138470a9b2
Convert zones_lock spinlock to zones_mutex mutex, and struct (tcf_ct_flow_table)->ref to a refcount, so that control path can use regular GFP_KERNEL allocations from standard process context. This is more robust in case of memory pressure. The refcount is needed because tcf_ct_flow_table_put() can be called from RCU callback, thus in BH context. The issue was spotted by syzbot, as rhashtable_init() was called with a spinlock held, which is bad since GFP_KERNEL allocations can sleep. Note to developers : Please make sure your patches are tested with CONFIG_DEBUG_ATOMIC_SLEEP=y BUG: sleeping function called from invalid context at mm/slab.h:565 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 9582, name: syz-executor610 2 locks held by syz-executor610/9582: #0: ffffffff8a34eb80 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:72 [inline] #0: ffffffff8a34eb80 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x3f9/0xad0 net/core/rtnetlink.c:5437 #1: ffffffff8a3961b8 (zones_lock){+...}, at: spin_lock_bh include/linux/spinlock.h:343 [inline] #1: ffffffff8a3961b8 (zones_lock){+...}, at: tcf_ct_flow_table_get+0xa3/0x1700 net/sched/act_ct.c:67 Preemption disabled at: [<0000000000000000>] 0x0 CPU: 0 PID: 9582 Comm: syz-executor610 Not tainted 5.6.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 ___might_sleep.cold+0x1f4/0x23d kernel/sched/core.c:6798 slab_pre_alloc_hook mm/slab.h:565 [inline] slab_alloc_node mm/slab.c:3227 [inline] kmem_cache_alloc_node_trace+0x272/0x790 mm/slab.c:3593 __do_kmalloc_node mm/slab.c:3615 [inline] __kmalloc_node+0x38/0x60 mm/slab.c:3623 kmalloc_node include/linux/slab.h:578 [inline] kvmalloc_node+0x61/0xf0 mm/util.c:574 kvmalloc include/linux/mm.h:645 [inline] kvzalloc include/linux/mm.h:653 [inline] bucket_table_alloc+0x8b/0x480 lib/rhashtable.c:175 rhashtable_init+0x3d2/0x750 lib/rhashtable.c:1054 nf_flow_table_init+0x16d/0x310 net/netfilter/nf_flow_table_core.c:498 tcf_ct_flow_table_get+0xe33/0x1700 net/sched/act_ct.c:82 tcf_ct_init+0xba4/0x18a6 net/sched/act_ct.c:1050 tcf_action_init_1+0x697/0xa20 net/sched/act_api.c:945 tcf_action_init+0x1e9/0x2f0 net/sched/act_api.c:1001 tcf_action_add+0xdb/0x370 net/sched/act_api.c:1411 tc_ctl_action+0x366/0x456 net/sched/act_api.c:1466 rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5440 netlink_rcv_skb+0x15a/0x410 net/netlink/af_netlink.c:2478 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline] netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329 netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6b9/0x7d0 net/socket.c:2343 ___sys_sendmsg+0x100/0x170 net/socket.c:2397 __sys_sendmsg+0xec/0x1b0 net/socket.c:2430 do_syscall_64+0xf6/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4403d9 Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffd719af218 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004403d9 RDX: 0000000000000000 RSI: 0000000020000300 RDI: 0000000000000003 RBP: 00000000006ca018 R08: 0000000000000005 R09: 00000000004002c8 R10: 0000000000000008 R11: 00000000000 Fixes: c34b961a2492 ("net/sched: act_ct: Create nf flow table per zone") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Paul Blakey <paulb@mellanox.com> Cc: Jiri Pirko <jiri@mellanox.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.