• Patrick McHardy's avatar
    [NET]: Handle disabled preemption in gfp_any() · 4498121c
    Patrick McHardy authored
    
    
    ctnetlink uses netlink_unicast from an atomic_notifier_chain
    (which is called within a RCU read side critical section)
    without holding further locks. netlink_unicast calls netlink_trim
    with the result of gfp_any() for the gfp flags, which are passed
    down to pskb_expand_header. gfp_any() only checks for softirq
    context and returns GFP_KERNEL, resulting in this warning:
    
    BUG: sleeping function called from invalid context at mm/slab.c:3032
    in_atomic():1, irqs_disabled():0
    no locks held by rmmod/7010.
    
    Call Trace:
     [<ffffffff8109467f>] debug_show_held_locks+0x9/0xb
     [<ffffffff8100b0b4>] __might_sleep+0xd9/0xdb
     [<ffffffff810b5082>] __kmalloc+0x68/0x110
     [<ffffffff811ba8f2>] pskb_expand_head+0x4d/0x13b
     [<ffffffff81053147>] netlink_broadcast+0xa5/0x2e0
     [<ffffffff881cd1d7>] :nfnetlink:nfnetlink_send+0x83/0x8a
     [<ffffffff8834f6a6>] :nf_conntrack_netlink:ctnetlink_conntrack_event+0x94c/0x96a
     [<ffffffff810624d6>] notifier_call_chain+0x29/0x3e
     [<ffffffff8106251d>] atomic_notifier_call_chain+0x32/0x60
     [<ffffffff881d266d>] :nf_conntrack:destroy_conntrack+0xa5/0x1d3
     [<ffffffff881d194e>] :nf_conntrack:nf_ct_cleanup+0x8c/0x12c
     [<ffffffff881d4614>] :nf_conntrack:kill_l3proto+0x0/0x13
     [<ffffffff881d482a>] :nf_conntrack:nf_conntrack_l3proto_unregister+0x90/0x94
     [<ffffffff883551b3>] :nf_conntrack_ipv4:nf_conntrack_l3proto_ipv4_fini+0x2b/0x5d
     [<ffffffff8109d44f>] sys_delete_module+0x1b5/0x1e6
     [<ffffffff8105f245>] trace_hardirqs_on_thunk+0x35/0x37
     [<ffffffff8105911e>] system_call+0x7e/0x83
    
    Since netlink_unicast is supposed to be callable from within RCU
    read side critical sections, make gfp_any() check for in_atomic()
    instead of in_softirq().
    
    Additionally nfnetlink_send needs to use gfp_any() as well for the
    call to netlink_broadcast).
    Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    4498121c
sock.h 40.3 KB