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authorPavel Begunkov <asml.silence@gmail.com>2021-08-10 02:44:23 +0100
committerJens Axboe <axboe@kernel.dk>2021-08-09 19:59:28 -0600
commit43597aac1f87230cb565ab354d331682f13d3c7a (patch)
treea5d8303429c786df465bfe988bac84e266d4900c /fs
parentc018db4a57f3e31a9cb24d528e9f094eda89a499 (diff)
io_uring: fix ctx-exit io_rsrc_put_work() deadlock
__io_rsrc_put_work() might need ->uring_lock, so nobody should wait for rsrc nodes holding the mutex. However, that's exactly what io_ring_ctx_free() does with io_wait_rsrc_data(). Split it into rsrc wait + dealloc, and move the first one out of the lock. Cc: stable@vger.kernel.org Fixes: b60c8dce33895 ("io_uring: preparation for rsrc tagging") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/0130c5c2693468173ec1afab714e0885d2c9c363.1628559783.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
-rw-r--r--fs/io_uring.c15
1 files changed, 8 insertions, 7 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 0c3e90f974e9..04c6d059ea94 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8652,13 +8652,10 @@ static void io_req_caches_free(struct io_ring_ctx *ctx)
mutex_unlock(&ctx->uring_lock);
}
-static bool io_wait_rsrc_data(struct io_rsrc_data *data)
+static void io_wait_rsrc_data(struct io_rsrc_data *data)
{
- if (!data)
- return false;
- if (!atomic_dec_and_test(&data->refs))
+ if (data && !atomic_dec_and_test(&data->refs))
wait_for_completion(&data->done);
- return true;
}
static void io_ring_ctx_free(struct io_ring_ctx *ctx)
@@ -8670,10 +8667,14 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
ctx->mm_account = NULL;
}
+ /* __io_rsrc_put_work() may need uring_lock to progress, wait w/o it */
+ io_wait_rsrc_data(ctx->buf_data);
+ io_wait_rsrc_data(ctx->file_data);
+
mutex_lock(&ctx->uring_lock);
- if (io_wait_rsrc_data(ctx->buf_data))
+ if (ctx->buf_data)
__io_sqe_buffers_unregister(ctx);
- if (io_wait_rsrc_data(ctx->file_data))
+ if (ctx->file_data)
__io_sqe_files_unregister(ctx);
if (ctx->rings)
__io_cqring_overflow_flush(ctx, true);