Linux IOMMU Development
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From: Jason Gunthorpe <jgg@nvidia.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Nicolin Chen <nicolinc@nvidia.com>,
	"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
	Lixiao Yang <lixiao.yang@intel.com>,
	Matthew Rosato <mjrosato@linux.ibm.com>,
	"syzbot+1ad12d16afca0e7d2dde@syzkaller.appspotmail.com"
	<syzbot+1ad12d16afca0e7d2dde@syzkaller.appspotmail.com>,
	"syzbot+6c8d756f238a75fc3eb8@syzkaller.appspotmail.com"
	<syzbot+6c8d756f238a75fc3eb8@syzkaller.appspotmail.com>,
	"Liu, Yi L" <yi.l.liu@intel.com>
Subject: Re: [PATCH rc 1/2] iommufd: Do not access the area pointer after unlocking
Date: Tue, 20 Jun 2023 09:36:06 -0300	[thread overview]
Message-ID: <ZJGdNhEd+A0qmA1Z@nvidia.com> (raw)
In-Reply-To: <BN9PR11MB52768CF5BF9526D06C7149DE8C5CA@BN9PR11MB5276.namprd11.prod.outlook.com>

On Tue, Jun 20, 2023 at 05:30:39AM +0000, Tian, Kevin wrote:

> this looks incorrect. If the unmapped range covers more than 1000 areas
> and each area is attached by an access, this logic implies that an error will
> be returned after the first 1000 areas are unmapped.

Yes, that makes sense
 
> IMHO here we want to record the last notified area and compare it in
> retry, e.g.:
> 
> 	struct iopt_area *last_notify_area = NULL;

We can't use the area pointer, but we can keep track of the IOVA and
reset tries as it progresses.

Thanks,
Jason

  reply	other threads:[~2023-06-20 12:36 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-19 18:24 [PATCH rc 0/2] iommufd syzkaller fixes Jason Gunthorpe
2023-06-19 18:24 ` [PATCH rc 1/2] iommufd: Do not access the area pointer after unlocking Jason Gunthorpe
2023-06-20  4:42   ` Nicolin Chen
2023-06-20  5:30     ` Tian, Kevin
2023-06-20 12:36       ` Jason Gunthorpe [this message]
2023-06-19 18:24 ` [PATCH rc 2/2] iommufd: Call iopt_area_contig_done() under the lock Jason Gunthorpe
2023-06-20  5:34   ` Tian, Kevin

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