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Filename Latest commit message Latest commit date
Wen Gu f82013d1d6 net/smc: Avoid warning of possible recursive locking
[ Upstream commit 7a61432dc81375be06b02f0061247d3efbdfce3a ]

Possible recursive locking is detected by lockdep when SMC
falls back to TCP. The corresponding warnings are as follows:

 ============================================
 WARNING: possible recursive locking detected
 5.16.0-rc1+ #18 Tainted: G            E
 --------------------------------------------
 wrk/1391 is trying to acquire lock:
 ffff975246c8e7d8 (&ei->socket.wq.wait){..-.}-{3:3}, at: smc_switch_to_fallback+0x109/0x250 [smc]

 but task is already holding lock:
 ffff975246c8f918 (&ei->socket.wq.wait){..-.}-{3:3}, at: smc_switch_to_fallback+0xfe/0x250 [smc]

 other info that might help us debug this:
  Possible unsafe locking scenario:

        CPU0
        ----
   lock(&ei->socket.wq.wait);
   lock(&ei->socket.wq.wait);

  *** DEADLOCK ***

  May be due to missing lock nesting notation

 2 locks held by wrk/1391:
  #0: ffff975246040130 (sk_lock-AF_SMC){+.+.}-{0:0}, at: smc_connect+0x43/0x150 [smc]
  #1: ffff975246c8f918 (&ei->socket.wq.wait){..-.}-{3:3}, at: smc_switch_to_fallback+0xfe/0x250 [smc]

 stack backtrace:
 Call Trace:
  <TASK>
  dump_stack_lvl+0x56/0x7b
  __lock_acquire+0x951/0x11f0
  lock_acquire+0x27a/0x320
  ? smc_switch_to_fallback+0x109/0x250 [smc]
  ? smc_switch_to_fallback+0xfe/0x250 [smc]
  _raw_spin_lock_irq+0x3b/0x80
  ? smc_switch_to_fallback+0x109/0x250 [smc]
  smc_switch_to_fallback+0x109/0x250 [smc]
  smc_connect_fallback+0xe/0x30 [smc]
  __smc_connect+0xcf/0x1090 [smc]
  ? mark_held_locks+0x61/0x80
  ? __local_bh_enable_ip+0x77/0xe0
  ? lockdep_hardirqs_on+0xbf/0x130
  ? smc_connect+0x12a/0x150 [smc]
  smc_connect+0x12a/0x150 [smc]
  __sys_connect+0x8a/0xc0
  ? syscall_enter_from_user_mode+0x20/0x70
  __x64_sys_connect+0x16/0x20
  do_syscall_64+0x34/0x90
  entry_SYSCALL_64_after_hwframe+0x44/0xae

The nested locking in smc_switch_to_fallback() is considered to
possibly cause a deadlock because smc_wait->lock and clc_wait->lock
are the same type of lock. But actually it is safe so far since
there is no other place trying to obtain smc_wait->lock when
clc_wait->lock is held. So the patch replaces spin_lock() with
spin_lock_nested() to avoid false report by lockdep.

Link: https://lkml.org/lkml/2021/11/19/962
Fixes: 2153bd1e3d3d ("Transfer remaining wait queue entries during fallback")
Reported-by: syzbot+e979d3597f48262cb4ee@syzkaller.appspotmail.com
Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Acked-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-12-08 09:01:10 +01:00
arch s390/setup: avoid using memblock_enforce_memory_limit 2021-12-08 09:01:09 +01:00
block block: remove inaccurate requeue check 2021-11-17 09:48:31 +01:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:47:29 +02:00
crypto crypto: pcrypt - Delay write to padata->info 2021-11-17 09:48:40 +01:00
Documentation netfilter: ipvs: Fix reuse connection if RS weight is 0 2021-12-01 09:23:31 +01:00
drivers net: ethernet: dec: tulip: de4x5: fix possible array overflows in type3_infoblock() 2021-12-08 09:01:10 +01:00
fs btrfs: check-integrity: fix a warning on write caching disabled disk 2021-12-08 09:01:09 +01:00
include of: clk: Make <linux/of_clk.h> self-contained 2021-12-08 09:01:08 +01:00
init
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-12-01 09:23:35 +01:00
kernel tracing: Check pid filtering when creating events 2021-12-01 09:23:34 +01:00
lib lib/xz: Validate the value before assigning it to an enum variable 2021-11-17 09:48:31 +01:00
LICENSES
mm hugetlbfs: flush TLBs correctly after huge_pmd_unshare 2021-11-26 10:47:23 +01:00
net net/smc: Avoid warning of possible recursive locking 2021-12-08 09:01:10 +01:00
samples samples/kretprobes: Fix return value if register_kretprobe() failed 2021-11-17 09:48:39 +01:00
scripts leaking_addresses: Always print a trailing newline 2021-11-17 09:48:31 +01:00
security fortify: Explicitly disable Clang support 2021-11-21 13:38:50 +01:00
sound ASoC: topology: Add missing rwsem around snd_ctl_remove() calls 2021-12-01 09:23:32 +01:00
tools perf report: Fix memory leaks around perf_tip() 2021-12-08 09:01:10 +01:00
usr
virt KVM: do not shrink halt_poll_ns below grow_start 2021-10-09 14:39:50 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.163 2021-12-01 09:23:36 +01:00
README

Linux kernel
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There are various text files in the Documentation/ subdirectory,
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Please read the Documentation/process/changes.rst file, as it contains the
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