On 1/24/25 20:47, Jens Axboe wrote:
On 1/24/25 11:53 AM, Pavel Begunkov wrote:[ upstream commit 3181e22fb79910c7071e84a43af93ac89e8a7106 ] There are reports of mariadb hangs, which is caused by a missing barrier in the waking code resulting in waiters losing events. The problem was introduced in a backport 3ab9326f93ec4 ("io_uring: wake up optimisations"), and the change restores the barrier present in the original commit 3ab9326f93ec4 ("io_uring: wake up optimisations") Reported by: Xan Charbonnet <xan@xxxxxxxxxxxxxx> Fixes: 3ab9326f93ec4 ("io_uring: wake up optimisations") Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1093243#99 Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx> --- io_uring/io_uring.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 9b58ba4616d40..e5a8ee944ef59 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -592,8 +592,10 @@ static inline void __io_cq_unlock_post_flush(struct io_ring_ctx *ctx) io_commit_cqring(ctx); spin_unlock(&ctx->completion_lock); io_commit_cqring_flush(ctx); - if (!(ctx->flags & IORING_SETUP_DEFER_TASKRUN)) + if (!(ctx->flags & IORING_SETUP_DEFER_TASKRUN)) { + smp_mb(); __io_cqring_wake(ctx); + } }We could probably just s/__io_cqring_wake/io_cqring_wake here to get the same effect. Not that it really matters, it's just simpler.
Right, I noticed but am keeping it closer to the original in case we'd need to port more in the future. -- Pavel Begunkov
