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regulator: push allocation in regulator_ena_gpio_request() out of lock 

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: 541d052d72 ("regulator: core: Only support passing enable GPIO descriptors")
[this commit only changes context]
Fixes: f8702f9e4a ("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>
Link: https://lore.kernel.org/r/41fe6a9670335721b48e8f5195038c3d67a3bf92.1597195321.git.mirq-linux@rere.qmqm.pl
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Michał Mirosław 2020-08-12 03:31:34 +02:00 committed by Mark Brown
parent 73a32129f8
commit 467bf30142
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
1 changed files with 14 additions and 5 deletions
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19
drivers/regulator/core.c
View File

@ -2230,10 +2230,13 @@ 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(&regulator_list_mutex);
list_for_each_entry(pin, &regulator_ena_gpio_list, list) {
if (pin->gpiod == gpiod) {
@ -2242,9 +2245,13 @@ 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(&regulator_list_mutex);
return -ENOMEM;
}
pin = new_pin;
new_pin = NULL;
pin->gpiod = gpiod;
list_add(&pin->list, &regulator_ena_gpio_list);
@ -2252,6 +2259,10 @@ static int regulator_ena_gpio_request(struct regulator_dev *rdev,
update_ena_gpio_to_rdev:
pin->request_count++;
rdev->ena_pin = pin;
mutex_unlock(&regulator_list_mutex);
kfree(new_pin);
return 0;
}
@ -5209,9 +5220,7 @@ regulator_register(const struct regulator_desc *regulator_desc,
}
if (config->ena_gpiod) {
mutex_lock(&regulator_list_mutex);
ret = regulator_ena_gpio_request(rdev, config);
mutex_unlock(&regulator_list_mutex);
if (ret != 0) {
rdev_err(rdev, "Failed to request enable GPIO: %d\n",
ret);