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From:   "Zhang, Tina" <tina.zhang@intel.com>
To:     Jason Gunthorpe <jgg@ziepe.ca>
CC:     "Tian, Kevin" <kevin.tian@intel.com>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Michael Shavit <mshavit@google.com>,
        Vasant Hegde <vasant.hegde@amd.com>,
        Nicolin Chen <nicolinc@nvidia.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "iommu@lists.linux.dev" <iommu@lists.linux.dev>
Subject: RE: [PATCH v7 4/5] iommu: Support mm PASID 1:n with sva domains
Thread-Topic: [PATCH v7 4/5] iommu: Support mm PASID 1:n with sva domains
Thread-Index: AQHZ/Lhw9B1X1cp/m02MO/EHJI2kHLBGKqIAgAFNwjA=
Date:   Fri, 13 Oct 2023 09:57:30 +0000
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References: <20231012030112.82270-1-tina.zhang@intel.com>
 <20231012030112.82270-5-tina.zhang@intel.com>
 <20231012134310.GI55194@ziepe.ca>
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Hi,

> -----Original Message-----
> From: Jason Gunthorpe <jgg@ziepe.ca>
> Sent: Thursday, October 12, 2023 9:43 PM
> To: Zhang, Tina <tina.zhang@intel.com>
> Cc: Tian, Kevin <kevin.tian@intel.com>; Lu Baolu <baolu.lu@linux.intel.co=
m>;
> Michael Shavit <mshavit@google.com>; Vasant Hegde
> <vasant.hegde@amd.com>; Nicolin Chen ^C-cc=3Diommu @ lists . linux . dev
> <nicolinc@nvidia.com>; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v7 4/5] iommu: Support mm PASID 1:n with sva domains
>=20
> On Thu, Oct 12, 2023 at 11:01:11AM +0800, Tina Zhang wrote:
>=20
> > @@ -1188,15 +1193,26 @@ static inline bool
> > tegra_dev_iommu_get_stream_id(struct device *dev, u32 *stream  #ifdef
> > CONFIG_IOMMU_SVA  static inline void mm_pasid_init(struct mm_struct
> > *mm)  {
> > -	mm->pasid =3D IOMMU_PASID_INVALID;
> > +	/*
> > +	 * During dup_mm(), a new mm will be memcpy'd from an old one
> and that makes
> > +	 * the new mm and the old one point to a same iommu_mm
> instance. When either
> > +	 * one of the two mms gets released, the iommu_mm instance is
> freed, leaving
> > +	 * the other mm running into a use-after-free/double-free problem.
> To avoid
> > +	 * the problem, zeroing the iommu_mm pointer of a new mm is
> needed here.
> > +	 */
> > +	mm->iommu_mm =3D NULL;
> >  }
>=20
> newlines after all the }, between functions doesn't checkpatch complain?
Checked with checkpatch but didn't see any complaining.

>=20
> IMHO this hunk should be moved to the prior patch.
In this patch, we switch to use mm->iommu_mm. That's why the iommu_mm initi=
alization is put in this patch.

I think I met some problem about my mailbox when I was sending this new ver=
sion. It didn't cc iommu@lists.linux.dev. Should I resend this version agai=
n or reply to the patches with iommu@lists.linux.dev cc'd?

Regards,
-Tina
>=20
> But it all looks good to me now
>=20
> Thanks,
> Jason