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FAILED: patch "[PATCH] io_uring: remove extra sqpoll submission halting" failed to apply to 5.11-stable tree

PATCH [email protected] 1 participant 1 message May 10, 2021

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The patch below does not apply to the 5.11-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3b763ba1c77da5806e4fdc5684285814fe970c98 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <[email protected]>
Date: Sun, 18 Apr 2021 14:52:08 +0100
Subject: [PATCH] io_uring: remove extra sqpoll submission halting

SQPOLL task won't submit requests for a context that is currently dying, so no need to remove ctx from sqd_list prior the main loop of io_ring_exit_work(). Kill it, will be removed by io_sq_thread_finish() and only brings confusion and lockups.

Cc [email protected]
Signed-off-by Pavel Begunkov <[email protected]>
Link https://lore.kernel.org/r/f220c2b786ba0f9499bebc9f3cd9714d29efb6a5.1618752958.git.asml.silence@gmail.com open here
Signed-off-by Jens Axboe <[email protected]>
fs/io_uring.c +4 -8
index e491b815df8c..4fc54cd40470 100644
@@ -6750,6 +6750,10 @@ static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
 		if (!list_empty(&ctx->iopoll_list))
 			io_do_iopoll(ctx, &nr_events, 0);
 
+		/*
+		 * Don't submit if refs are dying, good for io_uring_register(),
+		 * but also it is relied upon by io_ring_exit_work()
+		 */
 		if (to_submit && likely(!percpu_ref_is_dying(&ctx->refs)) &&
 		    !(ctx->flags & IORING_SETUP_R_DISABLED))
 			ret = io_submit_sqes(ctx, to_submit);

@@ -8540,14 +8544,6 @@ static void io_ring_exit_work(struct work_struct *work)
 	struct io_tctx_node *node;
 	int ret;
 
-	/* prevent SQPOLL from submitting new requests */
-	if (ctx->sq_data) {
-		io_sq_thread_park(ctx->sq_data);
-		list_del_init(&ctx->sqd_list);
-		io_sqd_update_thread_idle(ctx->sq_data);
-		io_sq_thread_unpark(ctx->sq_data);
-	}
-
 	/*
 	 * If we're doing polled IO and end up having requests being
 	 * submitted async (out-of-line), then completions can come in while