Jonathan Lemon 1f63b3393b bpf: Save correct stopping point in file seq iteration ... [ Upstream commit 69ca310f34168eae0ada434796bfc22fb4a0fa26 ] On some systems, some variant of the following splat is repeatedly seen. The common factor in all traces seems to be the entry point to task_file_seq_next(). With the patch, all warnings go away. rcu: INFO: rcu_sched self-detected stall on CPU rcu: \x0926-....: (20992 ticks this GP) idle=d7e/1/0x4000000000000002 softirq=81556231/81556231 fqs=4876 \x09(t=21033 jiffies g=159148529 q=223125) NMI backtrace for cpu 26 CPU: 26 PID: 2015853 Comm: bpftool Kdump: loaded Not tainted 5.6.13-0_fbk4_3876_gd8d1f9bf80bb #1 Hardware name: Quanta Twin Lakes MP/Twin Lakes Passive MP, BIOS F09_3A12 10/08/2018 Call Trace: <IRQ> dump_stack+0x50/0x70 nmi_cpu_backtrace.cold.6+0x13/0x50 ? lapic_can_unplug_cpu.cold.30+0x40/0x40 nmi_trigger_cpumask_backtrace+0xba/0xca rcu_dump_cpu_stacks+0x99/0xc7 rcu_sched_clock_irq.cold.90+0x1b4/0x3aa ? tick_sched_do_timer+0x60/0x60 update_process_times+0x24/0x50 tick_sched_timer+0x37/0x70 __hrtimer_run_queues+0xfe/0x270 hrtimer_interrupt+0xf4/0x210 smp_apic_timer_interrupt+0x5e/0x120 apic_timer_interrupt+0xf/0x20 </IRQ> RIP: 0010:get_pid_task+0x38/0x80 Code: 89 f6 48 8d 44 f7 08 48 8b 00 48 85 c0 74 2b 48 83 c6 55 48 c1 e6 04 48 29 f0 74 19 48 8d 78 20 ba 01 00 00 00 f0 0f c1 50 20 <85> d2 74 27 78 11 83 c2 01 78 0c 48 83 c4 08 c3 31 c0 48 83 c4 08 RSP: 0018:ffffc9000d293dc8 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13 RAX: ffff888637c05600 RBX: ffffc9000d293e0c RCX: 0000000000000000 RDX: 0000000000000001 RSI: 0000000000000550 RDI: ffff888637c05620 RBP: ffffffff8284eb80 R08: ffff88831341d300 R09: ffff88822ffd8248 R10: ffff88822ffd82d0 R11: 00000000003a93c0 R12: 0000000000000001 R13: 00000000ffffffff R14: ffff88831341d300 R15: 0000000000000000 ? find_ge_pid+0x1b/0x20 task_seq_get_next+0x52/0xc0 task_file_seq_get_next+0x159/0x220 task_file_seq_next+0x4f/0xa0 bpf_seq_read+0x159/0x390 vfs_read+0x8a/0x140 ksys_read+0x59/0xd0 do_syscall_64+0x42/0x110 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f95ae73e76e Code: Bad RIP value. RSP: 002b:00007ffc02c1dbf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 000000000170faa0 RCX: 00007f95ae73e76e RDX: 0000000000001000 RSI: 00007ffc02c1dc30 RDI: 0000000000000007 RBP: 00007ffc02c1ec70 R08: 0000000000000005 R09: 0000000000000006 R10: fffffffffffff20b R11: 0000000000000246 R12: 00000000019112a0 R13: 0000000000000000 R14: 0000000000000007 R15: 00000000004283c0 If unable to obtain the file structure for the current task, proceed to the next task number after the one returned from task_seq_get_next(), instead of the next task number from the original iterator. Also, save the stopping task number from task_seq_get_next() on failure in case of restarts. Fixes: eaaacd2391 ("bpf: Add task and task/file iterator targets") Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20201218185032.2464558-2-jonathan.lemon@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org>		2021-01-19 18:27:28 +01:00
..
preload	bpf: BPF_PRELOAD depends on BPF_SYSCALL	2020-11-05 18:49:29 -08:00
arraymap.c	bpf: Allow for map-in-map with dynamic inner array map entries	2020-10-11 10:21:04 -07:00
bpf_inode_storage.c	bpf: Allow specifying a BTF ID per argument in function protos	2020-09-21 15:00:40 -07:00
bpf_iter.c	bpf: Bump iter seq size to support BTF representation of large data structures	2020-09-28 18:26:58 -07:00
bpf_local_storage.c	bpf: Use hlist_add_head_rcu when linking to local_storage	2020-09-19 01:12:35 +02:00
bpf_lru_list.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206	2019-05-30 11:29:53 -07:00
bpf_lru_list.h	bpf: Fix a typo "inacitve" -> "inactive"	2020-04-06 21:54:10 +02:00
bpf_lsm.c	bpf: Update verification logic for LSM programs	2020-11-06 13:15:21 -08:00
bpf_struct_ops_types.h	bpf: tcp: Support tcp_congestion_ops in bpf	2020-01-09 08:46:18 -08:00
bpf_struct_ops.c	bpf: Move btf_resolve_size into __btf_resolve_size	2020-08-25 15:37:41 -07:00
btf.c	bpf: Introduce bpf_per_cpu_ptr()	2020-10-02 15:00:49 -07:00
cgroup.c	Merge branch 'work.set_fs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2020-10-22 09:59:21 -07:00
core.c	bpf: Don't rely on GCC __attribute__((optimize)) to disable GCSE	2020-10-29 20:01:46 -07:00
cpumap.c	bpf, cpumap: Remove rcpu pointer from cpu_map_build_skb signature	2020-09-28 23:30:42 +02:00
devmap.c	bpf: {cpu,dev}map: Change various functions return type from int to void	2020-09-01 15:45:58 +02:00
disasm.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295	2019-06-05 17:36:38 +02:00
disasm.h	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295	2019-06-05 17:36:38 +02:00
dispatcher.c	bpf: Remove bpf_image tree	2020-03-13 12:49:52 -07:00
hashtab.c	bpf: Zero-fill re-used per-cpu map element	2020-11-05 19:55:57 -08:00
helpers.c	bpf: Fix enum names for bpf_this_cpu_ptr() and bpf_per_cpu_ptr() helpers	2020-12-11 14:19:07 -08:00
inode.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net	2020-09-22 16:45:34 -07:00
local_storage.c	bpf/local_storage: Fix build without CONFIG_CGROUP	2020-07-25 20:16:36 -07:00
lpm_trie.c	bpf: Add map_meta_equal map ops	2020-08-28 15:41:30 +02:00
Makefile	bpf: Don't rely on GCC __attribute__((optimize)) to disable GCSE	2020-10-29 20:01:46 -07:00
map_in_map.c	bpf: Relax max_entries check for most of the inner map types	2020-08-28 15:41:30 +02:00
map_in_map.h	bpf: Add map_meta_equal map ops	2020-08-28 15:41:30 +02:00
map_iter.c	bpf: Implement link_query callbacks in map element iterators	2020-08-21 14:01:39 -07:00
net_namespace.c	bpf: Add support for forced LINK_DETACH command	2020-08-01 20:38:28 -07:00
offload.c	bpf, offload: Replace bitwise AND by logical AND in bpf_prog_offload_info_fill	2020-02-17 16:53:49 +01:00
percpu_freelist.c	bpf: Use raw_spin_trylock() for pcpu_freelist_push/pop in NMI	2020-10-06 00:04:11 +02:00
percpu_freelist.h	bpf: Use raw_spin_trylock() for pcpu_freelist_push/pop in NMI	2020-10-06 00:04:11 +02:00
prog_iter.c	bpf: Refactor bpf_iter_reg to have separate seq_info member	2020-07-25 20:16:32 -07:00
queue_stack_maps.c	bpf: Add map_meta_equal map ops	2020-08-28 15:41:30 +02:00
reuseport_array.c	bpf, net: Rework cookie generator as per-cpu one	2020-09-30 11:50:35 -07:00
ringbuf.c	bpf: Add map_meta_equal map ops	2020-08-28 15:41:30 +02:00
stackmap.c	bpf: Allow specifying a BTF ID per argument in function protos	2020-09-21 15:00:40 -07:00
syscall.c	bpf: Remove unneeded break	2020-10-19 20:40:21 +02:00
sysfs_btf.c	bpf: Fix sysfs export of empty BTF section	2020-09-21 21:50:24 +02:00
task_iter.c	bpf: Save correct stopping point in file seq iteration	2021-01-19 18:27:28 +01:00
tnum.c	bpf: Verifier, do explicit ALU32 bounds tracking	2020-03-30 14:59:53 -07:00
trampoline.c	bpf: Move prog->aux->linked_prog and trampoline into bpf_link on attach	2020-09-29 13:09:23 -07:00
verifier.c	bpf: Fix propagation of 32-bit signed bounds from 64-bit bounds.	2020-12-10 13:02:53 -08:00