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Taehee Yoo e1f469cd58 Revert "netns: don't disable BHs when locking "nsid_lock"" This reverts commit `8d7e5dee97`. To protect netns id, the nsid_lock is used when netns id is being allocated and removed by peernet2id_alloc() and unhash_nsid(). The nsid_lock can be used in BH context but only spin_lock() is used in this code. Using spin_lock() instead of spin_lock_bh() can result in a deadlock in the following scenario reported by the lockdep. In order to avoid a deadlock, the spin_lock_bh() should be used instead of spin_lock() to acquire nsid_lock. Test commands: ip netns del nst ip netns add nst ip link add veth1 type veth peer name veth2 ip link set veth1 netns nst ip netns exec nst ip link add name br1 type bridge vlan_filtering 1 ip netns exec nst ip link set dev br1 up ip netns exec nst ip link set dev veth1 master br1 ip netns exec nst ip link set dev veth1 up ip netns exec nst ip link add macvlan0 link br1 up type macvlan Splat looks like: [ 33.615860][ T607] WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected [ 33.617194][ T607] 5.9.0-rc1+ #665 Not tainted [ ... ] [ 33.670615][ T607] Chain exists of: [ 33.670615][ T607] &mc->mca_lock --> &bridge_netdev_addr_lock_key --> &net->nsid_lock [ 33.670615][ T607] [ 33.673118][ T607] Possible interrupt unsafe locking scenario: [ 33.673118][ T607] [ 33.674599][ T607] CPU0 CPU1 [ 33.675557][ T607] ---- ---- [ 33.676516][ T607] lock(&net->nsid_lock); [ 33.677306][ T607] local_irq_disable(); [ 33.678517][ T607] lock(&mc->mca_lock); [ 33.679725][ T607] lock(&bridge_netdev_addr_lock_key); [ 33.681166][ T607] <Interrupt> [ 33.681791][ T607] lock(&mc->mca_lock); [ 33.682579][ T607] [ 33.682579][ T607] * DEADLOCK * [ ... ] [ 33.922046][ T607] stack backtrace: [ 33.922999][ T607] CPU: 3 PID: 607 Comm: ip Not tainted 5.9.0-rc1+ #665 [ 33.924099][ T607] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 [ 33.925714][ T607] Call Trace: [ 33.926238][ T607] dump_stack+0x78/0xab [ 33.926905][ T607] check_irq_usage+0x70b/0x720 [ 33.927708][ T607] ? iterate_chain_key+0x60/0x60 [ 33.928507][ T607] ? check_path+0x22/0x40 [ 33.929201][ T607] ? check_noncircular+0xcf/0x180 [ 33.930024][ T607] ? __lock_acquire+0x1952/0x1f20 [ 33.930860][ T607] __lock_acquire+0x1952/0x1f20 [ 33.931667][ T607] lock_acquire+0xaf/0x3a0 [ 33.932366][ T607] ? peernet2id_alloc+0x3a/0x170 [ 33.933147][ T607] ? br_port_fill_attrs+0x54c/0x6b0 [bridge] [ 33.934140][ T607] ? br_port_fill_attrs+0x5de/0x6b0 [bridge] [ 33.935113][ T607] ? kvm_sched_clock_read+0x14/0x30 [ 33.935974][ T607] _raw_spin_lock+0x30/0x70 [ 33.936728][ T607] ? peernet2id_alloc+0x3a/0x170 [ 33.937523][ T607] peernet2id_alloc+0x3a/0x170 [ 33.938313][ T607] rtnl_fill_ifinfo+0xb5e/0x1400 [ 33.939091][ T607] rtmsg_ifinfo_build_skb+0x8a/0xf0 [ 33.939953][ T607] rtmsg_ifinfo_event.part.39+0x17/0x50 [ 33.940863][ T607] rtmsg_ifinfo+0x1f/0x30 [ 33.941571][ T607] __dev_notify_flags+0xa5/0xf0 [ 33.942376][ T607] ? __irq_work_queue_local+0x49/0x50 [ 33.943249][ T607] ? irq_work_queue+0x1d/0x30 [ 33.943993][ T607] ? __dev_set_promiscuity+0x7b/0x1a0 [ 33.944878][ T607] __dev_set_promiscuity+0x7b/0x1a0 [ 33.945758][ T607] dev_set_promiscuity+0x1e/0x50 [ 33.946582][ T607] br_port_set_promisc+0x1f/0x40 [bridge] [ 33.947487][ T607] br_manage_promisc+0x8b/0xe0 [bridge] [ 33.948388][ T607] __dev_set_promiscuity+0x123/0x1a0 [ 33.949244][ T607] __dev_set_rx_mode+0x68/0x90 [ 33.950021][ T607] dev_uc_add+0x50/0x60 [ 33.950720][ T607] macvlan_open+0x18e/0x1f0 [macvlan] [ 33.951601][ T607] __dev_open+0xd6/0x170 [ 33.952269][ T607] __dev_change_flags+0x181/0x1d0 [ 33.953056][ T607] rtnl_configure_link+0x2f/0xa0 [ 33.953884][ T607] __rtnl_newlink+0x6b9/0x8e0 [ 33.954665][ T607] ? __lock_acquire+0x95d/0x1f20 [ 33.955450][ T607] ? lock_acquire+0xaf/0x3a0 [ 33.956193][ T607] ? is_bpf_text_address+0x5/0xe0 [ 33.956999][ T607] rtnl_newlink+0x47/0x70 Acked-by: Guillaume Nault <gnault@redhat.com> Fixes: `8d7e5dee97` ("netns: don't disable BHs when locking "nsid_lock"") Reported-by: syzbot+3f960c64a104eaa2c813@syzkaller.appspotmail.com Signed-off-by: Taehee Yoo <ap420073@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>		2020-09-07 14:32:39 -07:00
arch	s390 fixes for 5.9-rc4	2020-09-04 13:46:33 -07:00
block	block-5.9-2020-09-04	2020-09-04 13:04:51 -07:00
certs	.gitignore: add SPDX License Identifier	2020-03-25 11:50:48 +01:00
crypto	Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6	2020-08-30 15:53:44 -07:00
Documentation	Kbuild fixes for v5.9 (2nd)	2020-09-04 13:34:52 -07:00
drivers	ibmvnic: add missing parenthesis in do_reset()	2020-09-07 14:03:11 -07:00
fs	io_uring-5.9-2020-09-04	2020-09-04 12:55:22 -07:00
include	netdevice.h: fix xdp_state kernel-doc warning	2020-09-07 12:46:58 -07:00
init	init: fix error check in clean_path()	2020-09-04 09:16:58 -07:00
ipc	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
kernel	gcov: Disable gcov build with GCC 10	2020-09-04 09:19:49 -07:00
lib	lib: Revert use of fallthrough pseudo-keyword in lib/	2020-08-24 14:17:44 -07:00
LICENSES	LICENSES: Rename other to deprecated	2019-05-03 06:34:32 -06:00
mm	Merge branch 'simplify-do_wp_page'	2020-09-04 09:31:54 -07:00
net	Revert "netns: don't disable BHs when locking "nsid_lock""	2020-09-07 14:32:39 -07:00
samples	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
scripts	kconfig: remove redundant assignment prompt = prompt	2020-09-03 12:21:22 +09:00
security	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
sound	sound fixes for 5.9-rc4	2020-09-04 12:05:25 -07:00
tools	perf tools fixes for v5.9: 2nd batch	2020-09-03 19:10:43 -07:00
usr	Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2020-08-07 13:29:39 -07:00
virt	* PAE and PKU bugfixes for x86	2020-08-22 10:03:05 -07:00
.clang-format	block: add bio_for_each_bvec_all()	2020-05-25 11:25:24 +02:00
.cocciconfig
.get_maintainer.ignore	Opt out of scripts/get_maintainer.pl	2019-05-16 10:53:40 -07:00
.gitattributes	.gitattributes: use 'dts' diff driver for dts files	2019-12-04 19:44:11 -08:00
.gitignore	.gitignore: Add ZSTD-compressed files	2020-07-31 11:50:49 +02:00
.mailmap	Merge branch 'akpm' (patches from Andrew)	2020-08-21 14:44:48 -07:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	CREDITS: Replace HTTP links with HTTPS ones	2020-07-23 14:53:58 -06:00
Kbuild	kbuild: rename hostprogs-y/always to hostprogs/always-y	2020-02-04 01:53:07 +09:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net	2020-09-03 18:50:48 -07:00
Makefile	Linux 5.9-rc3	2020-08-30 16:01:54 -07:00
README	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00

README

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.