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Taehee Yoo 3f167e1921 gtp: fix Illegal context switch in RCU read-side critical section.
ipv4_pdp_add() is called in RCU read-side critical section.
So GFP_KERNEL should not be used in the function.
This patch make ipv4_pdp_add() to use GFP_ATOMIC instead of GFP_KERNEL.

Test commands:
gtp-link add gtp1 &
gtp-tunnel add gtp1 v1 100 200 1.1.1.1 2.2.2.2

Splat looks like:
[  130.618881] =============================
[  130.626382] WARNING: suspicious RCU usage
[  130.626994] 5.2.0-rc6+ #50 Not tainted
[  130.627622] -----------------------------
[  130.628223] ./include/linux/rcupdate.h:266 Illegal context switch in RCU read-side critical section!
[  130.629684]
[  130.629684] other info that might help us debug this:
[  130.629684]
[  130.631022]
[  130.631022] rcu_scheduler_active = 2, debug_locks = 1
[  130.632136] 4 locks held by gtp-tunnel/1025:
[  130.632925]  #0: 000000002b93c8b7 (cb_lock){++++}, at: genl_rcv+0x15/0x40
[  130.634159]  #1: 00000000f17bc999 (genl_mutex){+.+.}, at: genl_rcv_msg+0xfb/0x130
[  130.635487]  #2: 00000000c644ed8e (rtnl_mutex){+.+.}, at: gtp_genl_new_pdp+0x18c/0x1150 [gtp]
[  130.636936]  #3: 0000000007a1cde7 (rcu_read_lock){....}, at: gtp_genl_new_pdp+0x187/0x1150 [gtp]
[  130.638348]
[  130.638348] stack backtrace:
[  130.639062] CPU: 1 PID: 1025 Comm: gtp-tunnel Not tainted 5.2.0-rc6+ #50
[  130.641318] Call Trace:
[  130.641707]  dump_stack+0x7c/0xbb
[  130.642252]  ___might_sleep+0x2c0/0x3b0
[  130.642862]  kmem_cache_alloc_trace+0x1cd/0x2b0
[  130.643591]  gtp_genl_new_pdp+0x6c5/0x1150 [gtp]
[  130.644371]  genl_family_rcv_msg+0x63a/0x1030
[  130.645074]  ? mutex_lock_io_nested+0x1090/0x1090
[  130.645845]  ? genl_unregister_family+0x630/0x630
[  130.646592]  ? debug_show_all_locks+0x2d0/0x2d0
[  130.647293]  ? check_flags.part.40+0x440/0x440
[  130.648099]  genl_rcv_msg+0xa3/0x130
[ ... ]

Fixes: 459aa660eb ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-07-07 18:42:47 -07:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2019-07-03 12:09:00 -07:00
block block: fix page leak when merging to same page 2019-06-17 09:33:04 -06:00
certs treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
crypto treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
Documentation Documentation/networking: fix default_ttl typo in mpls-sysctl 2019-07-01 10:41:33 -07:00
drivers gtp: fix Illegal context switch in RCU read-side critical section. 2019-07-07 18:42:47 -07:00
fs for-linus-20190627 2019-06-28 08:41:18 +08:00
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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.