| Message ID | 20241031163257.3616106-1-maharmstone@fb.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [1/2] io_uring/cmd: let cmds to know about dying task | expand |
On Fri, Nov 1, 2024 at 12:33 AM Mark Harmstone <maharmstone@fb.com> wrote: > > From: Pavel Begunkov <asml.silence@gmail.com> > > When the taks that submitted a request is dying, a task work for that > request might get run by a kernel thread or even worse by a half > dismantled task. We can't just cancel the task work without running the > callback as the cmd might need to do some clean up, so pass a flag > instead. If set, it's not safe to access any task resources and the > callback is expected to cancel the cmd ASAP. > > Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> > --- > include/linux/io_uring_types.h | 1 + > io_uring/uring_cmd.c | 6 +++++- > 2 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h > index 4b9ba523978d..2ee5dc105b58 100644 > --- a/include/linux/io_uring_types.h > +++ b/include/linux/io_uring_types.h > @@ -37,6 +37,7 @@ enum io_uring_cmd_flags { > /* set when uring wants to cancel a previously issued command */ > IO_URING_F_CANCEL = (1 << 11), > IO_URING_F_COMPAT = (1 << 12), > + IO_URING_F_TASK_DEAD = (1 << 13), > }; > > struct io_wq_work_node { > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > index 39c3c816ec78..78a8ba5d39ae 100644 > --- a/io_uring/uring_cmd.c > +++ b/io_uring/uring_cmd.c > @@ -119,9 +119,13 @@ EXPORT_SYMBOL_GPL(io_uring_cmd_mark_cancelable); > static void io_uring_cmd_work(struct io_kiocb *req, struct io_tw_state *ts) > { > struct io_uring_cmd *ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd); > + unsigned int flags = IO_URING_F_COMPLETE_DEFER; > + > + if (req->task != current) > + flags |= IO_URING_F_TASK_DEAD; Looks fine, Reviewed-by: Ming Lei <ming.lei@redhat.com> BTW, uring_cmd can get notified when the ring/task is dying if io_uring_cmd_mark_cancelable() is called on the command. Thanks, Ming
On 10/31/24 16:32, Mark Harmstone wrote: > From: Pavel Begunkov <asml.silence@gmail.com> > > When the taks that submitted a request is dying, a task work for that > request might get run by a kernel thread or even worse by a half > dismantled task. We can't just cancel the task work without running the > callback as the cmd might need to do some clean up, so pass a flag > instead. If set, it's not safe to access any task resources and the > callback is expected to cancel the cmd ASAP. I was just going to write that you didn't CC io_uring for the rest of the series, but I can't find it in the btrfs list, did did something go wrong? Regardless, I think it should be fine to merge it through the btrfs tree
On 10/31/24 16:32, Mark Harmstone wrote: ... > struct io_wq_work_node { > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > index 39c3c816ec78..78a8ba5d39ae 100644 > --- a/io_uring/uring_cmd.c > +++ b/io_uring/uring_cmd.c > @@ -119,9 +119,13 @@ EXPORT_SYMBOL_GPL(io_uring_cmd_mark_cancelable); > static void io_uring_cmd_work(struct io_kiocb *req, struct io_tw_state *ts) > { > struct io_uring_cmd *ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd); > + unsigned int flags = IO_URING_F_COMPLETE_DEFER; > + > + if (req->task != current) > + flags |= IO_URING_F_TASK_DEAD; Actually, the patch is broken. I have no clue why Bernd changed it and left my name, here was the original: https://lore.kernel.org/io-uring/d2528a1c-3d7c-4124-953c-02e8e415529e@gmail.com/ also now it'll also conflict with patches Jens is queuing, I'll send a replacement btrfs can take.
diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h index 4b9ba523978d..2ee5dc105b58 100644 --- a/include/linux/io_uring_types.h +++ b/include/linux/io_uring_types.h @@ -37,6 +37,7 @@ enum io_uring_cmd_flags { /* set when uring wants to cancel a previously issued command */ IO_URING_F_CANCEL = (1 << 11), IO_URING_F_COMPAT = (1 << 12), + IO_URING_F_TASK_DEAD = (1 << 13), }; struct io_wq_work_node { diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c index 39c3c816ec78..78a8ba5d39ae 100644 --- a/io_uring/uring_cmd.c +++ b/io_uring/uring_cmd.c @@ -119,9 +119,13 @@ EXPORT_SYMBOL_GPL(io_uring_cmd_mark_cancelable); static void io_uring_cmd_work(struct io_kiocb *req, struct io_tw_state *ts) { struct io_uring_cmd *ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd); + unsigned int flags = IO_URING_F_COMPLETE_DEFER; + + if (req->task != current) + flags |= IO_URING_F_TASK_DEAD; /* task_work executor checks the deffered list completion */ - ioucmd->task_work_cb(ioucmd, IO_URING_F_COMPLETE_DEFER); + ioucmd->task_work_cb(ioucmd, flags); } void __io_uring_cmd_do_in_task(struct io_uring_cmd *ioucmd,