From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Guanghui Feng <guanghuifeng@linux.alibaba.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sasha Levin <sashal@kernel.org>,
jslaby@suse.com
Subject: [PATCH AUTOSEL 4.14 08/14] tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc
Date: Tue, 9 Nov 2021 17:23:37 -0500 [thread overview]
Message-ID: <20211109222343.1235902-8-sashal@kernel.org> (raw)
In-Reply-To: <20211109222343.1235902-1-sashal@kernel.org>
From: Guanghui Feng <guanghuifeng@linux.alibaba.com>
[ 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>
---
drivers/tty/tty_buffer.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index cf11882d26025..a5b32dd056bef 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -528,6 +528,9 @@ static void flush_to_ldisc(struct work_struct *work)
if (!count)
break;
head->read += count;
+
+ if (need_resched())
+ cond_resched();
}
mutex_unlock(&buf->lock);
--
2.33.0
next prev parent reply other threads:[~2021-11-09 22:43 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-09 22:23 [PATCH AUTOSEL 4.14 01/14] arm64: zynqmp: Fix serial compatible string Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 02/14] scsi: lpfc: Fix list_add() corruption in lpfc_drain_txq() Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 03/14] arm64: dts: rockchip: add Coresight debug range for RK3399 Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 04/14] usb: musb: tusb6010: check return value after calling platform_get_resource() Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 05/14] scsi: advansys: Fix kernel pointer leak Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 06/14] ARM: dts: omap: fix gpmc,mux-add-data type Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 07/14] usb: host: ohci-tmio: check return value after calling platform_get_resource() Sasha Levin
2021-11-09 22:23 ` Sasha Levin [this message]
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 09/14] MIPS: sni: Fix the build Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 10/14] scsi: target: Fix ordered tag handling Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 11/14] scsi: target: Fix alua_tg_pt_gps_count tracking Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 12/14] powerpc/5200: dts: fix memory node unit name Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 13/14] ALSA: gus: fix null pointer dereference on pointer block Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 14/14] powerpc/dcr: Use cmplwi instead of 3-argument cmpli Sasha Levin
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