io_uring/sqpoll: ensure normal task_work is also run timely

Bug: https://bugs.gentoo.org/931942

Signed-off-by: Mike Pagano <mpagano@gentoo.org>

2 files changed, 119 insertions, 0 deletions

diff --git a/0000_README b/0000_README
index 02b4c7fb..55885e7a 100644
--- a/0000_README
+++ b/0000_README
@@ -75,6 +75,10 @@ Patch:  2920_sign-file-patch-for-libressl.patch
 From:   https://bugs.gentoo.org/717166
 Desc:   sign-file: full functionality with modern LibreSSL
 
+Patch:  2930_io-uring-sqpoll-ensure-task_work-fix.patch
+From:   https://bugs.gentoo.org/931942
+Desc:   sqpoll: ensure that normal task_work is also run timely
+
 Patch:  3000_Support-printing-firmware-info.patch
 From:   https://bugs.gentoo.org/732852
 Desc:   Print firmware info (Reqs CONFIG_GENTOO_PRINT_FIRMWARE_INFO). Thanks to Georgy Yakovlev
diff --git a/2930_io-uring-sqpoll-ensure-task_work-fix.patch b/2930_io-uring-sqpoll-ensure-task_work-fix.patch
new file mode 100644
index 00000000..70e62a25
--- /dev/null
+++ b/2930_io-uring-sqpoll-ensure-task_work-fix.patch
@@ -0,0 +1,115 @@
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+Date: Tue, 21 May 2024 13:43:48 -0600
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+To: io-uring <io-uring@vger.kernel.org>
+From: Jens Axboe <axboe@kernel.dk>
+Subject: [PATCH v2] io_uring/sqpoll: ensure that normal task_work is also run
+ timely
+Cc: Christian Heusel <christian@heusel.eu>, Andrew Udvare <audvare@gmail.com>
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+
+With the move to private task_work, SQPOLL neglected to also run the
+normal task_work, if any is pending. This will eventually get run, but
+we should run it with the private task_work to ensure that things like
+a final fput() is processed in a timely fashion.
+
+Cc: stable@vger.kernel.org
+Link: https://lore.kernel.org/all/313824bc-799d-414f-96b7-e6de57c7e21d@gmail.com/
+Reported-by: Andrew Udvare <audvare@gmail.com>
+Fixes: af5d68f8892f ("io_uring/sqpoll: manage task_work privately")
+Tested-by: Christian Heusel <christian@heusel.eu>
+Tested-by: Andrew Udvare <audvare@gmail.com>
+Signed-off-by: Jens Axboe <axboe@kernel.dk>
+
+---
+
+V2: move the task_work_run() section so we're always guaranteed it
+    runs after any task_work. Ran the previous test cases again, both
+    the yarn based one and the liburing test case, and they still work
+    as they should. Previously, if we had a retry condition due to being
+    flooded with task_work, then we'd not run the kernel side task_work.
+
+diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c
+index 554c7212aa46..b3722e5275e7 100644
+--- a/io_uring/sqpoll.c
++++ b/io_uring/sqpoll.c
+@@ -238,11 +238,13 @@ static unsigned int io_sq_tw(struct llist_node **retry_list, int max_entries)
+ 	if (*retry_list) {
+ 		*retry_list = io_handle_tw_list(*retry_list, &count, max_entries);
+ 		if (count >= max_entries)
+-			return count;
++			goto out;
+ 		max_entries -= count;
+ 	}
+-
+ 	*retry_list = tctx_task_work_run(tctx, max_entries, &count);
++out:
++	if (task_work_pending(current))
++		task_work_run();
+ 	return count;
+ }
+ 
+-- 
+Jens Axboe