From: Pekka Enberg Date: Mon, 23 Nov 2009 20:01:15 +0000 (+0200) Subject: SLAB: Fix lockdep annotations for CPU hotplug X-Git-Tag: v2.6.33-rc1~297^2^2~1 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ce79ddc8e2376a9a93c7d42daf89bfcbb9187e62;p=pandora-kernel.git SLAB: Fix lockdep annotations for CPU hotplug As reported by Paul McKenney: I am seeing some lockdep complaints in rcutorture runs that include frequent CPU-hotplug operations. The tests are otherwise successful. My first thought was to send a patch that gave each array_cache structure's ->lock field its own struct lock_class_key, but you already have a init_lock_keys() that seems to be intended to deal with this. ------------------------------------------------------------------------ ============================================= [ INFO: possible recursive locking detected ] 2.6.32-rc4-autokern1 #1 --------------------------------------------- syslogd/2908 is trying to acquire lock: (&nc->lock){..-...}, at: [] .kmem_cache_free+0x118/0x2d4 but task is already holding lock: (&nc->lock){..-...}, at: [] .kfree+0x1f0/0x324 other info that might help us debug this: 3 locks held by syslogd/2908: #0: (&u->readlock){+.+.+.}, at: [] .unix_dgram_recvmsg+0x70/0x338 #1: (&nc->lock){..-...}, at: [] .kfree+0x1f0/0x324 #2: (&parent->list_lock){-.-...}, at: [] .__drain_alien_cache+0x50/0xb8 stack backtrace: Call Trace: [c0000000e8ccafc0] [c0000000000101e4] .show_stack+0x70/0x184 (unreliable) [c0000000e8ccb070] [c0000000000afebc] .validate_chain+0x6ec/0xf58 [c0000000e8ccb180] [c0000000000b0ff0] .__lock_acquire+0x8c8/0x974 [c0000000e8ccb280] [c0000000000b2290] .lock_acquire+0x140/0x18c [c0000000e8ccb350] [c000000000468df0] ._spin_lock+0x48/0x70 [c0000000e8ccb3e0] [c0000000001407f4] .kmem_cache_free+0x118/0x2d4 [c0000000e8ccb4a0] [c000000000140b90] .free_block+0x130/0x1a8 [c0000000e8ccb540] [c000000000140f94] .__drain_alien_cache+0x80/0xb8 [c0000000e8ccb5e0] [c0000000001411e0] .kfree+0x214/0x324 [c0000000e8ccb6a0] [c0000000003ca860] .skb_release_data+0xe8/0x104 [c0000000e8ccb730] [c0000000003ca2ec] .__kfree_skb+0x20/0xd4 [c0000000e8ccb7b0] [c0000000003cf2c8] .skb_free_datagram+0x1c/0x5c [c0000000e8ccb830] [c00000000045597c] .unix_dgram_recvmsg+0x2f4/0x338 [c0000000e8ccb920] [c0000000003c0f14] .sock_recvmsg+0xf4/0x13c [c0000000e8ccbb30] [c0000000003c28ec] .SyS_recvfrom+0xb4/0x130 [c0000000e8ccbcb0] [c0000000003bfb78] .sys_recv+0x18/0x2c [c0000000e8ccbd20] [c0000000003ed388] .compat_sys_recv+0x14/0x28 [c0000000e8ccbd90] [c0000000003ee1bc] .compat_sys_socketcall+0x178/0x220 [c0000000e8ccbe30] [c0000000000085d4] syscall_exit+0x0/0x40 This patch fixes the issue by setting up lockdep annotations during CPU hotplug. Reported-by: Paul E. McKenney Tested-by: Paul E. McKenney Cc: Peter Zijlstra Cc: Christoph Lameter Signed-off-by: Pekka Enberg --- Reading git-diff-tree failed