Re: [PATCH v2 2/4] cxl/memdev: Hold memdev lock during memdev poison injection/clear

[Li Ming]

在 2026/4/21 23:29, Dave Jiang 写道:
> On 4/21/26 3:48 AM, Li Ming wrote:
> > 在 2026/4/12 03:23, Dan Williams 写道:
> > > Dave Jiang wrote:
> > > > On 3/18/26 4:59 AM, Li Ming wrote:
> > > > > 在 2026/3/17 23:00, Dave Jiang 写道:
> > > > > > On 3/14/26 12:06 AM, Li Ming wrote:
> > > > > > > CXL memdev poison injection/clearing debugfs interfaces are visible
> > > > > > > before the CXL memdev endpoint initialization, If user accesses the
> > > > > > > interfaces before cxlmd->endpoint updated, it is possible to access an
> > > > > > > invalid endpoint in cxl_dpa_to_region().
> > > > > > >
> > > > > > > Hold CXL memdev lock at the beginning of the interfaces, this blocks the
> > > > > > > interfaces until CXL memdev probing completed.
> > > > > > >
> > > > > > > The following patch will check the given endpoint validity in
> > > > > > > cxl_dpa_to_region().
> > > > > > >
> > > > > > > Suggested-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> > > > > > > Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx>
> > > > > > > Reviewed-by: Alison Schofield <alison.schofield@xxxxxxxxx>
> > > > > > > Signed-off-by: Li Ming <ming.li@xxxxxxxxxxxx>
> > > > > > Hi Ming, I dropped this patch with Dan's comments [1] and updated cxl/next. Please check and make sure everything looks ok to you. Thanks!
> > > > > >
> > > > > > [1]: https://lore.kernel.org/linux-cxl/69b8b81621e16_452b100e@dwillia2-mobl4.notmuch/
> > > > > Hi Dave,
> > > > >
> > > > > I think there is no change needed in this patch, just need a independent patch for holding memdev lock in cxl_region_debugfs_poison_inject/clear.
> > > > >
> > > > > Or you want to review this patch again?
> > > > No. Maybe I misunderstood the comment from Dan. So we should keep this patch?
> > > tl;dr: yes, this patch is *now* valid.
> > >
> > > As originally structured having patch2 before patch3 added no value.
> > > Going forward I would say do not structure a series such that a new lock
> > > taken in patch N starts being useful in patch N+1.
> > >
> > > I assume that is what:
> > >
> > > "The following patch will check the given endpoint validity in
> > > cxl_dpa_to_region()."
> > >
> > > ...is trying to say, but when commits are applied to the tree it is
> > > difficult to see that this commit was from a series.
> > >
> > > So do pick this one up, but the changelog needs adjusting. Something
> > > like:
> > >
> > > "cxl_dpa_to_region() assumes that it is running a context where it is not
> > > racing changes to "cxlmd->dev.driver". Acquire the memdev device lock in
> > > the debugfs entry points to preclude debugfs usage racing cxl_mem driver
> > > detach."
> > >
> > > With that you can add:
> > >
> > > Reviewed-by: Dan Williams <djbw@xxxxxxxxxx>
> > Hi Dave,
> >
> > Will you pick this patch with changes from Dan's comment? Or I need to send out a new version?
> I believe it's merged into linus/master already. Can you check and see if everything looks correct?

I don't see this patch in linus/master or cxl/next. I remember you 
dropped it after applying the patchset to cxl/next.


Ming