On 04/19/2018 06:01 AM, Fengguang Wu wrote: > Hello, > > FYI this happens in mainline kernel 4.17.0-rc1. > It at least dates back to v4.8 . > > [ 25.697463] > [ 25.697463] Start testing find_bit() with random-filled bitmap > [ 25.736615] find_next_bit: 30203201 ns, 163965 iterations > [ 25.783266] find_next_zero_bit: 45554622 ns, 163716 iterations > [ 25.832480] find_last_bit: 48003878 ns, 163965 iterations > [ 52.050031] watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1] > [ 52.050031] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.17.0-rc1 #210 > [ 52.050031] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > 1.10.2-1 04/01/2014 > [ 52.050031] RIP: 0010:__sanitizer_cov_trace_pc+0x65/0x66: > __sanitizer_cov_trace_pc at > kernel/kcov.c:111 > [ 52.050031] RSP: 0000:ffff88000fd43e40 EFLAGS: 00000246 ORIG_RAX: > ffffffffffffff13 > [ 52.050031] RAX: 0000000000000000 RBX: 0000000000000000 RCX: > 0000000000000017 > [ 52.050031] RDX: 0000000000000000 RSI: ffff88000fd3e000 RDI: > 0000000000000002 > [ 52.050031] RBP: 0000000000050000 R08: 0000000000000008 R09: > 0000000000000000 > [ 52.050031] R10: ffff88000fd3e000 R11: 00000000222e2c32 R12: > ffffffff85565d90 > [ 52.050031] R13: 0000000000030f80 R14: 0000000000030f80 R15: > 0000000000000000 > [ 52.050031] FS: 0000000000000000(0000) GS:ffff88001f600000(0000) > knlGS:0000000000000000 > [ 52.050031] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 52.050031] CR2: 0000000000000000 CR3: 0000000003c6a000 CR4: > 00000000000006b0 > [ 52.050031] Call Trace: > [ 52.050031] find_first_bit+0x66/0x7c: > find_first_bit at > lib/find_bit.c:106 (discriminator 1) > [ 52.050031] test_find_first_bit+0x3a/0x93
I suppose test_find_first_bit() needs a little more than zero cond_resched() calls. > [ 52.050031] find_bit_test+0x84/0x173: > find_bit_test at > lib/find_bit_benchmark.c:135 > [ 52.050031] ? test_find_next_and_bit+0x9b/0x9b > [ 52.050031] do_one_initcall+0x18e/0x3df: > do_one_initcall at > init/main.c:883 > [ 52.050031] ? check_kcov_mode+0x5/0x37: > check_kcov_mode at > kernel/kcov.c:60 > [ 52.050031] ? __sanitizer_cov_trace_pc+0x2b/0x66: > __sanitizer_cov_trace_pc at > kernel/kcov.c:101 > [ 52.050031] ? check_kcov_mode+0x5/0x37: > check_kcov_mode at > kernel/kcov.c:60 > [ 52.050031] kernel_init_freeable+0x250/0x3a5: > do_initcall_level at > init/main.c:951 > (inlined by) do_initcalls at > init/main.c:959 > (inlined by) do_basic_setup at > init/main.c:977 > (inlined by) > kernel_init_freeable at init/main.c:1127 > [ 52.050031] ? rest_init+0x13a/0x13a: > kernel_init at init/main.c:1050 > [ 52.050031] kernel_init+0x17/0x218: > kernel_init at init/main.c:1053 > [ 52.050031] ? rest_init+0x13a/0x13a: > kernel_init at init/main.c:1050 > [ 52.050031] ret_from_fork+0x35/0x40: > ret_from_fork at > arch/x86/entry/entry_64.S:418 > [ 52.050031] Code: 1c 00 00 8b 8b 1c 1c 00 00 48 ff 05 d2 2d fd 04 48 8b 02 > 48 ff c0 48 39 c1 76 0e 48 ff 05 c8 2d fd 04 48 89 2c c2 48 89 02 5b 5d <c3> > 48 8b 0c 24 40 0f b6 d6 40 0f b6 f7 31 ff 48 ff 05 e9 2d fd > [ 52.050031] Kernel panic - not syncing: softlockup: hung tasks
