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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi, On 28. 10. 26, 18:00, Greg Kroah-Hartman wrote: > 7.3-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Juanlu Herrero > > commit 937d38dcacd675dc0572d6c9b6743960df3128ed upstream. Our machinery flags this is needed as a fix: 67bb1ad9a517 ("io_uring/poll: don't loop on HUP with multiple references") > If a wakeup sets IO_POLL_RETRY_FLAG between the owning task consuming > the existing instance of IO_POLL_RETRY_FLAG and the loop check > of io_poll_check_events(), then we stall on processing the request > until an unrelated wakeup comes along. > > Using atomic_cmpxchg instead of atomic_sub_return to guarantee both the > count v and poll_refs are 0 and no wake-ups are missed. > > Cc: stable@vger.kernel.org > Fixes: a26a35e9019f ("io_uring: make poll refs more robust") > Signed-off-by: Juanlu Herrero > Assisted-by: LLM > Suggested-by: Anand Natarajan > Link: https://patch.msgid.link/20261013-pu-cmpxchg-v1-1-4ddc10fd8a03@fastmail.com > Signed-off-by: Jens Axboe > Signed-off-by: Greg Kroah-Hartman > --- > io_uring/poll.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > --- a/io_uring/poll.c > +++ b/io_uring/poll.c > @@ -330,7 +330,8 @@ static int io_poll_check_events(struct i > * Release all references, retry if someone tried to restart > * task_work while we were executing it. > */ > - } while (atomic_sub_return(v, &req->poll_refs) & IO_POLL_REF_MASK); > + v &= IO_POLL_REF_MASK; > + } while (atomic_cmpxchg(&req->poll_refs, v, 0) != v); > > io_napi_add(req); > return IOU_POLL_NO_ACTION; thanks, -- js suse labs