io-wq: fix race between adding work and activating a free worker

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The attempt to find and activate a free worker for new work is currently
combined with creating a new one if we don't find one, but that opens
io-wq up to a race where the worker that is found and activated can
put itself to sleep without knowing that it has been selected to perform
this new work.

Fix this by moving the activation into where we add the new work item,
then we can retain it within the wqe->lock scope and elimiate the race
with the worker itself checking inside the lock, but sleeping outside of
it.

Cc: stable@vger.kernel.org
Reported-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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This commit is contained in:

Jens Axboe 2021-08-30 11:55:22 -06:00

parent 87df7fb922

commit 94ffb0a282

1 changed files with 24 additions and 27 deletions

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fs/io-wq.c

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