On Mon 12-06-17 06:17:20, Sahitya Tummala wrote: > __list_lru_walk_one() can hold the spin lock for longer duration > if there are more number of entries to be isolated. > > This results in "BUG: spinlock lockup suspected" in the below path - > > [<ffffff8eca0fb0bc>] spin_bug+0x90 > [<ffffff8eca0fb220>] do_raw_spin_lock+0xfc > [<ffffff8ecafb7798>] _raw_spin_lock+0x28 > [<ffffff8eca1ae884>] list_lru_add+0x28 > [<ffffff8eca1f5dac>] dput+0x1c8 > [<ffffff8eca1eb46c>] path_put+0x20 > [<ffffff8eca1eb73c>] terminate_walk+0x3c > [<ffffff8eca1eee58>] path_lookupat+0x100 > [<ffffff8eca1f00fc>] filename_lookup+0x6c > [<ffffff8eca1f0264>] user_path_at_empty+0x54 > [<ffffff8eca1e066c>] SyS_faccessat+0xd0 > [<ffffff8eca084e30>] el0_svc_naked+0x24 > > This nlru->lock has been acquired by another CPU in this path - > > [<ffffff8eca1f5fd0>] d_lru_shrink_move+0x34 > [<ffffff8eca1f6180>] dentry_lru_isolate_shrink+0x48 > [<ffffff8eca1aeafc>] __list_lru_walk_one.isra.10+0x94 > [<ffffff8eca1aec34>] list_lru_walk_node+0x40 > [<ffffff8eca1f6620>] shrink_dcache_sb+0x60 > [<ffffff8eca1e56a8>] do_remount_sb+0xbc > [<ffffff8eca1e583c>] do_emergency_remount+0xb0 > [<ffffff8eca0ba510>] process_one_work+0x228 > [<ffffff8eca0bb158>] worker_thread+0x2e0 > [<ffffff8eca0c040c>] kthread+0xf4 > [<ffffff8eca084dd0>] ret_from_fork+0x10 > > Link: http://marc.info/?t=149511514800002&r=1&w=2 > Fix-suggested-by: Jan kara <jack@xxxxxxx> > Signed-off-by: Sahitya Tummala <stummala@xxxxxxxxxxxxxx> Looks good to me. You can add: Reviewed-by: Jan Kara <jack@xxxxxxx> Honza > --- > mm/list_lru.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/list_lru.c b/mm/list_lru.c > index 5d8dffd..1af0709 100644 > --- a/mm/list_lru.c > +++ b/mm/list_lru.c > @@ -249,6 +249,8 @@ restart: > default: > BUG(); > } > + if (cond_resched_lock(&nlru->lock)) > + goto restart; > } > > spin_unlock(&nlru->lock); > -- > Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project. > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
