From 4d327bbd1cd2485783553b6b2b401aa475f90dd0 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 30 Jul 2026 06:50:47 -0600 Subject: [PATCH] io_uring/futex: only mark private futex waits as inflight Inflight tracking of futex wait requests exists to ensure that do_exit() -> io_uring_files_cancel() cancels them before the mm goes away, as a private futex wait depends on the mm private futex hash staying alive for the duration of the request. Shared futexes have no such dependency. A FLAGS_SHARED request always resolves to either an inode based key or an mm-shared key, both of which fail futex_key_is_private() and hence always hash into the global futex hash, whose lifetime isn't tied to the mm. Only mark vectored futex waits as inflight if the futex is private. Cc: stable@vger.kernel.org Fixes: 079afb081c42 ("io_uring/futex: mark wait requests as inflight") Link: https://lore.kernel.org/io-uring/CANGjgdn=R_qyUdE=j9za+vkmqcxacbP-84OHXF4nZ4ho9qRyVg@mail.gmail.com/ Signed-off-by: Jens Axboe --- io_uring/futex.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/io_uring/futex.c b/io_uring/futex.c index eea0425f2bcb..f0d80a444f45 100644 --- a/io_uring/futex.c +++ b/io_uring/futex.c @@ -154,14 +154,16 @@ int io_futex_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) int io_futex_wait_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) { + struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); int ret; ret = io_futex_prep(req, sqe); if (unlikely(ret)) return ret; - /* Mark as inflight, so file exit cancelation will find it */ - io_req_track_inflight(req); + /* inflight tracking only needed for mm private hash */ + if (!(iof->futex_flags & FLAGS_SHARED)) + io_req_track_inflight(req); return 0; } @@ -186,6 +188,7 @@ int io_futexv_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) { struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); struct io_futexv_data *ifd; + unsigned int i; int ret; /* No flags or mask supported for waitv */ @@ -210,8 +213,14 @@ int io_futexv_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) return ret; } - /* Mark as inflight, so file exit cancelation will find it */ - io_req_track_inflight(req); + /* inflight tracking only needed for mm private hash */ + for (i = 0; i < iof->futex_nr; i++) { + if (!(ifd->futexv[i].w.flags & FLAGS_SHARED)) { + io_req_track_inflight(req); + break; + } + } + iof->futexv_unqueued = 0; req->flags |= REQ_F_ASYNC_DATA; req->async_data = ifd;