From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Petr Mladek <pmladek@suse.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Jiri Slaby <jslaby@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
Waiman Long <longman@redhat.com>,
Dmitry Safonov <dima@arista.com>,
Steven Rostedt <rostedt@goodmis.org>,
Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 24/39] tty/serial: do not free trasnmit buffer page under port lock
Date: Thu, 24 Jan 2019 20:20:27 +0100 [thread overview]
Message-ID: <20190124190449.100953795@linuxfoundation.org> (raw)
In-Reply-To: <20190124190448.232316246@linuxfoundation.org>
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
[ Upstream commit d72402145ace0697a6a9e8e75a3de5bf3375f78d ]
LKP has hit yet another circular locking dependency between uart
console drivers and debugobjects [1]:
CPU0 CPU1
rhltable_init()
__init_work()
debug_object_init
uart_shutdown() /* db->lock */
/* uart_port->lock */ debug_print_object()
free_page() printk()
call_console_drivers()
debug_check_no_obj_freed() /* uart_port->lock */
/* db->lock */
debug_print_object()
So there are two dependency chains:
uart_port->lock -> db->lock
And
db->lock -> uart_port->lock
This particular circular locking dependency can be addressed in several
ways:
a) One way would be to move debug_print_object() out of db->lock scope
and, thus, break the db->lock -> uart_port->lock chain.
b) Another one would be to free() transmit buffer page out of db->lock
in UART code; which is what this patch does.
It makes sense to apply a) and b) independently: there are too many things
going on behind free(), none of which depend on uart_port->lock.
The patch fixes transmit buffer page free() in uart_shutdown() and,
additionally, in uart_port_startup() (as was suggested by Dmitry Safonov).
[1] https://lore.kernel.org/lkml/20181211091154.GL23332@shao2-debian/T/#u
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Dmitry Safonov <dima@arista.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/serial_core.c | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 53e6db8b0330..bcfdaf6ddbb2 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -195,10 +195,15 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
if (!state->xmit.buf) {
state->xmit.buf = (unsigned char *) page;
uart_circ_clear(&state->xmit);
+ uart_port_unlock(uport, flags);
} else {
+ uart_port_unlock(uport, flags);
+ /*
+ * Do not free() the page under the port lock, see
+ * uart_shutdown().
+ */
free_page(page);
}
- uart_port_unlock(uport, flags);
retval = uport->ops->startup(uport);
if (retval == 0) {
@@ -258,6 +263,7 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
struct uart_port *uport = uart_port_check(state);
struct tty_port *port = &state->port;
unsigned long flags = 0;
+ char *xmit_buf = NULL;
/*
* Set the TTY IO error marker
@@ -288,14 +294,18 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
tty_port_set_suspended(port, 0);
/*
- * Free the transmit buffer page.
+ * Do not free() the transmit buffer page under the port lock since
+ * this can create various circular locking scenarios. For instance,
+ * console driver may need to allocate/free a debug object, which
+ * can endup in printk() recursion.
*/
uart_port_lock(state, flags);
- if (state->xmit.buf) {
- free_page((unsigned long)state->xmit.buf);
- state->xmit.buf = NULL;
- }
+ xmit_buf = state->xmit.buf;
+ state->xmit.buf = NULL;
uart_port_unlock(uport, flags);
+
+ if (xmit_buf)
+ free_page((unsigned long)xmit_buf);
}
/**
--
2.19.1
next prev parent reply other threads:[~2019-01-24 20:05 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-24 19:20 [PATCH 4.9 00/39] 4.9.153-stable review Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 01/39] r8169: Add support for new Realtek Ethernet Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 02/39] ipv6: Consider sk_bound_dev_if when binding a socket to a v4 mapped address Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 03/39] ipv6: Take rcu_read_lock in __inet6_bind for mapped addresses Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 04/39] platform/x86: asus-wmi: Tell the EC the OS will handle the display off hotkey Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 05/39] e1000e: allow non-monotonic SYSTIM readings Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 06/39] writeback: dont decrement wb->refcnt if !wb->bdi Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 07/39] serial: set suppress_bind_attrs flag only if builtin Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 08/39] ALSA: oxfw: add support for APOGEE duet FireWire Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 09/39] MIPS: SiByte: Enable swiotlb for SWARM, LittleSur and BigSur Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 10/39] arm64: perf: set suppress_bind_attrs flag to true Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 11/39] selinux: always allow mounting submounts Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 12/39] rxe: IB_WR_REG_MR does not capture MRs iova field Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 13/39] jffs2: Fix use of uninitialized delayed_work, lockdep breakage Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 14/39] pstore/ram: Do not treat empty buffers as valid Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 15/39] powerpc/xmon: Fix invocation inside lock region Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 16/39] powerpc/pseries/cpuidle: Fix preempt warning Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 17/39] media: firewire: Fix app_info parameter type in avc_ca{,_app}_info Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 18/39] net: call sk_dst_reset when set SO_DONTROUTE Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 19/39] scsi: target: use consistent left-aligned ASCII INQUIRY data Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 20/39] clk: imx6q: reset exclusive gates on init Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 21/39] kconfig: fix file name and line number of warn_ignored_character() Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 22/39] kconfig: fix memory leak when EOF is encountered in quotation Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 23/39] mmc: atmel-mci: do not assume idle after atmci_request_end Greg Kroah-Hartman
2019-01-24 19:20 ` Greg Kroah-Hartman [this message]
2019-01-24 19:20 ` [PATCH 4.9 25/39] perf intel-pt: Fix error with config term "pt=0" Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 26/39] perf svghelper: Fix unchecked usage of strncpy() Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 27/39] perf parse-events: " Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 28/39] dm kcopyd: Fix bug causing workqueue stalls Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 29/39] tools lib subcmd: Dont add the kernel sources to the include path Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 30/39] dm snapshot: Fix excessive memory usage and workqueue stalls Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 31/39] ALSA: bebob: fix model-id of unit for Apogee Ensemble Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 32/39] sysfs: Disable lockdep for driver bind/unbind files Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 33/39] scsi: smartpqi: correct lun reset issues Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 34/39] scsi: megaraid: fix out-of-bound array accesses Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 35/39] ocfs2: fix panic due to unrecovered local alloc Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 36/39] mm/page-writeback.c: dont break integrity writeback on ->writepage() error Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 37/39] mm, proc: be more verbose about unstable VMA flags in /proc/<pid>/smaps Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 38/39] ipmi:ssif: Fix handling of multi-part return messages Greg Kroah-Hartman
2019-01-24 19:20 ` [PATCH 4.9 39/39] locking/qspinlock: Pull in asm/byteorder.h to ensure correct endianness Greg Kroah-Hartman
2019-01-25 14:43 ` [PATCH 4.9 00/39] 4.9.153-stable review shuah
2019-01-25 16:28 ` Naresh Kamboju
2019-01-25 23:17 ` Guenter Roeck
2019-01-26 12:07 ` Jon Hunter
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