On 28.04.22 20:35, Elliot Berman wrote:
From: Prakruthi Deepak Heragu <quic_pheragu@xxxxxxxxxxx>
During hotplug, the stolen time data structure is unmapped and memset.
There is a possibility of the timer IRQ being triggered before memset
and stolen time is getting updated as part of this timer IRQ handler. This
causes the below crash in timer handler -
[ 3457.473139][ C5] Unable to handle kernel paging request at virtual address ffffffc03df05148
...
[ 3458.154398][ C5] Call trace:
[ 3458.157648][ C5] para_steal_clock+0x30/0x50
[ 3458.162319][ C5] irqtime_account_process_tick+0x30/0x194
[ 3458.168148][ C5] account_process_tick+0x3c/0x280
[ 3458.173274][ C5] update_process_times+0x5c/0xf4
[ 3458.178311][ C5] tick_sched_timer+0x180/0x384
[ 3458.183164][ C5] __run_hrtimer+0x160/0x57c
[ 3458.187744][ C5] hrtimer_interrupt+0x258/0x684
[ 3458.192698][ C5] arch_timer_handler_virt+0x5c/0xa0
[ 3458.198002][ C5] handle_percpu_devid_irq+0xdc/0x414
[ 3458.203385][ C5] handle_domain_irq+0xa8/0x168
[ 3458.208241][ C5] gic_handle_irq.34493+0x54/0x244
[ 3458.213359][ C5] call_on_irq_stack+0x40/0x70
[ 3458.218125][ C5] do_interrupt_handler+0x60/0x9c
[ 3458.223156][ C5] el1_interrupt+0x34/0x64
[ 3458.227560][ C5] el1h_64_irq_handler+0x1c/0x2c
[ 3458.232503][ C5] el1h_64_irq+0x7c/0x80
[ 3458.236736][ C5] free_vmap_area_noflush+0x108/0x39c
[ 3458.242126][ C5] remove_vm_area+0xbc/0x118
[ 3458.246714][ C5] vm_remove_mappings+0x48/0x2a4
[ 3458.251656][ C5] __vunmap+0x154/0x278
[ 3458.255796][ C5] stolen_time_cpu_down_prepare+0xc0/0xd8
[ 3458.261542][ C5] cpuhp_invoke_callback+0x248/0xc34
[ 3458.266842][ C5] cpuhp_thread_fun+0x1c4/0x248
[ 3458.271696][ C5] smpboot_thread_fn+0x1b0/0x400
[ 3458.276638][ C5] kthread+0x17c/0x1e0
[ 3458.280691][ C5] ret_from_fork+0x10/0x20
As a fix, introduce rcu lock to update stolen time structure.
Fixes: 75df529bec91 ("arm64: paravirt: Initialize steal time when cpu is online")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Prakruthi Deepak Heragu <quic_pheragu@xxxxxxxxxxx>
Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx> Juergen
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