Re: [PATCH 5/7] iommufd: account the hw_queue page array to memcg

[sashiko-bot@kernel.org]

> From: Tao Cui <cuitao@kylinos.cn>
> 
> IOMMUFD_CMD_HW_QUEUE_ALLOC pins up to max_npages pages just to check
> that a user supplied queue region is physically contiguous, and the
> page array for that check is plain GFP_KERNEL.  The size comes from
> cmd->length, a u64 that is only overflow checked, and the array is
> freed again as soon as the contiguity check fails, so the allocation
> can be repeated concurrently: a 1GB region costs about 2MB of
> uncharged memory per attempt.
> 
> Every other iommufd allocation that scales with user input is already
> charged, and the pinned pages charge the mapper at map time.  Charge
> this array like the rest.
> 
> Signed-off-by: Tao Cui <cuitao@kylinos.cn>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261106131829.3228926-1-cui.tao@linux.dev?part=5