* [PATCH AUTOSEL 4.14 05/53] serial: set suppress_bind_attrs flag only if builtin
[not found] <20190108193222.123316-1-sashal@kernel.org>
@ 2019-01-08 19:31 ` Sasha Levin
2019-01-08 19:32 ` [PATCH AUTOSEL 4.14 33/53] tty/serial: do not free trasnmit buffer page under port lock Sasha Levin
1 sibling, 0 replies; 2+ messages in thread
From: Sasha Levin @ 2019-01-08 19:31 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Anders Roxell, Arnd Bergmann, Greg Kroah-Hartman, Sasha Levin,
linux-serial
From: Anders Roxell <anders.roxell@linaro.org>
[ Upstream commit 646097940ad35aa2c1f2012af932d55976a9f255 ]
When the test 'CONFIG_DEBUG_TEST_DRIVER_REMOVE=y' is enabled,
arch_initcall(pl011_init) came before subsys_initcall(default_bdi_init).
devtmpfs gets killed because we try to remove a file and decrement the
wb reference count before the noop_backing_device_info gets initialized.
[ 0.332075] Serial: AMBA PL011 UART driver
[ 0.485276] 9000000.pl011: ttyAMA0 at MMIO 0x9000000 (irq = 39, base_baud = 0) is a PL011 rev1
[ 0.502382] console [ttyAMA0] enabled
[ 0.515710] Unable to handle kernel paging request at virtual address 0000800074c12000
[ 0.516053] Mem abort info:
[ 0.516222] ESR = 0x96000004
[ 0.516417] Exception class = DABT (current EL), IL = 32 bits
[ 0.516641] SET = 0, FnV = 0
[ 0.516826] EA = 0, S1PTW = 0
[ 0.516984] Data abort info:
[ 0.517149] ISV = 0, ISS = 0x00000004
[ 0.517339] CM = 0, WnR = 0
[ 0.517553] [0000800074c12000] user address but active_mm is swapper
[ 0.517928] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[ 0.518305] Modules linked in:
[ 0.518839] CPU: 0 PID: 13 Comm: kdevtmpfs Not tainted 4.19.0-rc5-next-20180928-00002-g2ba39ab0cd01-dirty #82
[ 0.519307] Hardware name: linux,dummy-virt (DT)
[ 0.519681] pstate: 80000005 (Nzcv daif -PAN -UAO)
[ 0.519959] pc : __destroy_inode+0x94/0x2a8
[ 0.520212] lr : __destroy_inode+0x78/0x2a8
[ 0.520401] sp : ffff0000098c3b20
[ 0.520590] x29: ffff0000098c3b20 x28: 00000000087a3714
[ 0.520904] x27: 0000000000002000 x26: 0000000000002000
[ 0.521179] x25: ffff000009583000 x24: 0000000000000000
[ 0.521467] x23: ffff80007bb52000 x22: ffff80007bbaa7c0
[ 0.521737] x21: ffff0000093f9338 x20: 0000000000000000
[ 0.522033] x19: ffff80007bbb05d8 x18: 0000000000000400
[ 0.522376] x17: 0000000000000000 x16: 0000000000000000
[ 0.522727] x15: 0000000000000400 x14: 0000000000000400
[ 0.523068] x13: 0000000000000001 x12: 0000000000000001
[ 0.523421] x11: 0000000000000000 x10: 0000000000000970
[ 0.523749] x9 : ffff0000098c3a60 x8 : ffff80007bbab190
[ 0.524017] x7 : ffff80007bbaa880 x6 : 0000000000000c88
[ 0.524305] x5 : ffff0000093d96c8 x4 : 61c8864680b583eb
[ 0.524567] x3 : ffff0000093d6180 x2 : ffffffffffffffff
[ 0.524872] x1 : 0000800074c12000 x0 : 0000800074c12000
[ 0.525207] Process kdevtmpfs (pid: 13, stack limit = 0x(____ptrval____))
[ 0.525529] Call trace:
[ 0.525806] __destroy_inode+0x94/0x2a8
[ 0.526108] destroy_inode+0x34/0x88
[ 0.526370] evict+0x144/0x1c8
[ 0.526636] iput+0x184/0x230
[ 0.526871] dentry_unlink_inode+0x118/0x130
[ 0.527152] d_delete+0xd8/0xe0
[ 0.527420] vfs_unlink+0x240/0x270
[ 0.527665] handle_remove+0x1d8/0x330
[ 0.527875] devtmpfsd+0x138/0x1c8
[ 0.528085] kthread+0x14c/0x158
[ 0.528291] ret_from_fork+0x10/0x18
[ 0.528720] Code: 92800002 aa1403e0 d538d081 8b010000 (c85f7c04)
[ 0.529367] ---[ end trace 5a3dee47727f877c ]---
Rework to set suppress_bind_attrs flag to avoid removing the device when
CONFIG_DEBUG_TEST_DRIVER_REMOVE=y. This applies for pic32_uart and
xilinx_uartps as well.
Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/amba-pl011.c | 2 ++
drivers/tty/serial/pic32_uart.c | 1 +
drivers/tty/serial/xilinx_uartps.c | 1 +
3 files changed, 4 insertions(+)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index c9f701aca677..4a4a9f33715c 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2800,6 +2800,7 @@ static struct platform_driver arm_sbsa_uart_platform_driver = {
.name = "sbsa-uart",
.of_match_table = of_match_ptr(sbsa_uart_of_match),
.acpi_match_table = ACPI_PTR(sbsa_uart_acpi_match),
+ .suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_AMBA_PL011),
},
};
@@ -2828,6 +2829,7 @@ static struct amba_driver pl011_driver = {
.drv = {
.name = "uart-pl011",
.pm = &pl011_dev_pm_ops,
+ .suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_AMBA_PL011),
},
.id_table = pl011_ids,
.probe = pl011_probe,
diff --git a/drivers/tty/serial/pic32_uart.c b/drivers/tty/serial/pic32_uart.c
index 00a33eb859d3..e3d7d9d6c599 100644
--- a/drivers/tty/serial/pic32_uart.c
+++ b/drivers/tty/serial/pic32_uart.c
@@ -920,6 +920,7 @@ static struct platform_driver pic32_uart_platform_driver = {
.driver = {
.name = PIC32_DEV_NAME,
.of_match_table = of_match_ptr(pic32_serial_dt_ids),
+ .suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_PIC32),
},
};
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 21c35ad72b99..772d07f85b3d 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1644,6 +1644,7 @@ static struct platform_driver cdns_uart_platform_driver = {
.name = CDNS_UART_NAME,
.of_match_table = cdns_uart_of_match,
.pm = &cdns_uart_dev_pm_ops,
+ .suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_XILINX_PS_UART),
},
};
--
2.19.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* [PATCH AUTOSEL 4.14 33/53] tty/serial: do not free trasnmit buffer page under port lock
[not found] <20190108193222.123316-1-sashal@kernel.org>
2019-01-08 19:31 ` [PATCH AUTOSEL 4.14 05/53] serial: set suppress_bind_attrs flag only if builtin Sasha Levin
@ 2019-01-08 19:32 ` Sasha Levin
1 sibling, 0 replies; 2+ messages in thread
From: Sasha Levin @ 2019-01-08 19:32 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Sergey Senozhatsky, Sergey Senozhatsky, Greg Kroah-Hartman,
Jiri Slaby, Andrew Morton, Waiman Long, Dmitry Safonov,
Steven Rostedt, Sasha Levin, linux-serial
From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
[ 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 6db8844ef3ec..543d0f95f094 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -218,10 +218,15 @@ 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) {
@@ -281,6 +286,7 @@ 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
@@ -311,14 +317,18 @@ 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
^ permalink raw reply related [flat|nested] 2+ messages in thread