Messages in this thread Patch in this message | | | From | Prarit Bhargava <> | Subject | Re: b1cbacc866 ("x86/smpboot: Do not use smp_num_siblings in .."): divide error: 0000 [#1] SMP DEBUG_PAGEALLOC | Date | Tue, 5 Dec 2017 09:30:36 -0500 |
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>[ 0.029102] Hierarchical SRCU implementation. >[ 0.030040] smp: Bringing up secondary CPUs ... >[ 0.030528] smp: Brought up 1 node, 1 CPU >[ 0.030953] divide error: 0000 [#1] SMP DEBUG_PAGEALLOC >[ 0.031000] Modules linked in: >[ 0.031000] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.14.0-01223-gb1cbacc #1 >[ 0.031000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 >[ 0.031000] task: ffff88001e460000 task.stack: ffffc90000008000
A single socket/package, single core, single thread system has 1 thread. __max_smt_threads is not set to 1 since smp_callin() is never called. The minimum value of __max_smt_threads must be 1.
tglx, this is built on -tip.
P. ----8<----
Subject: [PATCH] arch/x86: Initialize __max_smt_threads to 1
A single socket, single core, single thread system has __max_smt_threads set to 0 since smp_callin() is not called.
__max_smt_threads must be a minimum of 1.
Fixes: b1cbacc8663a ("x86/smpboot: Do not use smp_num_siblings in __max_logical_packages calculation) Signed-off-by: Prarit Bhargava <prarit@redhat.com> Cc: Jakub Kicinski <kubakici@wp.pl> Cc: netdev@vger.kernel.org Cc: "netdev@vger.kernel.org" Cc: Clark Williams <williams@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: x86@kernel.org Link: https://marc.info/?t=151246092100004&r=1&w=2 --- arch/x86/kernel/smpboot.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index eaee15fb7d8b..882c61e1d7a2 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -106,7 +106,7 @@ EXPORT_SYMBOL(__max_logical_packages); static unsigned int logical_packages __read_mostly; /* Maximum number of SMT threads on any online core */ -int __max_smt_threads __read_mostly; +int __read_mostly __max_smt_threads = 1; /* Flag to indicate if a complete sched domain rebuild is required */ bool x86_topology_update; -- 2.15.0.rc0.39.g2f0e14e64
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