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Hou Tao
e6b1a44ecc
The __this_cpu*() accessors are (in general) IRQ-unsafe which, given
that percpu-rwsem is a blocking primitive, should be just fine.
However, file_end_write() is used from IRQ context and will cause
load-store issues on architectures where the per-cpu accessors are not
natively irq-safe.
Fix it by using the IRQ-safe this_cpu_*() for operations on
read_count. This will generate more expensive code on a number of
platforms, which might cause a performance regression for some of the
other percpu-rwsem users.
If any such is reported, we can consider alternative solutions.
Fixes: 70fe2f4815 ("aio: fix freeze protection of aio writes")
Signed-off-by: Hou Tao <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Will Deacon <[email protected]>
Acked-by: Oleg Nesterov <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]