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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+:6aa09a5bccasync: Split async_schedule_node_domain() Cc: 5.7+ <stable@vger.kernel.org> # 5.7+:7d4b5d7a37async: Introduce async_schedule_dev_nocall() Cc: 5.7+ <stable@vger.kernel.org> # 5.7+
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.