Re: [PATCH] powerpc/cpu: nr_cpu_ids should be aligned on threads_per_core
Hi Pingfan,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on powerpc/next]
[also build test ERROR on v4.17-rc5 next-20180511]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system]
url:
https://github.com/0day-ci/linux/commits/Pingfan-Liu/powerpc-cpu-nr_cpu_ids-should-be-aligned-on-threads_per_core/20180514-141629
base: https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-allnoconfig (attached as .config)
compiler: powerpc-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
wget
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
make.cross ARCH=powerpc
All errors (new ones prefixed by >>):
arch/powerpc/kernel/prom.c: In function 'early_init_dt_scan_cpus':
>> arch/powerpc/kernel/prom.c:370:14: error: lvalue required as left operand of
>> assignment
nr_cpu_ids = nr_cpus_aligned;
^
vim +370 arch/powerpc/kernel/prom.c
306
307 static int __init early_init_dt_scan_cpus(unsigned long node,
308const char *uname, int depth,
309void *data)
310 {
311 const char *type = of_get_flat_dt_prop(node, "device_type",
NULL);
312 const __be32 *prop;
313 const __be32 *intserv;
314 int i, nthreads;
315 int len;
316 int found = -1;
317 int found_thread = 0;
318 unsigned int nr_cpus_aligned;
319
320 /* We are scanning "cpu" nodes only */
321 if (type == NULL || strcmp(type, "cpu") != 0)
322 return 0;
323
324 /* Get physical cpuid */
325 intserv = of_get_flat_dt_prop(node,
"ibm,ppc-interrupt-server#s", &len);
326 if (!intserv)
327 intserv = of_get_flat_dt_prop(node, "reg", &len);
328
329 nthreads = len / sizeof(int);
330
331 /*
332 * Now see if any of these threads match our boot cpu.
333 * NOTE: This must match the parsing done in smp_setup_cpu_maps.
334 */
335 for (i = 0; i < nthreads; i++) {
336 /*
337 * version 2 of the kexec param format adds the phys
cpuid of
338 * booted proc.
339 */
340 if (fdt_version(initial_boot_params) >= 2) {
341 if (be32_to_cpu(intserv[i]) ==
342 fdt_boot_cpuid_phys(initial_boot_params)) {
343 found = boot_cpu_count;
344 found_thread = i;
345 }
346 } else {
347 /*
348 * Check if it's the boot-cpu, set it's hw
index now,
349 * unfortunately this format did not support
booting
350 * off secondary threads.
351 */
352 if (of_get_flat_dt_prop(node,
353 "linux,boot-cpu", NULL) != NULL)
354 found = boot_cpu_count;
355 }
356 #ifdef CONFIG_SMP
357 /* logical cpu id is always 0 on UP kernels */
358 boot_cpu_count++;
359 #endif
360 }
361
362 /* Not the boot CPU */
363 if (found < 0)
364 return 0;
365 /* to work around p8 subcore mode */
366 nr_cpus_aligned = _ALIGN_UP(nr_cpu_ids, nthreads);
367 if (nr_cpus_aligned != nr_cpu_ids) {
368 pr_info("nr_cpus is forced to align up on
threads_per_core,"
369 "from %u to %u\n", nr_cpu_ids, nr_cpus_aligned);
> 370 nr_cpu_ids = nr_cpus_aligned;
371 }
372 DBG("boot cpu: logical %d physical %d\n", found,
373 be32_to_cpu(intserv[found_thread]));
374 boot_cpuid = found;
375
376 /*
377 * PAPR defines "logical" PVR values for cpus that
378 * meet various levels of the architecture:
379 * 0x0f01 Architecture version 2.04
380 * 0x0f02 Architecture version 2.05
381 * If the cpu-version property in the cpu node contains
382 * such a value, we call identify_cpu again with the
383 * logical PVR value in order to use the cpu feature
384 * bits appropriate for the architecture level.
385 *
386 * A POWER6 partition in "POWER6 architected" mode
[PATCH] powerpc/cpu: nr_cpu_ids should be aligned on threads_per_core
With p8 subcore mode, if nr_cpus is not aligned on threads_per_core,
then we will hit the following panic:
[0.310006] Unpacking initramfs...
[1.105015] Freeing initrd memory: 35968K
[1.105466] rtas_flash: no firmware flash support
[1.105688] Unable to handle kernel paging request for data at address
0x1035
[1.105768] Faulting instruction address: 0xc0099bb8
[1.105837] Oops: Kernel access of bad area, sig: 11 [#1]
[1.105890] LE SMP NR_CPUS=2048 NUMA PowerNV
[1.105947] Modules linked in:
[1.105992] CPU: 8 PID: 11 Comm: migration/8 Not tainted 4.17.0-rc4+ #26
[1.106059] NIP: c0099bb8 LR: c00ac554 CTR:
c0099b70
[1.106139] REGS: c00ff649f860 TRAP: 0380 Not tainted (4.17.0-rc4+)
[1.106205] MSR: 90001033 CR: 28004022
XER:
[1.106293] CFAR: c00ac550 SOFTE: 3
[1.106293] GPR00: c00ac554 c00ff649fae0 c12e6d00
0060
[1.106293] GPR04: 0001 c00ac914 90001033
c03fff80
[1.106293] GPR08: 0001
90001003
[1.106293] GPR12: c0099b70 c170 c0141c28
c00ffa201180
[1.106293] GPR16:
[1.106293] GPR20: 0001
c00fffd13840
[1.106293] GPR24: c00fffd13838 0001
0010
[1.106293] GPR28: 0008 0001 c1370548
000c
[1.106984] NIP [c0099bb8] icp_native_cause_ipi+0x48/0x70
[1.107053] LR [c00ac554] pnv_cause_ipi+0x54/0x80
[1.107106] Call Trace:
[1.107137] [c00ff649fae0] [c00478b4]
doorbell_try_core_ipi+0x74/0x90 (unreliable)
[1.107232] [c00ff649fb10] [c00ac554] pnv_cause_ipi+0x54/0x80
[1.107301] [c00ff649fb40] [c004ccfc]
smp_muxed_ipi_message_pass+0x6c/0x90
[1.107384] [c00ff649fb80] [c00acbe8] cpu_do_split+0x2b8/0x2f0
[1.107453] [c00ff649fbf0] [c00acdb8]
cpu_update_split_mode+0x68/0x204
[1.107536] [c00ff649fc40] [c0204ab8]
multi_cpu_stop+0x1c8/0x200
[1.107617] [c00ff649fca0] [c0204eb4]
cpu_stopper_thread+0x114/0x1f0
[1.107699] [c00ff649fd60] [c0148650]
smpboot_thread_fn+0x290/0x2a0
[1.107780] [c00ff649fdc0] [c0141d84] kthread+0x164/0x1b0
[1.107850] [c00ff649fe30] [c000b628]
ret_from_kernel_thread+0x5c/0xb4
[1.107929] Instruction dump:
[1.107971] 7c7f1b78 6000 6000 3d420004 394ab070 7be31f24 3921
e90a
[1.108058] 3d42001b 394a2650 7d08182a 7d4a182a <99281035> 3904
7c0004ac 990a000c
[1.108150] ---[ end trace 83dad19c162dc306 ]---
[1.110137]
[2.110227] Kernel panic - not syncing: Fatal exception
This is caused by that during subcore_init, it IPIs all cpu inside the core,
but due to the limitation
imposed by nr_cpus, there are no mem allocated for percpu cpu_sibling_map.
To avoid a complicated fix, this patch just forces the nr_cpu_ids to be aligned
on thread_per_code
at the cost of a bit more memory.
Signed-off-by: Pingfan Liu
---
arch/powerpc/kernel/prom.c | 9 -
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 9dbed48..358adb4 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -315,6 +315,7 @@ static int __init early_init_dt_scan_cpus(unsigned long
node,
int len;
int found = -1;
int found_thread = 0;
+ unsigned int nr_cpus_aligned;
/* We are scanning "cpu" nodes only */
if (type == NULL || strcmp(type, "cpu") != 0)
@@ -361,7 +362,13 @@ static int __init early_init_dt_scan_cpus(unsigned long
node,
/* Not the boot CPU */
if (found < 0)
return 0;
-
+ /* to work around p8 subcore mode */
+ nr_cpus_aligned = _ALIGN_UP(nr_cpu_ids, nthreads);
+ if (nr_cpus_aligned != nr_cpu_ids) {
+ pr_info("nr_cpus is forced to align up on threads_per_core,"
+ "from %u to %u\n", nr_cpu_ids, nr_cpus_aligned);
+ nr_cpu_ids = nr_cpus_aligned;
+ }
DBG("boot cpu: logical %d physical %d\n", found,
be32_to_cpu(intserv[found_thread]));
boot_cpuid = found;
--
2.7.4
