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David Howells 608aecd16a rxrpc: Fix locking issues in rxrpc_put_peer_locked()
Now that rxrpc_put_local() may call kthread_stop(), it can't be called
under spinlock as it might sleep.  This can cause a problem in the peer
keepalive code in rxrpc as it tries to avoid dropping the peer_hash_lock
from the point it needs to re-add peer->keepalive_link to going round the
loop again in rxrpc_peer_keepalive_dispatch().

Fix this by just dropping the lock when we don't need it and accepting that
we'll have to take it again.  This code is only called about every 20s for
each peer, so not very often.

This allows rxrpc_put_peer_unlocked() to be removed also.

If triggered, this bug produces an oops like the following, as reproduced
by a syzbot reproducer for a different oops[1]:

BUG: sleeping function called from invalid context at kernel/sched/completion.c:101
...
RCU nest depth: 0, expected: 0
3 locks held by kworker/u9:0/50:
 #0: ffff88810e74a138 ((wq_completion)krxrpcd){+.+.}-{0:0}, at: process_one_work+0x294/0x636
 #1: ffff8881013a7e20 ((work_completion)(&rxnet->peer_keepalive_work)){+.+.}-{0:0}, at: process_one_work+0x294/0x636
 #2: ffff88817d366390 (&rxnet->peer_hash_lock){+.+.}-{2:2}, at: rxrpc_peer_keepalive_dispatch+0x2bd/0x35f
...
Call Trace:
 <TASK>
 dump_stack_lvl+0x4c/0x5f
 __might_resched+0x2cf/0x2f2
 __wait_for_common+0x87/0x1e8
 kthread_stop+0x14d/0x255
 rxrpc_peer_keepalive_dispatch+0x333/0x35f
 rxrpc_peer_keepalive_worker+0x2e9/0x449
 process_one_work+0x3c1/0x636
 worker_thread+0x25f/0x359
 kthread+0x1a6/0x1b5
 ret_from_fork+0x1f/0x30

Fixes: a275da62e8 ("rxrpc: Create a per-local endpoint receive queue and I/O thread")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/0000000000002b4a9f05ef2b616f@google.com/ [1]
Signed-off-by: David S. Miller <davem@davemloft.net>
History 2022-12-19 09:51:31 +00:00
arch Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
block for-6.2/block-2022-12-08 2022-12-13 10:43:59 -08:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto iov_iter work; most of that is about getting rid of 2022-12-12 18:29:54 -08:00
Documentation docs/bpf: Reword docs for BPF_MAP_TYPE_SK_STORAGE 2022-12-14 18:35:41 +01:00
drivers Merge branch '1GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/net-queue 2022-12-18 21:00:40 +00:00
fs EFI updates for v6.2: 2022-12-13 14:31:47 -08:00
include Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
init modules changes for v6.2-rc1 2022-12-13 14:05:39 -08:00
io_uring for-6.2/block-2022-12-08 2022-12-13 10:43:59 -08:00
ipc Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
kernel bpf: Resolve fext program type when checking map compatibility 2022-12-14 21:30:27 -08:00
lib Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm for-6.2/block-2022-12-08 2022-12-13 10:43:59 -08:00
net rxrpc: Fix locking issues in rxrpc_put_peer_locked() 2022-12-19 09:51:31 +00:00
rust rust: types: add Opaque type 2022-12-04 01:59:16 +01:00
samples Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
scripts Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
security integrity-v6.2 2022-12-13 14:22:50 -08:00
sound sound updates for 6.2-rc1 2022-12-13 11:27:26 -08:00
tools bpf-for-netdev 2022-12-16 10:41:56 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt Merge branch 'kvm-dwmw2-fixes' into HEAD 2022-11-23 18:59:45 -05:00
.clang-format printk changes for 6.2 2022-12-12 09:01:36 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: Cleanup DT Overlay intermediate files as appropriate 2022-11-18 14:45:30 -06:00
.mailmap Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
Makefile This was a not-too-busy cycle for documentation; highlights include: 2022-12-12 17:18:50 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.