From: Geliang Tang <tanggeliang@kylinos.cn>
I got the following error when running bpf burst sched selftests in auto-btf-debug mode:
[ 167.258293][ T49] BUG: sleeping function called from invalid context at net/core/sock.c:3652
[ 167.258981][ T49] in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 49, name: kworker/0:2
[ 167.259547][ T49] preempt_count: 0, expected: 0
[ 167.259826][ T49] RCU nest depth: 1, expected: 0
[ 167.259975][ T49] 5 locks held by kworker/0:2/49:
[ 167.260137][ T49] #0: ffff888001130948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7e4/0x16b0
[ 167.260741][ T49] #1: ffffc90000347d90 ((work_completion)(&msk->work)){+.+.}-{0:0}, at: process_one_work+0xdf9/0x16b0
[ 167.261206][ T49] #2: ffff88800c620e58 (sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_worker+0x7b/0xad0
[ 167.261476][ T49] #3: ffffffff8977e620 (rcu_read_lock){....}-{1:2}, at: __bpf_prog_enter+0x1f/0x170
[ 167.261742][ T49] #4: ffff88800b6f8258 (k-sk_lock-AF_INET#2){+.+.}-{0:0}, at: bpf_prog_87e3c1bd65224f1c_bpf_burst_get_subflow+0x12c/0x58b
[ 167.262309][ T49] CPU: 0 UID: 0 PID: 49 Comm: kworker/0:2 Tainted: G OE 6.12.0-rc6+ #9
[ 167.262591][ T49] Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
[ 167.262774][ T49] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 167.262950][ T49] Workqueue: events mptcp_worker
[ 167.263097][ T49] Call Trace:
[ 167.263211][ T49] <TASK>
[ 167.263301][ T49] dump_stack_lvl+0x9e/0xe0
[ 167.263453][ T49] __might_resched+0x35d/0x590
[ 167.263599][ T49] ? __pfx___might_resched+0x10/0x10
[ 167.263829][ T49] __lock_sock_fast+0x2f/0xd0
[ 167.264035][ T49] mptcp_pm_nl_subflow_chk_stale+0x1e2/0x3c0
[ 167.264304][ T49] ? bpf_prog_87e3c1bd65224f1c_bpf_burst_get_subflow+0x12c/0x58b
[ 167.264604][ T49] bpf_prog_87e3c1bd65224f1c_bpf_burst_get_subflow+0x12c/0x58b
[ 167.264995][ T49] ? mptcp_sched_get_retrans+0x1f8/0x330
[ 167.265215][ T49] ? __pfx_mptcp_sched_get_retrans+0x10/0x10
[ 167.265432][ T49] ? mark_lock+0x371/0x3c0
[ 167.265678][ T49] ? __mptcp_retrans+0xf4/0x9a0
[ 167.265973][ T49] ? mptcp_worker+0x7b/0xad0
mptcp_pm_subflow_chk_stale is a sleeping function, it shouldn't be
invoked under BPF rcu_read_lock.
One solution is to set mptcp_pm_subflow_chk_stale with KF_SLEEPABLE
flag:
BTF_ID_FLAGS(func, mptcp_pm_subflow_chk_stale, KF_SLEEPABLE)
Then set bpf_burst_get_subflow with BPF_F_SLEEPABLE:
err = bpf_program__set_flags(skel->progs.bpf_burst_get_subflow,
BPF_F_SLEEPABLE);
But another error ocurrs:
[ 101.732098][ C0] BUG: sleeping function called from invalid context at kernel/bpf/trampoline.c:968
[ 101.732781][ C0] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1640, name: test_progs-no_a
[ 101.733477][ C0] preempt_count: 303, expected: 0
[ 101.733793][ C0] RCU nest depth: 2, expected: 0
[ 101.734043][ C0] 6 locks held by test_progs-no_a/1640:
[ 101.734187][ C0] #0: ffff888007526e58 (sk_lock-AF_INET){+.+.}-{0:0}, at: sk_wait_data (net/core/sock.c:3131 (discriminator 2))
[ 101.734440][ C0] #1: ffffffff95b7e620 (rcu_read_lock){....}-{1:2}, at: process_backlog (include/linux/local_lock_internal.h:38 (discriminator 1) net/core/dev.c:6115 (discriminator 1))
[ 101.734728][ C0] #2: ffffffff95b7e620 (rcu_read_lock){....}-{1:2}, at: ip_local_deliver_finish (include/linux/rcupdate.h:337 (discriminator 1) include/linux/rcupdate.h:849 (discriminator 1) net/ipv4/ip_input.c:232 (discriminator 1))
[ 101.735103][ C0] #3: ffff888008eb8e58 (k-slock-AF_INET/1){+.-.}-{2:2}, at: tcp_v4_rcv (include/linux/skbuff.h:1670 include/net/tcp.h:2530 net/ipv4/tcp_ipv4.c:2348)
[ 101.735560][ C0] #4: ffff8880075261d8 (slock-AF_INET){+.-.}-{2:2}, at: mptcp_incoming_options (net/mptcp/options.c:1053 net/mptcp/options.c:1203)
[ 101.736023][ C0] #5: ffffffff95b7d980 (rcu_read_lock_trace){....}-{0:0}, at: __bpf_prog_enter_sleepable (include/linux/rcupdate.h:337 (discriminator 1) include/linux/rcupdate_trace.h:57 (discriminator 1) kernel/bpf/trampoline.c:966 (discriminator 1))
[ 101.736325][ C0] CPU: 0 UID: 0 PID: 1640 Comm: test_progs-no_a Tainted: G OE 6.12.0-rc7+ #5
[ 101.736676][ C0] Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
[ 101.736940][ C0] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 101.737146][ C0] Call Trace:
[ 101.737259][ C0] <IRQ>
[ 101.737331][ C0] dump_stack_lvl (lib/dump_stack.c:123)
[ 101.737489][ C0] __might_resched (kernel/sched/core.c:8657)
[ 101.737625][ C0] ? __lock_acquire (kernel/locking/lockdep.c:5202 (discriminator 1))
[ 101.737772][ C0] ? __pfx___might_resched (kernel/sched/core.c:8611)
[ 101.737919][ C0] __might_fault (mm/memory.c:6715 (discriminator 1))
[ 101.738051][ C0] __bpf_prog_enter_sleepable (include/linux/bpf.h:2089 (discriminator 1) kernel/bpf/trampoline.c:970 (discriminator 1))
[ 101.738195][ C0] ? __bpf_prog_enter_sleepable (include/linux/rcupdate.h:337 (discriminator 1) include/linux/rcupdate_trace.h:57 (discriminator 1) kernel/bpf/trampoline.c:966 (discriminator 1))
[ 101.738357][ C0] ? mptcp_sched_get_send (net/mptcp/sched.c:183)
[ 101.738511][ C0] ? __pfx_mptcp_sched_get_send (net/mptcp/sched.c:158)
[ 101.738641][ C0] ? __bpf_tramp_enter (include/linux/rcupdate.h:347 (discriminator 1) include/linux/rcupdate.h:880 (discriminator 1) include/linux/percpu-refcount.h:209 (discriminator 1) include/linux/percpu-refcount.h:222 (discriminator 1) kernel/bpf/trampoline.c:1010 (discriminator 1))
[ 101.738774][ C0] ? bpf_trampoline_6442561300+0x31/0xd7
[ 101.738911][ C0] ? mptcp_sched_get_send (net/mptcp/sched.c:158)
[ 101.739067][ C0] ? __mptcp_subflow_push_pending (net/mptcp/protocol.c:1682 (discriminator 1))
[ 101.739231][ C0] ? __pfx___mptcp_subflow_push_pending (net/mptcp/protocol.c:1655)
[ 101.739378][ C0] ? do_raw_spin_lock (arch/x86/include/asm/atomic.h:107 (discriminator 1) include/linux/atomic/atomic-arch-fallback.h:2170 (discriminator 1) include/linux/atomic/atomic-instrumented.h:1302 (discriminator 1) include/asm-generic/qspinlock.h:111 (discriminator 1) kernel/locking/spinlock_debug.c:116 (discriminator 1))
[ 101.739556][ C0] ? __pfx_do_raw_spin_lock (kernel/locking/spinlock_debug.c:114)
[ 101.739743][ C0] ? mptcp_incoming_options (net/mptcp/options.c:1067 net/mptcp/options.c:1203)
This means get_send() interface of this scheduler can't be set with
BPF_F_SLEEPABLE flag since it's invoked in ack_update_msk() under mptcp
data lock.
So this patch has to split get_subflow() interface of packet scheduer into
two interfaces: get_send() and get_retrans(). Then we can set get_retrans()
interface alone with BPF_F_SLEEPABLE flag.
Thanks to Barry for helping me solve this issue.
Cc: Barry Song <baohua@kernel.org>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/529
Geliang Tang (8):
mptcp: split get_subflow interface into two
Squash to "selftests/bpf: Add bpf_first scheduler & test"
Squash to "selftests/bpf: Add bpf_bkup scheduler & test"
Squash to "selftests/bpf: Add bpf_rr scheduler & test"
Squash to "selftests/bpf: Add bpf_red scheduler & test"
Squash to "selftests/bpf: Add bpf_burst scheduler & test"
Squash to "bpf: Export mptcp packet scheduler helpers"
Squash to "selftests/bpf: Add bpf_burst scheduler & test"
include/net/mptcp.h | 5 +--
net/mptcp/bpf.c | 13 ++++++--
net/mptcp/sched.c | 33 ++++++++++++-------
.../testing/selftests/bpf/prog_tests/mptcp.c | 14 ++++++--
.../selftests/bpf/progs/mptcp_bpf_bkup.c | 24 +++++++++++---
.../selftests/bpf/progs/mptcp_bpf_burst.c | 32 ++++++++----------
.../selftests/bpf/progs/mptcp_bpf_first.c | 24 +++++++++++---
.../selftests/bpf/progs/mptcp_bpf_red.c | 24 +++++++++++---
.../selftests/bpf/progs/mptcp_bpf_rr.c | 24 +++++++++++---
9 files changed, 136 insertions(+), 57 deletions(-)
--
2.43.0