Commits
David Lebrun committed 191f86ca8ef
ipv6: sr: fix scheduling in RCU when creating seg6 lwtunnel state
The seg6_build_state() function is called with RCU read lock held,
so we cannot use GFP_KERNEL. This patch uses GFP_ATOMIC instead.
[ 92.770271] =============================
[ 92.770628] WARNING: suspicious RCU usage
[ 92.770921] 4.16.0-rc4+ #12 Not tainted
[ 92.771277] -----------------------------
[ 92.771585] ./include/linux/rcupdate.h:302 Illegal context switch in RCU read-side critical section!
[ 92.772279]
[ 92.772279] other info that might help us debug this:
[ 92.772279]
[ 92.773067]
[ 92.773067] rcu_scheduler_active = 2, debug_locks = 1
[ 92.773514] 2 locks held by ip/2413:
[ 92.773765] #0: (rtnl_mutex){+.+.}, at: [<00000000e5461720>] rtnetlink_rcv_msg+0x441/0x4d0
[ 92.774377] #1: (rcu_read_lock){....}, at: [<00000000df4f161e>] lwtunnel_build_state+0x59/0x210
[ 92.775065]
[ 92.775065] stack backtrace:
[ 92.775371] CPU: 0 PID: 2413 Comm: ip Not tainted 4.16.0-rc4+ #12
[ 92.775791] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1.fc27 04/01/2014
[ 92.776608] Call Trace:
[ 92.776852] dump_stack+0x7d/0xbc
[ 92.777130] __schedule+0x133/0xf00
[ 92.777393] ? unwind_get_return_address_ptr+0x50/0x50
[ 92.777783] ? __sched_text_start+0x8/0x8
[ 92.778073] ? rcu_is_watching+0x19/0x30
[ 92.778383] ? kernel_text_address+0x49/0x60
[ 92.778800] ? __kernel_text_address+0x9/0x30
[ 92.779241] ? unwind_get_return_address+0x29/0x40
[ 92.779727] ? pcpu_alloc+0x102/0x8f0
[ 92.780101] _cond_resched+0x23/0x50
[ 92.780459] __mutex_lock+0xbd/0xad0
[ 92.780818] ? pcpu_alloc+0x102/0x8f0
[ 92.781194] ? seg6_build_state+0x11d/0x240
[ 92.781611] ? save_stack+0x9b/0xb0
[ 92.781965] ? __ww_mutex_wakeup_for_backoff+0xf0/0xf0
[ 92.782480] ? seg6_build_state+0x11d/0x240
[ 92.782925] ? lwtunnel_build_state+0x1bd/0x210
[ 92.783393] ? ip6_route_info_create+0x687/0x1640
[ 92.783846] ? ip6_route_add+0x74/0x110
[ 92.784236] ? inet6_rtm_newroute+0x8a/0xd0
Fixes: 6c8702c60b886 ("ipv6: sr: add support for SRH encapsulation and injection with lwtunnels")
Signed-off-by: David Lebrun <dlebrun@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>