On Mon, Oct 16, 2023 at 12:13:53PM +0530, Sourabh Jain wrote:
> 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@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx) (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.
>
Good to know it. I think that [1-2/5] can be a first step.
I will post V9, which trims [3-5/5] later.
> >
> > 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
The nr_cpus has the semantic of possible cpu, instead of online cpu.
It includes both On-line and Off-line CPU(s) list.
So Percpu area allocates memory for eight cpus.
> 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
>
Here Percpu area also allocates memory for eight cpus, hence the size is
identical to the former one.
Again, thank you for your help and precious time.
Regards,
Pingfan
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