The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 7839d0078e0d5e6cc2fa0b0dfbee71de74f1e557 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024012620-panhandle-mushiness-a8c4@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

7839d0078e0d ("PM: sleep: Fix possible deadlocks in core system-wide PM code") 73d73f5ee7fb ("PM: core: Remove unnecessary (void *) conversions")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7839d0078e0d5e6cc2fa0b0dfbee71de74f1e557 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" rafael.j.wysocki@intel.com Date: Wed, 27 Dec 2023 21:41:06 +0100 Subject: [PATCH] PM: sleep: Fix possible deadlocks in core system-wide PM code

It is reported that in low-memory situations the system-wide resume core code deadlocks, because async_schedule_dev() executes its argument function synchronously if it cannot allocate memory (and not only in that case) and that function attempts to acquire a mutex that is already held. Executing the argument function synchronously from within dpm_async_fn() may also be problematic for ordering reasons (it may cause a consumer device's resume callback to be invoked before a requisite supplier device's one, for example).

Address this by changing the code in question to use async_schedule_dev_nocall() for scheduling the asynchronous execution of device suspend and resume functions and to directly run them synchronously if async_schedule_dev_nocall() returns false.

Link: https://lore.kernel.org/linux-pm/ZYvjiqX6EsL15moe@perf/ Reported-by: Youngmin Nam youngmin.nam@samsung.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Reviewed-by: Stanislaw Gruszka stanislaw.gruszka@linux.intel.com Tested-by: Youngmin Nam youngmin.nam@samsung.com Reviewed-by: Ulf Hansson ulf.hansson@linaro.org Cc: 5.7+ stable@vger.kernel.org # 5.7+: 6aa09a5bccd8 async: Split async_schedule_node_domain() Cc: 5.7+ stable@vger.kernel.org # 5.7+: 7d4b5d7a37bd async: Introduce async_schedule_dev_nocall() Cc: 5.7+ stable@vger.kernel.org # 5.7+

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c index f85f3515c258..9c5a5f4dba5a 100644 --- a/drivers/base/power/main.c +++ b/drivers/base/power/main.c @@ -579,7 +579,7 @@ bool dev_pm_skip_resume(struct device *dev) }

/** - * device_resume_noirq - Execute a "noirq resume" callback for given device. + * __device_resume_noirq - Execute a "noirq resume" callback for given device. * @dev: Device to handle. * @state: PM transition of the system being carried out. * @async: If true, the device is being resumed asynchronously. @@ -587,7 +587,7 @@ bool dev_pm_skip_resume(struct device *dev) * The driver of @dev will not receive interrupts while this function is being * executed. */ -static int device_resume_noirq(struct device *dev, pm_message_t state, bool async) +static void __device_resume_noirq(struct device *dev, pm_message_t state, bool async) { pm_callback_t callback = NULL; const char *info = NULL; @@ -655,7 +655,13 @@ static int device_resume_noirq(struct device *dev, pm_message_t state, bool asyn Out: complete_all(&dev->power.completion); TRACE_RESUME(error); - return error; + + if (error) { + suspend_stats.failed_resume_noirq++; + dpm_save_failed_step(SUSPEND_RESUME_NOIRQ); + dpm_save_failed_dev(dev_name(dev)); + pm_dev_err(dev, state, async ? " async noirq" : " noirq", error); + } }

static bool is_async(struct device *dev) @@ -668,11 +674,15 @@ static bool dpm_async_fn(struct device *dev, async_func_t func) { reinit_completion(&dev->power.completion);

- if (is_async(dev)) { - get_device(dev); - async_schedule_dev(func, dev); + if (!is_async(dev)) + return false; + + get_device(dev); + + if (async_schedule_dev_nocall(func, dev)) return true; - } + + put_device(dev);

return false; } @@ -680,15 +690,19 @@ static bool dpm_async_fn(struct device *dev, async_func_t func) static void async_resume_noirq(void *data, async_cookie_t cookie) { struct device *dev = data; - int error; - - error = device_resume_noirq(dev, pm_transition, true); - if (error) - pm_dev_err(dev, pm_transition, " async", error);

+ __device_resume_noirq(dev, pm_transition, true); put_device(dev); }

+static void device_resume_noirq(struct device *dev) +{ + if (dpm_async_fn(dev, async_resume_noirq)) + return; + + __device_resume_noirq(dev, pm_transition, false); +} + static void dpm_noirq_resume_devices(pm_message_t state) { struct device *dev; @@ -698,14 +712,6 @@ static void dpm_noirq_resume_devices(pm_message_t state) mutex_lock(&dpm_list_mtx); pm_transition = state;

- /* - * Advanced the async threads upfront, - * in case the starting of async threads is - * delayed by non-async resuming devices. - */ - list_for_each_entry(dev, &dpm_noirq_list, power.entry) - dpm_async_fn(dev, async_resume_noirq); - while (!list_empty(&dpm_noirq_list)) { dev = to_device(dpm_noirq_list.next); get_device(dev); @@ -713,17 +719,7 @@ static void dpm_noirq_resume_devices(pm_message_t state)

mutex_unlock(&dpm_list_mtx);

- if (!is_async(dev)) { - int error; - - error = device_resume_noirq(dev, state, false); - if (error) { - suspend_stats.failed_resume_noirq++; - dpm_save_failed_step(SUSPEND_RESUME_NOIRQ); - dpm_save_failed_dev(dev_name(dev)); - pm_dev_err(dev, state, " noirq", error); - } - } + device_resume_noirq(dev);

put_device(dev);

@@ -751,14 +747,14 @@ void dpm_resume_noirq(pm_message_t state) }

/** - * device_resume_early - Execute an "early resume" callback for given device. + * __device_resume_early - Execute an "early resume" callback for given device. * @dev: Device to handle. * @state: PM transition of the system being carried out. * @async: If true, the device is being resumed asynchronously. * * Runtime PM is disabled for @dev while this function is being executed. */ -static int device_resume_early(struct device *dev, pm_message_t state, bool async) +static void __device_resume_early(struct device *dev, pm_message_t state, bool async) { pm_callback_t callback = NULL; const char *info = NULL; @@ -811,21 +807,31 @@ static int device_resume_early(struct device *dev, pm_message_t state, bool asyn

pm_runtime_enable(dev); complete_all(&dev->power.completion); - return error; + + if (error) { + suspend_stats.failed_resume_early++; + dpm_save_failed_step(SUSPEND_RESUME_EARLY); + dpm_save_failed_dev(dev_name(dev)); + pm_dev_err(dev, state, async ? " async early" : " early", error); + } }

static void async_resume_early(void *data, async_cookie_t cookie) { struct device *dev = data; - int error; - - error = device_resume_early(dev, pm_transition, true); - if (error) - pm_dev_err(dev, pm_transition, " async", error);

+ __device_resume_early(dev, pm_transition, true); put_device(dev); }

+static void device_resume_early(struct device *dev) +{ + if (dpm_async_fn(dev, async_resume_early)) + return; + + __device_resume_early(dev, pm_transition, false); +} + /** * dpm_resume_early - Execute "early resume" callbacks for all devices. * @state: PM transition of the system being carried out. @@ -839,14 +845,6 @@ void dpm_resume_early(pm_message_t state) mutex_lock(&dpm_list_mtx); pm_transition = state;

- /* - * Advanced the async threads upfront, - * in case the starting of async threads is - * delayed by non-async resuming devices. - */ - list_for_each_entry(dev, &dpm_late_early_list, power.entry) - dpm_async_fn(dev, async_resume_early); - while (!list_empty(&dpm_late_early_list)) { dev = to_device(dpm_late_early_list.next); get_device(dev); @@ -854,17 +852,7 @@ void dpm_resume_early(pm_message_t state)

mutex_unlock(&dpm_list_mtx);

- if (!is_async(dev)) { - int error; - - error = device_resume_early(dev, state, false); - if (error) { - suspend_stats.failed_resume_early++; - dpm_save_failed_step(SUSPEND_RESUME_EARLY); - dpm_save_failed_dev(dev_name(dev)); - pm_dev_err(dev, state, " early", error); - } - } + device_resume_early(dev);

put_device(dev);

@@ -888,12 +876,12 @@ void dpm_resume_start(pm_message_t state) EXPORT_SYMBOL_GPL(dpm_resume_start);

/** - * device_resume - Execute "resume" callbacks for given device. + * __device_resume - Execute "resume" callbacks for given device. * @dev: Device to handle. * @state: PM transition of the system being carried out. * @async: If true, the device is being resumed asynchronously. */ -static int device_resume(struct device *dev, pm_message_t state, bool async) +static void __device_resume(struct device *dev, pm_message_t state, bool async) { pm_callback_t callback = NULL; const char *info = NULL; @@ -975,20 +963,30 @@ static int device_resume(struct device *dev, pm_message_t state, bool async)

TRACE_RESUME(error);

- return error; + if (error) { + suspend_stats.failed_resume++; + dpm_save_failed_step(SUSPEND_RESUME); + dpm_save_failed_dev(dev_name(dev)); + pm_dev_err(dev, state, async ? " async" : "", error); + } }

static void async_resume(void *data, async_cookie_t cookie) { struct device *dev = data; - int error;

- error = device_resume(dev, pm_transition, true); - if (error) - pm_dev_err(dev, pm_transition, " async", error); + __device_resume(dev, pm_transition, true); put_device(dev); }

+static void device_resume(struct device *dev) +{ + if (dpm_async_fn(dev, async_resume)) + return; + + __device_resume(dev, pm_transition, false); +} + /** * dpm_resume - Execute "resume" callbacks for non-sysdev devices. * @state: PM transition of the system being carried out. @@ -1008,27 +1006,17 @@ void dpm_resume(pm_message_t state) pm_transition = state; async_error = 0;

- list_for_each_entry(dev, &dpm_suspended_list, power.entry) - dpm_async_fn(dev, async_resume); - while (!list_empty(&dpm_suspended_list)) { dev = to_device(dpm_suspended_list.next); + get_device(dev); - if (!is_async(dev)) { - int error;

- mutex_unlock(&dpm_list_mtx); + mutex_unlock(&dpm_list_mtx); + + device_resume(dev);

- error = device_resume(dev, state, false); - if (error) { - suspend_stats.failed_resume++; - dpm_save_failed_step(SUSPEND_RESUME); - dpm_save_failed_dev(dev_name(dev)); - pm_dev_err(dev, state, "", error); - } + mutex_lock(&dpm_list_mtx);

- mutex_lock(&dpm_list_mtx); - } if (!list_empty(&dev->power.entry)) list_move_tail(&dev->power.entry, &dpm_prepared_list);