From: "Aneesh Kumar K.V" aneesh.kumar@linux.ibm.com
[ Upstream commit 16f6b67cf03cb43db7104acb2ca877bdc2606c92 ]
With large memory (8TB and more) hotplug, we can get soft lockup warnings as below. These were caused by a long loop without any explicit cond_resched which is a problem for !PREEMPT kernels.
Avoid this using cond_resched() while inserting hash page table entries. We already do similar cond_resched() in __add_pages(), see commit f64ac5e6e306 ("mm, memory_hotplug: add scheduling point to __add_pages").
rcu: 3-....: (24002 ticks this GP) idle=13e/1/0x4000000000000002 softirq=722/722 fqs=12001 (t=24003 jiffies g=4285 q=2002) NMI backtrace for cpu 3 CPU: 3 PID: 3870 Comm: ndctl Not tainted 5.3.0-197.18-default+ #2 Call Trace: dump_stack+0xb0/0xf4 (unreliable) nmi_cpu_backtrace+0x124/0x130 nmi_trigger_cpumask_backtrace+0x1ac/0x1f0 arch_trigger_cpumask_backtrace+0x28/0x3c rcu_dump_cpu_stacks+0xf8/0x154 rcu_sched_clock_irq+0x878/0xb40 update_process_times+0x48/0x90 tick_sched_handle.isra.16+0x4c/0x80 tick_sched_timer+0x68/0xe0 __hrtimer_run_queues+0x180/0x430 hrtimer_interrupt+0x110/0x300 timer_interrupt+0x108/0x2f0 decrementer_common+0x114/0x120 --- interrupt: 901 at arch_add_memory+0xc0/0x130 LR = arch_add_memory+0x74/0x130 memremap_pages+0x494/0x650 devm_memremap_pages+0x3c/0xa0 pmem_attach_disk+0x188/0x750 nvdimm_bus_probe+0xac/0x2c0 really_probe+0x148/0x570 driver_probe_device+0x19c/0x1d0 device_driver_attach+0xcc/0x100 bind_store+0x134/0x1c0 drv_attr_store+0x44/0x60 sysfs_kf_write+0x64/0x90 kernfs_fop_write+0x1a0/0x270 __vfs_write+0x3c/0x70 vfs_write+0xd0/0x260 ksys_write+0xdc/0x130 system_call+0x5c/0x68
Signed-off-by: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20191001084656.31277-1-aneesh.kumar@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/mm/hash_utils_64.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c index cf1d76e036359..387600ecea60a 100644 --- a/arch/powerpc/mm/hash_utils_64.c +++ b/arch/powerpc/mm/hash_utils_64.c @@ -303,6 +303,7 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend, if (ret < 0) break;
+ cond_resched(); #ifdef CONFIG_DEBUG_PAGEALLOC if (debug_pagealloc_enabled() && (paddr >> PAGE_SHIFT) < linear_map_hash_count)