From: Jason Gunthorpe <jgg@nvidia.com>
To: Peizhe Liu <peizheliu@utexas.edu>
Cc: Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Lu Baolu <baolu.lu@linux.intel.com>,
Kevin Tian <kevin.tian@intel.com>,
Jean-Philippe Brucker <jpb@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Shakeel Butt <shakeel.butt@linux.dev>,
Muchun Song <muchun.song@linux.dev>,
iommu@lists.linux.dev, linux-mm@kvack.org,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] iommu/sva: Charge IOPF allocations to the faulting mm's memcg
Date: Tue, 13 Oct 2026 09:22:41 -0300 [thread overview]
Message-ID: <20261013122241.GR13920@nvidia.com> (raw)
In-Reply-To: <20261012200823.699316-1-peizheliu@utexas.edu>
On Mon, Oct 12, 2026 at 03:08:23PM -0500, Peizhe Liu wrote:
> iommu_sva_handle_mm() runs from the IOPF workqueue and calls
> handle_mm_fault() for the faulting mm, but does not set the active
> memcg. File-backed faults can allocate page cache through
> mem_cgroup_charge(folio, NULL, gfp), which falls back to the root memcg
> when the worker has neither an active memcg nor a current->mm. Page
> cache faulted in by a device is therefore charged to root and escapes
> the task's memory.max.
>
> Set the active memcg to the one associated with the faulting mm while
> handling the fault, and restore the previous value afterwards.
>
> Fixes: fc36479db74e ("iommu: Add a page fault handler")
> Signed-off-by: Peizhe Liu <peizheliu@utexas.edu>
> ---
> Tested on a Xeon Gold 5512U with Intel DSA, based on iommu/next.
> Before/after testing confirmed that the block-on-fault case charges
> the page cache to the task's memcg after this change and is subject
> to memory.max.
>
> drivers/iommu/iommu-sva.c | 6 ++++++
> 1 file changed, 6 insertions(+)
It makes sense to me
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Jason
prev parent reply other threads:[~2026-10-13 12:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-12 20:08 [PATCH] iommu/sva: Charge IOPF allocations to the faulting mm's memcg Peizhe Liu
2026-10-12 23:07 ` Shakeel Butt
2026-10-13 2:23 ` Muchun Song
2026-10-13 12:22 ` Jason Gunthorpe [this message]
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