Jens Axboe eaef83c4c0 eventfd: track eventfd_signal() recursion depth ... commit b5e683d5ca upstream. eventfd use cases from aio and io_uring can deadlock due to circular or resursive calling, when eventfd_signal() tries to grab the waitqueue lock. On top of that, it's also possible to construct notification chains that are deep enough that we could blow the stack. Add a percpu counter that tracks the percpu recursion depth, warn if we exceed it. The counter is also exposed so that users of eventfd_signal() can do the right thing if it's non-zero in the context where it is called. Cc: stable@vger.kernel.org # 4.19+ Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2020-02-11 04:34:08 -08:00
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acpi
asm-generic
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drm
dt-bindings
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kvm
linux	eventfd: track eventfd_signal() recursion depth	2020-02-11 04:34:08 -08:00
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