Greetings, 0day kernel testing robot got the below dmesg and the first bad commit is https://github.com/0day-ci/linux/commits/Uros-Bizjak/x86-asm-Use-CC_SET-C... commit 4768ab44d72e992a1f00ecca2f48e2137b3e90d0 Author: Uros Bizjak <ubizjak(a)gmail.com&gt; AuthorDate: Fri Dec 28 16:37:59 2018 +0100 Commit: 0day robot <lkp(a)intel.com&gt; CommitDate: Sat Dec 29 00:53:11 2018 +0800 x86/asm: Use CC_SET/CC_OUT in percpu_cmpxchg16b_double Use CC_SET(z)/CC_OUT(z) instead of explicit setz instruction. Using these two defines, the compiler that supports generation of condition code outputs from inline assembly flags generates one conditional jump instruction, e.g: [lea (%rdi),%rsi callq this_cpu_cmpxchg16b_emu] -- or -- [cmpxchg16b %gs:(%rdi)] jne 199764 <kmem_cache_alloc+0x44> instead of [lea (%rdi),%rsi callq this_cpu_cmpxchg16b_emu] -- or -- [cmpxchg16b %gs:(%rdi)] sete %cl test %cl,%cl je 19ae04 <kmem_cache_alloc+0x44> The complication with percpu_cmpxchg16b_double is, that the definition defaults to the call to this_cpu_cmpxchg16b_emu library function, which (depending on X86_FEATURE_CX16 flag) is later patched with real cmpxchg16b instruction. To solve this complication, the patch changes this_cpu_cmpxchg16b_emu library function to return the result in ZF flag of %rflags register, instead of %al register. Please also note that instead of popf instruction (which restores flags register to a previously saved state), the patched function uses sti, but followed by a nop, which ends the inhibition of interrupts early. The patch also introduces alternative_io_tail definition. This definition can take a tail instruction, common to all alternatives. By using this definition, it is possible to remove setz from cmpxchg16b alternatives, saved in .altinstr_replacement section, thus saving a few bytes from the binary. Signed-off-by: Uros Bizjak <ubizjak(a)gmail.com&gt; Cc: x86(a)kernel.org 00c569b567 Merge tag 'locks-v4.21-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux 4768ab44d7 x86/asm: Use CC_SET/CC_OUT in percpu_cmpxchg16b_double +----------------------------------------------------------+------------+------------+ | | 00c569b567 | 4768ab44d7 | +----------------------------------------------------------+------------+------------+ | boot_successes | 32 | 0 | | boot_failures | 1 | 11 | | BUG:kernel_hang_in_test_stage | 1 | | | WARNING:at_kernel/locking/lockdep.c:#lockdep_hardirqs_on | 0 | 11 | | RIP:lockdep_hardirqs_on | 0 | 11 | | WARNING:at_init/main.c:#start_kernel | 0 | 11 | | RIP:start_kernel | 0 | 11 | +----------------------------------------------------------+------------+------------+ [ 1.491161] sysrq: sysrq always enabled. [ 1.566498] Memory: 208392K/523768K available (12291K kernel code, 3453K rwdata, 5060K rodata, 2324K init, 24148K bss, 87324K reserved, 0K cma-reserved) [ 1.566627] random: get_random_u64 called from __kmem_cache_create+0x31/0x579 with crng_init=0 [ 1.569125] ------------[ cut here ]------------ [ 1.569154] DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)) [ 1.569287] WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:2803 lockdep_hardirqs_on+0xc5/0x19e [ 1.569321] Modules linked in: [ 1.569355] CPU: 0 PID: 0 Comm: swapper Not tainted 4.20.0-06429-g4768ab4 #1 [ 1.569382] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 1.569412] RIP: 0010:lockdep_hardirqs_on+0xc5/0x19e [ 1.569420] Code: 1f 00 85 c0 0f 84 f5 00 00 00 83 3d f0 37 68 01 00 0f 85 e8 00 00 00 48 c7 c6 22 80 1b 82 48 c7 c7 3e 16 1a 82 e8 87 d7 f9 ff <0f> 0b e9 ce 00 00 00 65 48 8b 04 25 00 4f 01 00 83 b8 04 0c 00 00 [ 1.569448] RSP: 0000:ffffffff82403d68 EFLAGS: 00010086 [ 1.569477] RAX: 0000000000000037 RBX: 0000000000000297 RCX: 0000000000000000 [ 1.569484] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff810e119a [ 1.569511] RBP: ffffffff81958451 R08: 0000000000000037 R09: ffffffff82403d00 [ 1.569518] R10: ffffffff82403d10 R11: 0000000000000000 R12: 00000000ffffffff [ 1.569545] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 1.569553] FS: 0000000000000000(0000) GS:ffff88801dc00000(0000) knlGS:0000000000000000 [ 1.569607] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.569614] CR2: ffff888004401000 CR3: 0000000002413000 CR4: 00000000000006b0 [ 1.569641] Call Trace: [ 1.569680] _raw_read_unlock_irqrestore+0x3c/0x48 [ 1.569712] get_random_u64+0x8d/0x9c [ 1.569743] __kmem_cache_create+0x31/0x579 [ 1.569776] ? create_kmalloc_cache+0x31/0xb8 [ 1.569805] create_boot_cache+0x64/0x8a [ 1.569835] create_kmalloc_cache+0x6b/0xb8 [ 1.569845] new_kmalloc_cache+0x79/0x94 [ 1.569875] create_kmalloc_caches+0x32/0x139 [ 1.569907] kmem_cache_init+0xb5/0x14e [ 1.569939] start_kernel+0x29c/0x646 [ 1.569996] secondary_startup_64+0xa4/0xb0 [ 1.570006] irq event stamp: 0 [ 1.570034] hardirqs last enabled at (0): [<0000000000000000>] (null) [ 1.570061] hardirqs last disabled at (0): [<0000000000000000>] (null) [ 1.570067] softirqs last enabled at (0): [<0000000000000000>] (null) [ 1.570094] softirqs last disabled at (0): [<0000000000000000>] (null) # HH:MM RESULT GOOD BAD GOOD_BUT_DIRTY DIRTY_NOT_BAD git bisect start 094cf30b8e2a1767b15a0646e58ce27ad3daff6f 8fe28cb58bcb235034b64cbbb7550a8a43fd88be -- git bisect bad f488ec5a70fea534f8573d4bb603a1fa2c668354 # 21:29 B 0 6 21 0 Merge 'linux-review/Alexander-Shiyan/gpu-ipu-v3-Fix-i-MX51-CSI-control-registers-offset/20181221-022057' into devel-hourly-2018122903 git bisect bad 7591f9794175009a64c07c661818b421ac0cd168 # 21:47 B 0 5 20 0 Merge 'linux-review/Ivan-Mironov/scsi-sd-Fix-cache_type_store/20181223-155445' into devel-hourly-2018122903 git bisect bad 560923dad07aa030470cbca0bb97b5e092ea7417 # 22:01 B 0 9 24 0 Merge 'linux-review/Miroslav-Benes/ring-buffer-Remove-unused-function-ring_buffer_page_len/20181228-214004' into devel-hourly-2018122903 git bisect good 1ba622a971846988d35988206b6a00659cd23ffe # 22:21 G 11 0 11 11 Merge 'kemi/rwsem_regression_debug' into devel-hourly-2018122903 git bisect bad 2366c2d9c80bb478e5df437de532b582256ee28d # 22:35 B 0 11 26 0 Merge 'linux-review/Lorenzo-Bianconi/mt76-mac-minor-optimizations-in-mt76x02_mac_tx_rate_val/20181228-180739' into devel-hourly-2018122903 git bisect good 1316c771fe984971f7f50bbabc562121651aec70 # 22:53 G 10 0 10 10 Merge 'linux-review/Yangtao-Li/csky-fix-refcount-leak-in-setup_smp/20181228-003905' into devel-hourly-2018122903 git bisect good 84473d4f2a5018c7dfcde97156f4c3b699216b65 # 23:10 G 11 0 11 11 Merge 'linux-review/Aditya-Pakki/net-phy-Add-a-return-value-check-on-bus-write/20181227-041720' into devel-hourly-2018122903 git bisect good 359a221175533a2335060fab7b54ca517508b304 # 23:32 G 11 0 11 11 Merge 'linux-review/Kangjie-Lu/net-marvell-fix-a-missing-check-of-acpi_match_device/20181226-194212' into devel-hourly-2018122903 git bisect bad 7188e3902d391c8933485d61428fdd9ec86d58a0 # 23:49 B 0 10 25 0 Merge 'linux-review/Uros-Bizjak/x86-asm-Use-CC_SET-CC_OUT-in-percpu_cmpxchg16b_double/20181229-005310' into devel-hourly-2018122903 git bisect good 0a95d7a1d68cd9b44a3f7e038ee52bad3ae865c6 # 00:04 G 11 0 11 11 Merge 'andersson-remoteproc/for-next' into devel-hourly-2018122903 git bisect bad 4768ab44d72e992a1f00ecca2f48e2137b3e90d0 # 00:19 B 0 3 18 0 x86/asm: Use CC_SET/CC_OUT in percpu_cmpxchg16b_double # first bad commit: [4768ab44d72e992a1f00ecca2f48e2137b3e90d0] x86/asm: Use CC_SET/CC_OUT in percpu_cmpxchg16b_double git bisect good 00c569b567c7f1f0da6162868fd02a9f29411805 # 00:50 G 32 0 0 0 Merge tag 'locks-v4.21-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux # extra tests with debug options git bisect bad 4768ab44d72e992a1f00ecca2f48e2137b3e90d0 # 01:06 B 0 10 25 0 x86/asm: Use CC_SET/CC_OUT in percpu_cmpxchg16b_double # extra tests on HEAD of linux-devel/devel-hourly-2018122903 git bisect bad 094cf30b8e2a1767b15a0646e58ce27ad3daff6f # 01:07 B 0 343 361 0 0day head guard for 'devel-hourly-2018122903' # extra tests on tree/branch linux-review/Uros-Bizjak/x86-asm-Use-CC_SET-CC_OUT-in-percpu_cmpxchg16b_double/20181229-005310 git bisect bad 4768ab44d72e992a1f00ecca2f48e2137b3e90d0 # 01:10 B 0 11 26 0 x86/asm: Use CC_SET/CC_OUT in percpu_cmpxchg16b_double # extra tests with first bad commit reverted git bisect good 3fae91c5f623ad6f0118bc695733931861787317 # 01:43 G 11 0 1 1 Revert "x86/asm: Use CC_SET/CC_OUT in percpu_cmpxchg16b_double" --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/lkp Intel Corporation