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Filename Latest commit message Latest commit date
Guanghui Feng d491c84df5 tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc
[ Upstream commit 3968ddcf05fb4b9409cd1859feb06a5b0550a1c1 ]

When running ltp testcase(ltp/testcases/kernel/pty/pty04.c) with arm64, there is a soft lockup,
which look like this one:

  Workqueue: events_unbound flush_to_ldisc
  Call trace:
   dump_backtrace+0x0/0x1ec
   show_stack+0x24/0x30
   dump_stack+0xd0/0x128
   panic+0x15c/0x374
   watchdog_timer_fn+0x2b8/0x304
   __run_hrtimer+0x88/0x2c0
   __hrtimer_run_queues+0xa4/0x120
   hrtimer_interrupt+0xfc/0x270
   arch_timer_handler_phys+0x40/0x50
   handle_percpu_devid_irq+0x94/0x220
   __handle_domain_irq+0x88/0xf0
   gic_handle_irq+0x84/0xfc
   el1_irq+0xc8/0x180
   slip_unesc+0x80/0x214 [slip]
   tty_ldisc_receive_buf+0x64/0x80
   tty_port_default_receive_buf+0x50/0x90
   flush_to_ldisc+0xbc/0x110
   process_one_work+0x1d4/0x4b0
   worker_thread+0x180/0x430
   kthread+0x11c/0x120

In the testcase pty04, The first process call the write syscall to send
data to the pty master. At the same time, the workqueue will do the
flush_to_ldisc to pop data in a loop until there is no more data left.
When the sender and workqueue running in different core, the sender sends
data fastly in full time which will result in workqueue doing work in loop
for a long time and occuring softlockup in flush_to_ldisc with kernel
configured without preempt. So I add need_resched check and cond_resched
in the flush_to_ldisc loop to avoid it.

Signed-off-by: Guanghui Feng <guanghuifeng@linux.alibaba.com>
Link: https://lore.kernel.org/r/1633961304-24759-1-git-send-email-guanghuifeng@linux.alibaba.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-11-26 10:47:16 +01:00
arch ARM: dts: ls1021a-tsn: use generic "jedec,spi-nor" compatible for flash 2021-11-26 10:47:16 +01:00
block block: remove inaccurate requeue check 2021-11-17 09:48:31 +01:00
certs
crypto crypto: pcrypt - Delay write to padata->info 2021-11-17 09:48:40 +01:00
Documentation xen/balloon: add late_initcall_sync() for initial ballooning done 2021-11-17 09:48:25 +01:00
drivers tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc 2021-11-26 10:47:16 +01:00
fs erofs: fix unsafe pagevec reuse of hooked pclusters 2021-11-21 13:38:51 +01:00
include PCI/MSI: Deal with devices lying about their MSI mask capability 2021-11-21 13:38:50 +01:00
init
ipc
kernel PM: hibernate: fix sparse warnings 2021-11-17 09:48:39 +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 mm, oom: do not trigger out_of_memory from the #PF 2021-11-17 09:48:50 +01:00
net SUNRPC: Partial revert of commit 6f9f17287e78 2021-11-17 09:48:50 +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 ALSA: ISA: not for M68K 2021-11-26 10:47:16 +01:00
tools selftests/bpf: Fix also no-alu32 strobemeta selftest 2021-11-17 09:48:51 +01:00
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virt
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COPYING
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Kconfig
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Makefile Linux 5.4.161 2021-11-21 13:38:51 +01:00
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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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