The following deadlock is observed.
Core 2 waiting on mapping->tree_lock which is taken by core 6
do_raw_spin_lock
raw_spin_lock_irq
atomic_cmpxchg
page_freeze_refs
__remove_mapping
shrink_page_list
shrink_inactive_list
shrink_list
shrink_lruvec
shrink_zone
shrink_zones
do_try_to_free_pages
try_to_free_pages(?, ?, ?, ?)
__perform_reclaim
__alloc_pages_direct_reclaim
__alloc_pages_slowpath
__alloc_pages_nodemask
alloc_kmem_pages_node
alloc_thread_info_node
dup_task_struct
copy_process.part.56
do_fork
sys_clone
el0_svc_naked
Core 6 after taking mapping->tree_lock is waiting on zbud pool lock
which is held by core 5
zbud_alloc
zcache_store_page
__cleancache_put_page
cleancache_put_page
__delete_from_page_cache
spin_unlock_irq
__remove_mapping
shrink_page_list
shrink_inactive_list
shrink_list
shrink_lruvec
shrink_zone
bitmap_zero
__nodes_clear
kswapd_shrink_zone.constprop.58
balance_pgdat
kswapd_try_to_sleep
kswapd
kthread
ret_from_fork
Core 5 after taking zbud pool lock from zbud_free received an IRQ, and
after IRQ exit, softirqs were scheduled and end_page_writeback tried to
lock on mapping->tree_lock which is already held by Core 6. Deadlock.
do_raw_spin_lock
raw_spin_lock_irqsave
test_clear_page_writeba
end_page_writeback
ext4_finish_bio
ext4_end_bio
bio_endio
blk_update_request
end_clone_bio
bio_endio
blk_update_request
blk_update_bidi_request
blk_end_bidi_request
blk_end_request
mmc_blk_cmdq_complete_r
mmc_cmdq_softirq_done
blk_done_softirq
static_key_count
static_key_false
trace_softirq_exit
__do_softirq()
tick_irq_exit
irq_exit()
set_irq_regs
__handle_domain_irq
gic_handle_irq
el1_irq
exception
__list_del_entry
list_del
zbud_free
zcache_load_page
__cleancache_get_page(?
So protect zbud_alloc/free/reclaim with spink_lock_bh
CRs-Fixed: 986783
Change-Id: Ib0605b38e7371c29316ed81e43549a0b9503d531
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
30781083ea