From: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>
To: Dmitry Osipenko <digetx@gmail.com>,
Liam Girdwood <lgirdwood@gmail.com>,
Mark Brown <broonie@kernel.org>
Cc: linux-kernel@vger.kernel.org, Vladimir Zapolskiy <vz@mleia.com>
Subject: [PATCH 2/7] regulator: push allocation in regulator_ena_gpio_request() out of lock
Date: Tue, 11 Aug 2020 03:07:38 +0200 [thread overview]
Message-ID: <a45e2e0715171228f140a0a01cc5924c5379bfa3.1597107682.git.mirq-linux@rere.qmqm.pl> (raw)
In-Reply-To: <cover.1597107682.git.mirq-linux@rere.qmqm.pl>
Move another allocation out of regulator_list_mutex-protected region, as
reclaim might want to take the same lock.
WARNING: possible circular locking dependency detected
5.7.13+ #534 Not tainted
------------------------------------------------------
kswapd0/383 is trying to acquire lock:
c0e5d920 (regulator_list_mutex){+.+.}-{3:3}, at: regulator_lock_dependent+0x54/0x2c0
but task is already holding lock:
c0e38518 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x0/0x50
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (fs_reclaim){+.+.}-{0:0}:
fs_reclaim_acquire.part.11+0x40/0x50
fs_reclaim_acquire+0x24/0x28
kmem_cache_alloc_trace+0x40/0x1e8
regulator_register+0x384/0x1630
devm_regulator_register+0x50/0x84
reg_fixed_voltage_probe+0x248/0x35c
[...]
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(regulator_list_mutex);
lock(fs_reclaim);
lock(regulator_list_mutex);
*** DEADLOCK ***
[...]
2 locks held by kswapd0/383:
#0: c0e38518 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x0/0x50
#1: cb70e5e0 (hctx->srcu){....}-{0:0}, at: hctx_lock+0x60/0xb8
[...]
Fixes: 541d052d7215 ("regulator: core: Only support passing enable GPIO descriptors")
[this commit only changes context]
Fixes: f8702f9e4aa7 ("regulator: core: Use ww_mutex for regulators locking")
[this is when the regulator_list_mutex was introduced in reclaim locking path]
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
---
drivers/regulator/core.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 510d234f6c46..3dd4d4914075 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -2203,10 +2203,13 @@ EXPORT_SYMBOL_GPL(regulator_bulk_unregister_supply_alias);
static int regulator_ena_gpio_request(struct regulator_dev *rdev,
const struct regulator_config *config)
{
- struct regulator_enable_gpio *pin;
+ struct regulator_enable_gpio *pin, *new_pin;
struct gpio_desc *gpiod;
gpiod = config->ena_gpiod;
+ new_pin = kzalloc(sizeof(*new_pin), GFP_KERNEL);
+
+ mutex_lock(®ulator_list_mutex);
list_for_each_entry(pin, ®ulator_ena_gpio_list, list) {
if (pin->gpiod == gpiod) {
@@ -2215,9 +2218,13 @@ static int regulator_ena_gpio_request(struct regulator_dev *rdev,
}
}
- pin = kzalloc(sizeof(struct regulator_enable_gpio), GFP_KERNEL);
- if (pin == NULL)
+ if (new_pin == NULL) {
+ mutex_unlock(®ulator_list_mutex);
return -ENOMEM;
+ }
+
+ pin = new_pin;
+ new_pin = NULL;
pin->gpiod = gpiod;
list_add(&pin->list, ®ulator_ena_gpio_list);
@@ -2225,6 +2232,10 @@ static int regulator_ena_gpio_request(struct regulator_dev *rdev,
update_ena_gpio_to_rdev:
pin->request_count++;
rdev->ena_pin = pin;
+
+ mutex_unlock(®ulator_list_mutex);
+ kfree(new_pin);
+
return 0;
}
@@ -5179,9 +5190,7 @@ regulator_register(const struct regulator_desc *regulator_desc,
}
if (config->ena_gpiod) {
- mutex_lock(®ulator_list_mutex);
ret = regulator_ena_gpio_request(rdev, config);
- mutex_unlock(®ulator_list_mutex);
if (ret != 0) {
rdev_err(rdev, "Failed to request enable GPIO: %d\n",
ret);
--
2.20.1
next prev parent reply other threads:[~2020-08-11 1:08 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-11 1:07 [PATCH 0/7] regulator: fix deadlock vs memory reclaim Michał Mirosław
2020-08-11 1:07 ` [PATCH 1/7] regulator: push allocation in regulator_init_coupling() outside of lock Michał Mirosław
2020-08-11 15:59 ` Dmitry Osipenko
2020-08-11 16:27 ` Dmitry Osipenko
2020-08-11 17:20 ` Michał Mirosław
2020-08-11 21:02 ` Dmitry Osipenko
2020-08-11 1:07 ` [PATCH 3/7] regulator: push allocations in create_regulator() " Michał Mirosław
2020-08-11 1:07 ` Michał Mirosław [this message]
2020-08-11 1:07 ` [PATCH 4/7] regulator: push allocation in set_consumer_device_supply() out " Michał Mirosław
2020-08-11 5:23 ` kernel test robot
2020-08-11 17:28 ` Michał Mirosław
2020-08-11 1:07 ` [PATCH 6/7] regulator: cleanup regulator_ena_gpio_free() Michał Mirosław
2020-08-11 1:07 ` [PATCH 5/7] regulator: plug of_node leak in regulator_register()'s error path Michał Mirosław
2020-08-11 6:15 ` Vladimir Zapolskiy
2020-08-11 1:07 ` [PATCH 7/7] regulator: remove superfluous lock in regulator_resolve_coupling() Michał Mirosław
2020-08-11 15:56 ` Dmitry Osipenko
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