[PATCHv8 1/5] powerpc/setup : Enable boot_cpu_hwid for PPC32
Sourabh Jain
sourabhjain at linux.ibm.com
Sun Oct 15 23:43:53 PDT 2023
Hello Pingfan,
>>>>> With this patch series applied, the kdump kernel fails to boot on
>>>>> powerpc with nr_cpus=1.
>>>>>
>>>>> Console logs:
>>>>> -------------------
>>>>> [root]# echo c > /proc/sysrq-trigger
>>>>> [ 74.783235] sysrq: Trigger a crash
>>>>> [ 74.783244] Kernel panic - not syncing: sysrq triggered crash
>>>>> [ 74.783252] CPU: 58 PID: 3838 Comm: bash Kdump: loaded Not tainted
>>>>> 6.6.0-rc5pf-nr-cpus+ #3
>>>>> [ 74.783259] Hardware name: POWER10 (raw) phyp pSeries
>>>>> [ 74.783275] Call Trace:
>>>>> [ 74.783280] [c00000020f4ebac0] [c000000000ed9f38]
>>>>> dump_stack_lvl+0x6c/0x9c (unreliable)
>>>>> [ 74.783291] [c00000020f4ebaf0] [c000000000150300] panic+0x178/0x438
>>>>> [ 74.783298] [c00000020f4ebb90] [c000000000936d48]
>>>>> sysrq_handle_crash+0x28/0x30
>>>>> [ 74.783304] [c00000020f4ebbf0] [c00000000093773c]
>>>>> __handle_sysrq+0x10c/0x250
>>>>> [ 74.783309] [c00000020f4ebc90] [c000000000937fa8]
>>>>> write_sysrq_trigger+0xc8/0x168
>>>>> [ 74.783314] [c00000020f4ebcd0] [c000000000665d8c]
>>>>> proc_reg_write+0x10c/0x1b0
>>>>> [ 74.783321] [c00000020f4ebd00] [c00000000058da54]
>>>>> vfs_write+0x104/0x4b0
>>>>> [ 74.783326] [c00000020f4ebdc0] [c00000000058dfdc]
>>>>> ksys_write+0x7c/0x140
>>>>> [ 74.783331] [c00000020f4ebe10] [c000000000033a64]
>>>>> system_call_exception+0x144/0x3a0
>>>>> [ 74.783337] [c00000020f4ebe50] [c00000000000c554]
>>>>> system_call_common+0xf4/0x258
>>>>> [ 74.783343] --- interrupt: c00 at 0x7fffa0721594
>>>>> [ 74.783352] NIP: 00007fffa0721594 LR: 00007fffa0697bf4 CTR:
>>>>> 0000000000000000
>>>>> [ 74.783364] REGS: c00000020f4ebe80 TRAP: 0c00 Not tainted
>>>>> (6.6.0-rc5pf-nr-cpus+)
>>>>> [ 74.783376] MSR: 800000000280f033
>>>>> <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 28222202 XER: 00000000
>>>>> [ 74.783394] IRQMASK: 0
>>>>> [ 74.783394] GPR00: 0000000000000004 00007ffffc4b6800 00007fffa0807300
>>>>> 0000000000000001
>>>>> [ 74.783394] GPR04: 000000013549ea60 0000000000000002 0000000000000010
>>>>> 0000000000000000
>>>>> [ 74.783394] GPR08: 0000000000000000 0000000000000000 0000000000000000
>>>>> 0000000000000000
>>>>> [ 74.783394] GPR12: 0000000000000000 00007fffa0abaf70 0000000040000000
>>>>> 000000011a0f9798
>>>>> [ 74.783394] GPR16: 000000011a0f9724 000000011a097688 000000011a02ff70
>>>>> 000000011a0fd568
>>>>> [ 74.783394] GPR20: 0000000135554bf0 0000000000000001 000000011a0aa478
>>>>> 00007ffffc4b6a24
>>>>> [ 74.783394] GPR24: 00007ffffc4b6a20 000000011a0faf94 0000000000000002
>>>>> 000000013549ea60
>>>>> [ 74.783394] GPR28: 0000000000000002 00007fffa08017a0 000000013549ea60
>>>>> 0000000000000002
>>>>> [ 74.783440] NIP [00007fffa0721594] 0x7fffa0721594
>>>>> [ 74.783443] LR [00007fffa0697bf4] 0x7fffa0697bf4
>>>>> [ 74.783447] --- interrupt: c00
>>>>> I'm in purgatory
>>>>> [ 0.000000] radix-mmu: Page sizes from device-tree:
>>>>> [ 0.000000] radix-mmu: Page size shift = 12 AP=0x0
>>>>> [ 0.000000] radix-mmu: Page size shift = 16 AP=0x5
>>>>> [ 0.000000] radix-mmu: Page size shift = 21 AP=0x1
>>>>> [ 0.000000] radix-mmu: Page size shift = 30 AP=0x2
>>>>> [ 0.000000] Activating Kernel Userspace Access Prevention
>>>>> [ 0.000000] Activating Kernel Userspace Execution Prevention
>>>>> [ 0.000000] radix-mmu: Mapped 0x0000000000000000-0x0000000000010000
>>>>> with 64.0 KiB pages (exec)
>>>>> [ 0.000000] radix-mmu: Mapped 0x0000000000010000-0x0000000000200000
>>>>> with 64.0 KiB pages
>>>>> [ 0.000000] radix-mmu: Mapped 0x0000000000200000-0x0000000020000000
>>>>> with 2.00 MiB pages
>>>>> [ 0.000000] radix-mmu: Mapped 0x0000000020000000-0x0000000022600000
>>>>> with 2.00 MiB pages (exec)
>>>>> [ 0.000000] radix-mmu: Mapped 0x0000000022600000-0x0000000040000000
>>>>> with 2.00 MiB pages
>>>>> [ 0.000000] radix-mmu: Mapped 0x0000000040000000-0x0000000180000000
>>>>> with 1.00 GiB pages
>>>>> [ 0.000000] radix-mmu: Mapped 0x0000000180000000-0x00000001a0000000
>>>>> with 2.00 MiB pages
>>>>> [ 0.000000] lpar: Using radix MMU under hypervisor
>>>>> [ 0.000000] Linux version 6.6.0-rc5pf-nr-cpus+
>>>>> (root at ltcever7x0-lp1.aus.stglabs.ibm.com) (gcc (GCC) 8.5.0 20210514 (Red
>>>>> Hat 8.5.0-20), GNU ld version 2.30-123.el8) #3 SMP Mon Oct 9 11:07:
>>>>> 41 CDT 2023
>>>>> [ 0.000000] Found initrd at 0xc000000022e60000:0xc0000000248f08d8
>>>>> [ 0.000000] Hardware name: IBM,9043-MRX POWER10 (raw) 0x800200
>>>>> 0xf000006 of:IBM,FW1060.00 (NM1060_016) hv:phyp pSeries
>>>>> [ 0.000000] printk: bootconsole [udbg0] enabled
>>>>> [ 0.000000] the round shift between dt seq and the cpu logic number:
>>>>> 56
>>>>> [ 0.000000] BUG: Unable to handle kernel data access on write at
>>>>> 0xc0000001a0000000
>>>>> [ 0.000000] Faulting instruction address: 0xc000000022009c64
>>>>> [ 0.000000] Oops: Kernel access of bad area, sig: 11 [#1]
>>>>> [ 0.000000] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
>>>>> [ 0.000000] Modules linked in:
>>>>> [ 0.000000] CPU: 2 PID: 0 Comm: swapper Not tainted
>>>>> 6.6.0-rc5pf-nr-cpus+ #3
>>>>> [ 0.000000] Hardware name: POWER10 (raw) hv:phyp pSeries
>>>>> [ 0.000000] NIP: c000000022009c64 LR: c000000022009c54 CTR:
>>>>> c0000000201ff348
>>>>> [ 0.000000] REGS: c000000022aebb00 TRAP: 0300 Not tainted
>>>>> (6.6.0-rc5pf-nr-cpus+)
>>>>> [ 0.000000] MSR: 8000000000001033 <SF,ME,IR,DR,RI,LE> CR: 28222824
>>>>> XER: 00000001
>>>>> [ 0.000000] CFAR: c000000020031574 DAR: c0000001a0000000 DSISR:
>>>>> 42000000 IRQMASK: 1
>>>>> [ 0.000000] GPR00: c000000022009ba0 c000000022aebda0 c0000000213d1300
>>>>> 0000000000000004
>>>>> [ 0.000000] GPR04: 0000000000000001 c000000022aebbc0 c000000022aebbb8
>>>>> 0000000000000000
>>>>> [ 0.000000] GPR08: 0000000000000001 c00000019ffffff8 000000000000003a
>>>>> c0000000229c8a78
>>>>> [ 0.000000] GPR12: 0000000000002000 c000000022e4a800 c0000000211d34b8
>>>>> c0000000211d3aa8
>>>>> [ 0.000000] GPR16: c0000000211d75a0 c0000000211d75b0 c0000000225f3b98
>>>>> 0000000000000000
>>>>> [ 0.000000] GPR20: 0000000000000001 0000000000000001 0000000000000001
>>>>> 0000000000000001
>>>>> [ 0.000000] GPR24: 0000000000000008 0000000000000000 0000000000000001
>>>>> c00000019ffffdc0
>>>>> [ 0.000000] GPR28: 0000000000000002 c000000022b368e0 c000000022aebe08
>>>>> 0000000000000008
>>>>> [ 0.000000] NIP [c000000022009c64] smp_setup_cpu_maps+0x420/0x724
>>>>> [ 0.000000] LR [c000000022009c54] smp_setup_cpu_maps+0x410/0x724
>>>>> [ 0.000000] Call Trace:
>>>>> [ 0.000000] [c000000022aebda0] [c000000022009ba0]
>>>>> smp_setup_cpu_maps+0x35c/0x724 (unreliable)
>>>>> [ 0.000000] [c000000022aebeb0] [c00000002200a19c]
>>>>> setup_arch+0x1b8/0x54c
>>>>> [ 0.000000] [c000000022aebf30] [c000000022003f88]
>>>>> start_kernel+0xb0/0x768
>>>>> [ 0.000000] [c000000022aebfe0] [c00000002000d888]
>>>>> start_here_common+0x1c/0x20
>>>>> [ 0.000000] Code: 3929ffff 7f89e040 409c002c 7ec4b378 7f83e378
>>>>> 4a027939 7f83e378 4a0278e5 e95b0018 3d22017d e929f028 7d4ac42c
>>>>> <7d49c12e> eb7b0000 7e99a378 4bffff3c
>>>> The faulting instruction address, 0xc000000022009c6, corresponds to the code
>>>> below:
>>>>
>>>> File:
>>>> arch/powerpc/kernel/setup-common.c
>>>>
>>>> Function
>>>> void __init smp_setup_cpu_maps(void)
>>>> {
>>>> ...
>>>> cpu_to_phys_id[bt_thread] =
>>>> be32_to_cpu(intserv_node->intserv[bt_thread]);
>>>> ...
>>>> }
>>>>
>>>> Hope it helps.
>>>>
>>> Appreciate your help.
>>>
>>> This issue should be linked with the capability of cpu_to_phys_id[].
>>>
>>> Could you please to try the fix suggested at the end of the email?
>>> It should be a fix for
>>> [PATCHv8 3/5] powerpc/setup: Handle the case when boot_cpuid greater than nr_cpus
>>>
>>>
>>> Thanks,
>>>
>>> Pingfan
>>>
>>> ---
>>>
>>> diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
>>> index bd7853a4bc91..849adc7a4b47 100644
>>> --- a/arch/powerpc/kernel/setup-common.c
>>> +++ b/arch/powerpc/kernel/setup-common.c
>>> @@ -464,12 +464,6 @@ void __init smp_setup_cpu_maps(void)
>>> DBG("smp_setup_cpu_maps()\n");
>>>
>>> INIT_LIST_HEAD(&head);
>>> - cpu_to_phys_id = memblock_alloc(nr_cpu_ids * sizeof(u32),
>>> - __alignof__(u32));
>>> - if (!cpu_to_phys_id)
>>> - panic("%s: Failed to allocate %zu bytes align=0x%zx\n",
>>> - __func__, nr_cpu_ids * sizeof(u32), __alignof__(u32));
>>> -
>>> for_each_node_by_type(dn, "cpu") {
>>> const __be32 *intserv;
>>> __be32 cpu_be;
>>> @@ -533,6 +527,16 @@ void __init smp_setup_cpu_maps(void)
>>> }
>>>
>>> }
>>> +
>>> + /* There may be hole between cpu0 and boot cpu */
>>> + j = (bt_thread + 1) > nr_cpu_ids ? (bt_thread + 1) : nr_cpu_ids;
>>> + cpu_to_phys_id = memblock_alloc(j * sizeof(u32),
>>> + __alignof__(u32));
>>> + if (!cpu_to_phys_id)
>>> + panic("%s: Failed to allocate %zu bytes align=0x%zx\n",
>>> + __func__, nr_cpu_ids * sizeof(u32), __alignof__(u32));
>>> +
>>> +
>>> cpu = 0;
>>> list_del_init(&head);
>>> /* Select the primary thread, the boot cpu's slibing, as the logic 0 */
>> With the above changes applied, kdump kernel boots fine with a WARNING:
>>
>> [root]# echo c > /proc/sysrq-trigger
>> [ 310.748248] sysrq: Trigger a crash
>> [ 310.748256] Kernel panic - not syncing: sysrq triggered crash
>> [ 310.748266] CPU: 26 PID: 2610 Comm: bash Kdump: loaded Not tainted
>> 6.6.0-rc5-fix-setup-common+ #3
>> [ 310.748273] Hardware name: IBM,9043-MRX POWER10 hv:phyp pSeries
>> [ 310.748280] Call Trace:
>> [ 310.748284] [c000000184717ac0] [c000000000ecf8d8]
>> dump_stack_lvl+0x6c/0x9c (unreliable)
>> [ 310.748298] [c000000184717af0] [c000000000150310] panic+0x178/0x438
>> [ 310.748307] [c000000184717b90] [c00000000092c8b8]
>> sysrq_handle_crash+0x28/0x30
>> [ 310.748316] [c000000184717bf0] [c00000000092d2ac]
>> __handle_sysrq+0x10c/0x250
>> [ 310.748330] [c000000184717c90] [c00000000092db18]
>> write_sysrq_trigger+0xc8/0x168
>> [ 310.748339] [c000000184717cd0] [c00000000065c21c]
>> proc_reg_write+0x10c/0x1b0
>> [ 310.748349] [c000000184717d00] [c000000000583f94] vfs_write+0x104/0x4b0
>> [ 310.748356] [c000000184717dc0] [c00000000058451c] ksys_write+0x7c/0x140
>> [ 310.748365] [c000000184717e10] [c000000000033a54]
>> system_call_exception+0x144/0x3a0
>> [ 310.748377] [c000000184717e50] [c00000000000c554]
>> system_call_common+0xf4/0x258
>> [ 310.748389] --- interrupt: c00 at 0x7fff97720c34
>> [ 310.748395] NIP: 00007fff97720c34 LR: 00007fff97697c74 CTR:
>> 0000000000000000
>> [ 310.748404] REGS: c000000184717e80 TRAP: 0c00 Not tainted
>> (6.6.0-rc5-fix-setup-common+)
>> [ 310.748413] MSR: 800000000280f033
>> <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 28222202 XER: 00000000
>> [ 310.748430] IRQMASK: 0
>> [ 310.748430] GPR00: 0000000000000004 00007fffffabc510 00007fff97807300
>> 0000000000000001
>> [ 310.748430] GPR04: 00000001624f7910 0000000000000002 0000000000000010
>> 00007fff97669724
>> [ 310.748430] GPR08: 0000000000000000 0000000000000000 0000000000000000
>> 0000000000000000
>> [ 310.748430] GPR12: 0000000000000000 00007fff97a5aee0 0000000040000000
>> 0000000125c39798
>> [ 310.748430] GPR16: 0000000125c39724 0000000125bd8128 0000000125b70370
>> 0000000125c3d568
>> [ 310.748430] GPR20: 0000000162551030 0000000000000001 0000000125beaf18
>> 00007fffffabc734
>> [ 310.748430] GPR24: 00007fffffabc730 0000000125c3af94 0000000000000002
>> 00000001624f7910
>> [ 310.748430] GPR28: 0000000000000002 00007fff97801798 00000001624f7910
>> 0000000000000002
>> [ 310.748475] NIP [00007fff97720c34] 0x7fff97720c34
>> [ 310.748478] LR [00007fff97697c74] 0x7fff97697c74
>> [ 310.748482] --- interrupt: c00
>> I'm in purgatory
>> [ 0.000000] radix-mmu: Page sizes from device-tree:
>> [ 0.000000] radix-mmu: Page size shift = 12 AP=0x0
>> [ 0.000000] radix-mmu: Page size shift = 16 AP=0x5
>> [ 0.000000] radix-mmu: Page size shift = 21 AP=0x1
>> [ 0.000000] radix-mmu: Page size shift = 30 AP=0x2
>> [ 0.000000] Activating Kernel Userspace Access Prevention
>> [ 0.000000] Activating Kernel Userspace Execution Prevention
>> [ 0.000000] radix-mmu: Mapped 0x0000000000000000-0x0000000000010000
>> with 64.0 KiB pages (exec)
>> [ 0.000000] radix-mmu: Mapped 0x0000000000010000-0x0000000000200000
>> with 64.0 KiB pages
>> [ 0.000000] radix-mmu: Mapped 0x0000000000200000-0x0000000020000000
>> with 2.00 MiB pages
>> [ 0.000000] radix-mmu: Mapped 0x0000000020000000-0x0000000022600000
>> with 2.00 MiB pages (exec)
>> [ 0.000000] radix-mmu: Mapped 0x0000000022600000-0x0000000040000000
>> with 2.00 MiB pages
>>
>> Trimmed logs ....
>>
>> [ 0.001738] Mount-cache hash table entries: 16384 (order: 1, 131072
>> bytes, linear)
>> [ 0.001751] Mountpoint-cache hash table entries: 16384 (order: 1,
>> 131072 bytes, linear)
>> [ 0.007339] ------------[ cut here ]------------
>> [ 0.007356] WARNING: CPU: 2 PID: 1 at arch/powerpc/kernel/smp.c:941
>> update_mask_from_threadgroup+0x128/0x1a0
>> [ 0.007371] Modules linked in:
>> [ 0.007377] CPU: 2 PID: 1 Comm: swapper/2 Not tainted
>> 6.6.0-rc5-fix-setup-common+ #3
>> [ 0.007385] Hardware name: IBM,9043-MRX POWER10 hv:phyp pSeries
>> [ 0.007393] NIP: c000000022011ed8 LR: c000000022011e10 CTR:
>> 0000000000000000
>> [ 0.007411] REGS: c0000000256338f0 TRAP: 0700 Not tainted
>> (6.6.0-rc5-fix-setup-common+)
>> [ 0.007425] MSR: 8000000002029033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR:
>> 44000842 XER: 0000000c
>> [ 0.007444] CFAR: c000000022011e78 IRQMASK: 0
>> [ 0.007444] GPR00: c000000022011e10 c000000025633b90 c0000000213c1300
>> 0000000000000002
>> [ 0.007444] GPR04: 0000000000000000 0000000000000005 0000000000000001
>> 0000000000000002
>> [ 0.007444] GPR08: 0000000000000008 0000000000000001 0000000000000002
>> 0000000000000004
>> [ 0.007444] GPR12: 0000000000000000 c000000022e3ac00 c000000020010138
>> 0000000000000000
>> [ 0.007444] GPR16: 0000000000000000 0000000000000000 0000000000000000
>> 0000000000000000
>> [ 0.007444] GPR20: 0000000000000018 c000000022150968 c000000022093580
>> c0000000253df000
>> [ 0.007444] GPR24: 0000000000000002 0000000000000000 c000000022b32058
>> 0000000000000000
>> [ 0.007444] GPR28: c00000015fca0a68 c000000022ba0330 c00000002209352c
>> 0000000000000000
>> [ 0.007520] NIP [c000000022011ed8]
>> update_mask_from_threadgroup+0x128/0x1a0
>> [ 0.007528] LR [c000000022011e10] update_mask_from_threadgroup+0x60/0x1a0
>> [ 0.007536] Call Trace:
>> [ 0.007539] [c000000025633b90] [c000000022011e10]
>> update_mask_from_threadgroup+0x60/0x1a0 (unreliable)
>> [ 0.007550] [c000000025633be0] [c000000022012210]
>> init_thread_group_cache_map+0x2c0/0x338
>> [ 0.007559] [c000000025633c50] [c0000000220125a0]
>> smp_prepare_cpus+0x318/0x510
>> [ 0.007568] [c000000025633d10] [c000000022004874]
>> kernel_init_freeable+0x198/0x3cc
>> [ 0.007578] [c000000025633de0] [c000000020010164] kernel_init+0x34/0x1b0
>> [ 0.007586] [c000000025633e50] [c00000002000cd94]
>> ret_from_kernel_user_thread+0x14/0x1c
>> [ 0.007596] --- interrupt: 0 at 0x0
>> [ 0.007601] NIP: 0000000000000000 LR: 0000000000000000 CTR:
>> 0000000000000000
>> [ 0.007608] REGS: c000000025633e80 TRAP: 0000 Not tainted
>> (6.6.0-rc5-fix-setup-common+)
>> [ 0.007632] MSR: 0000000000000000 <> CR: 00000000 XER: 00000000
>> [ 0.007651] CFAR: 0000000000000000 IRQMASK: 0
>> [ 0.007651] GPR00: 0000000000000000 0000000000000000 0000000000000000
>> 0000000000000000
>> [ 0.007651] GPR04: 0000000000000000 0000000000000000 0000000000000000
>> 0000000000000000
>> [ 0.007651] GPR08: 0000000000000000 0000000000000000 0000000000000000
>> 0000000000000000
>> [ 0.007651] GPR12: 0000000000000000 0000000000000000 0000000000000000
>> 0000000000000000
>> [ 0.007651] GPR16: 0000000000000000 0000000000000000 0000000000000000
>> 0000000000000000
>> [ 0.007651] GPR20: 0000000000000000 0000000000000000 0000000000000000
>> 0000000000000000
>> [ 0.007651] GPR24: 0000000000000000 0000000000000000 0000000000000000
>> 0000000000000000
>> [ 0.007651] GPR28: 0000000000000000 0000000000000000 0000000000000000
>> 0000000000000000
>> [ 0.007742] NIP [0000000000000000] 0x0
>> [ 0.007756] LR [0000000000000000] 0x0
>> [ 0.007769] --- interrupt: 0
>> [ 0.007779] Code: 7ca507b4 79081764 7d1e4214 8108000c 7f882000
>> 409effdc 48000010 38e70001 7ce707b4 4bffffa4 2f8affff 409e0010
>> <0fe00000> 3860ffc3 4800004c 7f9b5000
>> [ 0.007805] ---[ end trace 0000000000000000 ]---
>> [ 0.007997] RCU Tasks Rude: Setting shift to 2 and lim to 1
>> rcu_task_cb_adjust=1.
>> [ 0.008018] RCU Tasks Trace: Setting shift to 2 and lim to 1
>> rcu_task_cb_adjust=1.
>> [ 0.008043] POWER10 performance monitor hardware support registered
>> [ 0.008071] rcu: Hierarchical SRCU implementation.
>> [ 0.008078] rcu: Max phase no-delay instances is 1000.
>> [ 0.008516] smp: Bringing up secondary CPUs ...
>> [ 0.008735] smp: Brought up 1 node, 2 CPUs
>> ...
>>
>> Note: no warning observed if crashing CPU is 0, 8, 16, 24, 32, ....
>>
>> Code that generates warning:
>>
>> File: arch/powerpc/kernel/smp.c
>> Function: update_mask_from_threadgroup
>> ...
>> if (unlikely(i_group_start == -1)) {
>> WARN_ON_ONCE(1);
>> return -ENODATA;
>> }
>>
> It seems that the crash cpu passed the statements in
> init_thread_group_cache_map()
> {
> if (unlikely(cpu_group_start == -1)) {
> WARN_ON_ONCE(1);
> return -ENODATA;
> }
>
> }
>
> But raising warn in the above snippet. So it means that
> get_cpu_thread_group_start(i, tg) for the @first_thread failed in
> update_mask_from_threadgroup(). At present, I have no idea about it.
>
>
> And is this warning observed if only applying [1-2/5] ?
No warning observed with just 1-2/5 patches.
>
> According to my collected data, percpu area will cost 1792 kB per cpu.
> Forcing all eight threads in a core online will cost 107z52KB more than
> the result if applying the whole series. Maybe I can put [3-5/5] aside
> as Hari suggested, and try them later if needed.
In my experiment 7MB was allocated for Percpu for both nr_cpus=1 and
nr_cpus=8 if only 1-2/5 patches are applied.
Trimmed output of lscpu and cat /proc/meminfo
With nr_cpus=1
============
kdump:/# lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 8
On-line CPU(s) list: 0,3
Off-line CPU(s) list: 1,2,4-7
Model name: POWER10
kdump:/#
kdump:/# cat /proc/meminfo | grep Percpu
Percpu: 7168 kB
kdump:/#
with nr_cpus=8
============
kdump:/# lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 8
On-line CPU(s) list: 0,2
Off-line CPU(s) list: 1,3-7
Model name: POWER10
kdump:/#
kdump:/# cat /proc/meminfo | grep Percpu
Percpu: 7168 kB
Thanks,
Sourabh Jain
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