diff options
| author | Jens Axboe <axboe@kernel.dk> | 2026-03-09 14:21:37 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-03-19 16:08:51 +0100 |
| commit | 7cc4530b3e952d4a5947e1e55d06620d8845d4f5 (patch) | |
| tree | b74a68cef518fc493601b91625d836bf47ccd1cb /include | |
| parent | ae3831b44f477de048287493e184fc3ff913b624 (diff) | |
io_uring: ensure ctx->rings is stable for task work flags manipulation
Commit 96189080265e6bb5dde3a4afbaf947af493e3f82 upstream.
If DEFER_TASKRUN | SETUP_TASKRUN is used and task work is added while
the ring is being resized, it's possible for the OR'ing of
IORING_SQ_TASKRUN to happen in the small window of swapping into the
new rings and the old rings being freed.
Prevent this by adding a 2nd ->rings pointer, ->rings_rcu, which is
protected by RCU. The task work flags manipulation is inside RCU
already, and if the resize ring freeing is done post an RCU synchronize,
then there's no need to add locking to the fast path of task work
additions.
Note: this is only done for DEFER_TASKRUN, as that's the only setup mode
that supports ring resizing. If this ever changes, then they too need to
use the io_ctx_mark_taskrun() helper.
Link: https://lore.kernel.org/io-uring/20260309062759.482210-1-naup96721@gmail.com/
Cc: stable@vger.kernel.org
Fixes: 79cfe9e59c2a ("io_uring/register: add IORING_REGISTER_RESIZE_RINGS")
Reported-by: Hao-Yu Yang <naup96721@gmail.com>
Suggested-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/io_uring_types.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h index b4d8aca3e786..3f3506056b9a 100644 --- a/include/linux/io_uring_types.h +++ b/include/linux/io_uring_types.h @@ -372,6 +372,7 @@ struct io_ring_ctx { * regularly bounce b/w CPUs. */ struct { + struct io_rings __rcu *rings_rcu; struct llist_head work_llist; struct llist_head retry_llist; unsigned long check_cq; |