[PATCH] io_uring: return back safer resurrect

[PATCH] io_uring: return back safer resurrect

[Lee Jones]

Stable Team,

> Revert of revert of "io_uring: wait potential ->release() on resurrect",
> which adds a helper for resurrect not racing completion reinit, as was
> removed because of a strange bug with no clear root or link to the
> patch.
> 
> Was improved, instead of rcu_synchronize(), just wait_for_completion()
> because we're at 0 refs and it will happen very shortly. Specifically
> use non-interruptible version to ignore all pending signals that may
> have ended prior interruptible wait.
> 
> This reverts commit cb5e1b81304e089ee3ca948db4d29f71902eb575.
> 
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> ---
>  fs/io_uring.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)

Please back-port this as far as it will apply.

Definitely through v5.10.y.

It solves a critical bug.

Subject: "io_uring: return back safer resurrect"

Upstream commit:: f70865db5ff35f5ed0c7e9ef63e7cca3d4947f04

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [PATCH] io_uring: return back safer resurrect

[Greg KH]

On Wed, Mar 16, 2022 at 04:18:16PM +0000, Lee Jones wrote:
> Stable Team,
> 
> > Revert of revert of "io_uring: wait potential ->release() on resurrect",
> > which adds a helper for resurrect not racing completion reinit, as was
> > removed because of a strange bug with no clear root or link to the
> > patch.
> > 
> > Was improved, instead of rcu_synchronize(), just wait_for_completion()
> > because we're at 0 refs and it will happen very shortly. Specifically
> > use non-interruptible version to ignore all pending signals that may
> > have ended prior interruptible wait.
> > 
> > This reverts commit cb5e1b81304e089ee3ca948db4d29f71902eb575.
> > 
> > Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> > ---
> >  fs/io_uring.c | 18 ++++++++++++++----
> >  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> Please back-port this as far as it will apply.
> 
> Definitely through v5.10.y.
> 
> It solves a critical bug.
> 
> Subject: "io_uring: return back safer resurrect"
> 
> Upstream commit:: f70865db5ff35f5ed0c7e9ef63e7cca3d4947f04

It only applies to 5.10.y.  It showed up in 5.12, so if you want it
further back than 5.10.y, can you provide a working backport?

thanks,

greg k-h

Re: [PATCH] io_uring: return back safer resurrect

[Lee Jones]

On Wed, 16 Mar 2022, Greg KH wrote:

> On Wed, Mar 16, 2022 at 04:18:16PM +0000, Lee Jones wrote:
> > Stable Team,
> > 
> > > Revert of revert of "io_uring: wait potential ->release() on resurrect",
> > > which adds a helper for resurrect not racing completion reinit, as was
> > > removed because of a strange bug with no clear root or link to the
> > > patch.
> > > 
> > > Was improved, instead of rcu_synchronize(), just wait_for_completion()
> > > because we're at 0 refs and it will happen very shortly. Specifically
> > > use non-interruptible version to ignore all pending signals that may
> > > have ended prior interruptible wait.
> > > 
> > > This reverts commit cb5e1b81304e089ee3ca948db4d29f71902eb575.
> > > 
> > > Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> > > ---
> > >  fs/io_uring.c | 18 ++++++++++++++----
> > >  1 file changed, 14 insertions(+), 4 deletions(-)
> > 
> > Please back-port this as far as it will apply.
> > 
> > Definitely through v5.10.y.
> > 
> > It solves a critical bug.
> > 
> > Subject: "io_uring: return back safer resurrect"
> > 
> > Upstream commit:: f70865db5ff35f5ed0c7e9ef63e7cca3d4947f04
> 
> It only applies to 5.10.y.  It showed up in 5.12, so if you want it
> further back than 5.10.y, can you provide a working backport?

Works for me, thanks.

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog