__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> --- 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.
