Re: [PATCH 1/2] mm: hugetlb: Return -ENOSPC on memcg charge failure

[Muchun Song <muchun.song@linux.dev>]

> On Sep 2, 2026, at 16:22, Ackerley Tng via B4 Relay <devnull+ackerleytng.google.com@kernel.org> wrote:
> 
> From: Ackerley Tng <ackerleytng@google.com>
> 
> When mem_cgroup_charge_hugetlb() fails with -ENOMEM, alloc_hugetlb_folio()
> currently propagates this error. This results in the page fault handler
> returning VM_FAULT_OOM.
> 
> Because HugeTLB allocations are high-order and use __GFP_RETRY_MAYFAIL,
> they bypass the OOM killer. Returning VM_FAULT_OOM to the #PF handler
> without triggering the OOM killer (or having it make progress) leads to
> an infinite loop of retrying the fault.
> 
> Avoid this loop by returning -ENOSPC when charging fails, which maps to
> VM_FAULT_SIGBUS, terminating the process cleanly.
> 
> Make mem_cgroup_charge_hugetlb() fault handling use a common error handling
> path, the same handling used for hugetlb_cgroup_uncharge_cgroup{,_rsvd}(),
> which also don't trigger the OOM killer and hence opt to terminate the
> process with a SIGBUS.
> 
> Fixes: 991135774c0e0 ("memcg/hugetlb: introduce mem_cgroup_charge_hugetlb")
> Cc: stable@vger.kernel.org
> Signed-off-by: Ackerley Tng <ackerleytng@google.com>

It looks like someone fixed a similar issue before, but I don't remember the
details. Anyway:

Reviewed-by: Muchun Song <muchun.song@linux.dev>

Thanks.