Re: [PATCH] dax/device: defer publishing the dynamic pgmap

[Andrew Morton]

On Tue, 29 Sep 2026 14:45:15 -0700 Alison Schofield <alison.schofield@xxxxxxxxx> wrote:

> On Sun, Sep 27, 2026 at 01:05:26PM -0700, Andrew Morton wrote:
> > On Sun, 27 Sep 2026 19:47:36 +0800 Jiale Yao <yaojiale02@xxxxxxx> wrote:
> > 
> > > The dynamic device-dax probe path publishes its devm-allocated pgmap
> > > before several operations that can still fail.  If one of them fails,
> > > devres frees the pgmap while dev_dax->pgmap remains non-NULL.  A later
> > > bind then fails the dynamic-dax invariant check and leaves the device
> > > unusable until its region is recreated.
> > > 
> > > Defer assigning dev_dax->pgmap until the final devm action has been
> > > installed and probe can no longer fail.  A failed probe then never
> > > publishes the temporary pgmap.
> > 
> > lgtm, thanks.
> > 
> > > Fixes: fc65c4eb0b2a ("device-dax: ensure dev_dax->pgmap is valid for dynamic devices")
> > > Cc: stable@xxxxxxxxxxxxxxx
> > > Signed-off-by: Jiale Yao <yaojiale02@xxxxxxx>
> > 
> > I'll queue this for next-merge-window as it doesn't seem very urgent. 
> > Retaining cc:stable.  I've marked it as "needs maintainer acks".
> 
> Hi Andrew,
> 
> I'm wondering why you are picking this one up?  I have taken
> on the role of drivers/dax patch wrangling recently (past 2 releases)
> and was thinking this fits within that group. Not that I don't like
> the help, just wondering if I've misunderstood who does what where.

Oh, OK.  Muscle memory?  I've handled quite a lot of drivers/dax
patches in the past, including the one which is being fixed here.  The
subsystem has never felt more than somewhat on-topic.

I'll remove this one from mm.git.