From e49cc0da7283088c5e03d475ffe2fdcb24a6d5b1 Mon Sep 17 00:00:00 2001 From: Yanmin Zhang Date: Wed, 23 May 2012 15:39:45 +0000 Subject: ipv4: fix the rcu race between free_fib_info and ip_route_output_slow We hit a kernel OOPS. <3>[23898.789643] BUG: sleeping function called from invalid context at /data/buildbot/workdir/ics/hardware/intel/linux-2.6/arch/x86/mm/fault.c:1103 <3>[23898.862215] in_atomic(): 0, irqs_disabled(): 0, pid: 10526, name: Thread-6683 <4>[23898.967805] HSU serial 0000:00:05.1: 0000:00:05.2:HSU serial prevented me to suspend... <4>[23899.258526] Pid: 10526, comm: Thread-6683 Tainted: G W 3.0.8-137685-ge7742f9 #1 <4>[23899.357404] HSU serial 0000:00:05.1: 0000:00:05.2:HSU serial prevented me to suspend... <4>[23899.904225] Call Trace: <4>[23899.989209] [] ? pgtable_bad+0x130/0x130 <4>[23900.000416] [] __might_sleep+0x10a/0x110 <4>[23900.007357] [] do_page_fault+0xd1/0x3c0 <4>[23900.013764] [] ? restore_all+0xf/0xf <4>[23900.024024] [] ? napi_complete+0x8b/0x690 <4>[23900.029297] [] ? pgtable_bad+0x130/0x130 <4>[23900.123739] [] ? pgtable_bad+0x130/0x130 <4>[23900.128955] [] error_code+0x5f/0x64 <4>[23900.133466] [] ? pgtable_bad+0x130/0x130 <4>[23900.138450] [] ? __ip_route_output_key+0x698/0x7c0 <4>[23900.144312] [] ? __ip_route_output_key+0x38d/0x7c0 <4>[23900.150730] [] ip_route_output_flow+0x1f/0x60 <4>[23900.156261] [] ip4_datagram_connect+0x188/0x2b0 <4>[23900.161960] [] ? _raw_spin_unlock_bh+0x1f/0x30 <4>[23900.167834] [] inet_dgram_connect+0x36/0x80 <4>[23900.173224] [] ? _copy_from_user+0x48/0x140 <4>[23900.178817] [] sys_connect+0x9a/0xd0 <4>[23900.183538] [] ? alloc_file+0xdc/0x240 <4>[23900.189111] [] ? sub_preempt_count+0x3d/0x50 Function free_fib_info resets nexthop_nh->nh_dev to NULL before releasing fi. Other cpu might be accessing fi. Fixing it by delaying the releasing. With the patch, we ran MTBF testing on Android mobile for 12 hours and didn't trigger the issue. Thank Eric for very detailed review/checking the issue. Signed-off-by: Yanmin Zhang Signed-off-by: Kun Jiang Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/fib_semantics.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'net') diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c index a8bdf7405433..e5b7182fa099 100644 --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -145,6 +145,12 @@ static void free_fib_info_rcu(struct rcu_head *head) { struct fib_info *fi = container_of(head, struct fib_info, rcu); + change_nexthops(fi) { + if (nexthop_nh->nh_dev) + dev_put(nexthop_nh->nh_dev); + } endfor_nexthops(fi); + + release_net(fi->fib_net); if (fi->fib_metrics != (u32 *) dst_default_metrics) kfree(fi->fib_metrics); kfree(fi); @@ -156,13 +162,7 @@ void free_fib_info(struct fib_info *fi) pr_warn("Freeing alive fib_info %p\n", fi); return; } - change_nexthops(fi) { - if (nexthop_nh->nh_dev) - dev_put(nexthop_nh->nh_dev); - nexthop_nh->nh_dev = NULL; - } endfor_nexthops(fi); fib_info_cnt--; - release_net(fi->fib_net); call_rcu(&fi->rcu, free_fib_info_rcu); } -- cgit v1.2.3-59-g8ed1b