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From: Jens Axboe <axboe@kernel.dk>
To: io-uring <io-uring@vger.kernel.org>
Subject: [PATCH] io-wq: cancel work if we fail getting a mm reference
Date: Tue, 14 Jan 2020 22:11:09 -0700
Message-ID: <654cbd24-d056-6f23-ceda-e2e77ea5650d@kernel.dk> (raw)

If we require mm and user context, mark the request for cancellation
if we fail to acquire the desired mm.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io-wq.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 541c8a3e0bbb..5147d2213b01 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -445,10 +445,14 @@ static void io_worker_handle_work(struct io_worker *worker)
 			task_unlock(current);
 		}
 		if ((work->flags & IO_WQ_WORK_NEEDS_USER) && !worker->mm &&
-		    wq->mm && mmget_not_zero(wq->mm)) {
-			use_mm(wq->mm);
-			set_fs(USER_DS);
-			worker->mm = wq->mm;
+		    wq->mm) {
+			if (mmget_not_zero(wq->mm)) {
+				use_mm(wq->mm);
+				set_fs(USER_DS);
+				worker->mm = wq->mm;
+			} else {
+				work->flags |= IO_WQ_WORK_CANCEL;
+			}
 		}
 		if (!worker->creds)
 			worker->creds = override_creds(wq->creds);
-- 
2.25.0

-- 
Jens Axboe


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