936] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 162.777007] #PF: supervisor read access in kernel mode [ 162.777862] #PF: error_code(0x0000) - not-present page [ 162.778635] PGD 1d6103067 P4D 1d6103067 PUD 1c687e067 PMD 0 [ 162.779570] Oops: 0000 [#1] KASAN [ 162.780129] CPU: 0 PID: 1847 Comm: trinity-c1 Tainted: G B 5.9.0-rc4-next-20200910-00006-g2037ab69a5cd8a #1 [ 162.781812] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 [ 162.783297] RIP: 0010:test_bit+0x23/0x2e [ 162.784043] Code: 00 8b 43 34 5b 5d c3 48 89 f8 b9 40 00 00 00 55 48 89 f5 48 99 53 48 89 fb 48 f7 f9 48 8d 3c c6 be 08 00 00 00 e8 3d 6b 01 00 <48> 0f a3 5d 00 0f 92 c0 5b 5d c3 53 48 89 fe 48 89 fb bf 10 00 00 [ 162.787441] RSP: 0018:ffff88818d587bd0 EFLAGS: 00010286 [ 162.788425] RAX: 00000000b4610a00 RBX: 0000000000000010 RCX: ffffffff8c246fc2 [ 162.789733] RDX: fffffbfff1e79c96 RSI: 0000000000000000 RDI: ffffffff8d8a2f7b [ 162.791090] RBP: 0000000000000000 R08: fffffbfff1e79c96 R09: 0000000000000000 [ 162.792423] R10: fffffbfff1e79c96 R11: ffffffff8f3ce4ab R12: 0000000000000000 [ 162.793745] R13: ffff8881f0c076b0 R14: ffff888180f88001 R15: 0000000000000000 [ 162.795078] FS: 00007f923ae52740(0000) GS:ffffffff8e8cd000(0000) knlGS:0000000000000000 [ 162.796303] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 162.797250] CR2: 0000000000000000 CR3: 000000018f354000 CR4: 00000000000406f0 [ 162.798357] DR0: 00007f923ad2e000 DR1: 00007f9238747000 DR2: 0000000000000000 [ 162.799515] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 [ 162.800595] Call Trace: [ 162.801031] PageHuge+0x16/0x7c [ 162.801562] find_get_incore_page+0x29/0xd3 [ 162.802205] __mincore_unmapped_range+0x169/0x210 [ 162.807040] mincore_unmapped_range+0x6d/0x9d [ 162.807705] walk_pgd_range+0x736/0xa8b [ 162.808293] __walk_page_range+0xd8/0x3f9 [ 162.808906] walk_page_range+0x178/0x205 [ 162.809496] ? __walk_page_range+0x3f9/0x3f9 [ 162.810161] ? hlock_class+0x3b/0xf2 [ 162.810760] __do_sys_mincore+0x3a5/0x459 [ 162.811460] do_syscall_64+0x2e/0x68 [ 162.812052] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 162.812881] RIP: 0033:0x7f923a75f1c9 [ 162.813503] Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 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 8b 0d 97 dc 2c 00 f7 d8 64 89 01 48 [ 162.816544] RSP: 002b:00007ffc8082ed18 EFLAGS: 00000246 ORIG_RAX: 000000000000001b [ 162.817626] RAX: ffffffffffffffda RBX: 000000000000001b RCX: 00007f923a75f1c9 [ 162.818676] RDX: 00007f92371ff010 RSI: 00000000000cc000 RDI: 00007f9238b47000 [ 162.819837] RBP: 00007f923ae44000 R08: 0000000000000041 R09: fffffffff8000000 [ 162.820990] R10: 00006407736b759e R11: 0000000000000246 R12: 00007f923ae44058 [ 162.822105] R13: 00007f923ae526b0 R14: 0000000000000000 R15: 00007f923ae44000 [ 162.823282] Modules linked in: [ 162.823839] CR2: 0000000000000000 [ 162.824521] ---[ end trace 2d46de9c846249c1 ]--- To reproduce: # build kernel cd linux cp config-5.9.0-rc4-next-20200910-00006-g2037ab69a5cd8a .config make HOSTCC=gcc-9 CC=gcc-9 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