This is a note to let you know that I've just added the patch titled
io_uring: unconditionally grab req->task
to the 5.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
io_uring-unconditionally-grab-req-task.patch
and it can be found in the queue-5.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Oct 29 01:16:54 PM CET 2020
From: Jens Axboe <axboe@xxxxxxxxx>
Date: Mon, 12 Oct 2020 11:25:39 -0600
Subject: io_uring: unconditionally grab req->task
From: Jens Axboe <axboe@xxxxxxxxx>
commit e3bc8e9dad7f2f83cc807111d4472164c9210153 upstream.
Sometimes we assign a weak reference to it, sometimes we grab a
reference to it. Clean this up and make it unconditional, and drop the
flag related to tracking this state.
Reviewed-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/io_uring.c | 26 +++-----------------------
1 file changed, 3 insertions(+), 23 deletions(-)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -550,7 +550,6 @@ enum {
REQ_F_NO_FILE_TABLE_BIT,
REQ_F_QUEUE_TIMEOUT_BIT,
REQ_F_WORK_INITIALIZED_BIT,
- REQ_F_TASK_PINNED_BIT,
/* not a real bit, just to check we're not overflowing the space */
__REQ_F_LAST_BIT,
@@ -608,8 +607,6 @@ enum {
REQ_F_QUEUE_TIMEOUT = BIT(REQ_F_QUEUE_TIMEOUT_BIT),
/* io_wq_work is initialized */
REQ_F_WORK_INITIALIZED = BIT(REQ_F_WORK_INITIALIZED_BIT),
- /* req->task is refcounted */
- REQ_F_TASK_PINNED = BIT(REQ_F_TASK_PINNED_BIT),
};
struct async_poll {
@@ -924,21 +921,6 @@ struct sock *io_uring_get_socket(struct
}
EXPORT_SYMBOL(io_uring_get_socket);
-static void io_get_req_task(struct io_kiocb *req)
-{
- if (req->flags & REQ_F_TASK_PINNED)
- return;
- get_task_struct(req->task);
- req->flags |= REQ_F_TASK_PINNED;
-}
-
-/* not idempotent -- it doesn't clear REQ_F_TASK_PINNED */
-static void __io_put_req_task(struct io_kiocb *req)
-{
- if (req->flags & REQ_F_TASK_PINNED)
- put_task_struct(req->task);
-}
-
static void io_file_put_work(struct work_struct *work);
/*
@@ -1455,7 +1437,7 @@ static void __io_req_aux_free(struct io_
kfree(req->io);
if (req->file)
io_put_file(req, req->file, (req->flags & REQ_F_FIXED_FILE));
- __io_put_req_task(req);
+ put_task_struct(req->task);
io_req_work_drop_env(req);
}
@@ -1765,7 +1747,7 @@ static inline bool io_req_multi_free(str
if ((req->flags & REQ_F_LINK_HEAD) || io_is_fallback_req(req))
return false;
- if (req->file || req->io)
+ if (req->file || req->io || req->task)
rb->need_iter++;
rb->reqs[rb->to_free++] = req;
@@ -4584,7 +4566,6 @@ static bool io_arm_poll_handler(struct i
if (req->flags & REQ_F_WORK_INITIALIZED)
memcpy(&apoll->work, &req->work, sizeof(req->work));
- io_get_req_task(req);
req->apoll = apoll;
INIT_HLIST_NODE(&req->hash_node);
@@ -4774,8 +4755,6 @@ static int io_poll_add_prep(struct io_ki
events = READ_ONCE(sqe->poll_events);
poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP;
-
- io_get_req_task(req);
return 0;
}
@@ -6057,6 +6036,7 @@ static int io_init_req(struct io_ring_ct
/* one is dropped after submission, the other at completion */
refcount_set(&req->refs, 2);
req->task = current;
+ get_task_struct(req->task);
req->result = 0;
if (unlikely(req->opcode >= IORING_OP_LAST))
Patches currently in stable-queue which might be from axboe@xxxxxxxxx are
queue-5.8/io_uring-convert-advanced-xarray-uses-to-the-normal-api.patch
queue-5.8/io_uring-don-t-run-task-work-on-an-exiting-task.patch
queue-5.8/io_uring-reference-nsproxy-for-file-table-commands.patch
queue-5.8/io_uring-stash-ctx-task-reference-for-sqpoll.patch
queue-5.8/io_uring-return-cancelation-status-from-poll-timeout-files-handlers.patch
queue-5.8/io_uring-fix-xarray-usage-in-io_uring_add_task_file.patch
queue-5.8/io_uring-fix-use-of-xarray-in-__io_uring_files_cancel.patch
queue-5.8/io-wq-fix-use-after-free-in-io_wq_worker_running.patch
queue-5.8/io_uring-don-t-rely-on-weak-files-references.patch
queue-5.8/io_uring-allow-timeout-poll-files-killing-to-take-task-into-account.patch
queue-5.8/io_uring-move-dropping-of-files-into-separate-helper.patch
queue-5.8/io_uring-unconditionally-grab-req-task.patch
queue-5.8/io_uring-enable-task-files-specific-overflow-flushing.patch
queue-5.8/io_wq-make-io_wqe-lock-a-raw_spinlock_t.patch
queue-5.8/io_uring-no-need-to-call-xa_destroy-on-empty-xarray.patch
