Re: [PATCH 2/7] dma-buf/udmabuf: account the page array metadata to memcg

[sashiko-bot@kernel.org]

> From: Tao Cui <cuitao@kylinos.cn>
> 
> udmabuf pins the pages of a memfd and hands them out as a dma-buf.  The
> data pages keep the accounting of the memfd they were instantiated in,
> but the bookkeeping around them does not: the page pointer array and
> the pinned_folios array, both sized by the buffer page count, plus the
> transient folios array sized by the memfd folio count, are plain
> GFP_KERNEL.  A 1GB buffer costs about 4MB of uncharged SUnreclaim
> memory, and size_limit_mb defaults to INT_MAX.
> 
> Charge the three kvmalloc allocations so the creator pays for the
> metadata it induces.  The system heap in the same subsystem already
> accounts its buffer allocation; the data pages here stay with the
> memfd.
> 
> 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=2