On 11/6/26 14:18, Tao Cui wrote:
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.
T.J. needs to take a look here, but I fear that this might break uAPI.
A lot of the DMA-buf resources are intentionally not charged against memcg.
Regards, Christian.
Signed-off-by: Tao Cui cuitao@kylinos.cn
drivers/dma-buf/udmabuf.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c index df6dd0046242..40182c82df6b 100644 --- a/drivers/dma-buf/udmabuf.c +++ b/drivers/dma-buf/udmabuf.c @@ -190,11 +190,12 @@ static void unpin_all_folios(struct udmabuf *ubuf)
static __always_inline int init_udmabuf(struct udmabuf *ubuf, pgoff_t pgcnt) {
ubuf->pages = kvmalloc_objs(*ubuf->pages, pgcnt);
ubuf->pages = kvmalloc_objs(*ubuf->pages, pgcnt, GFP_KERNEL_ACCOUNT); if (!ubuf->pages) return -ENOMEM;
ubuf->pinned_folios = kvmalloc_objs(*ubuf->pinned_folios, pgcnt);
ubuf->pinned_folios = kvmalloc_objs(*ubuf->pinned_folios, pgcnt,GFP_KERNEL_ACCOUNT); if (!ubuf->pinned_folios) return -ENOMEM;@@ -387,7 +388,7 @@ static long udmabuf_create(struct miscdevice *device, if (ret) goto err;
folios = kvmalloc_objs(*folios, max_nr_folios);
folios = kvmalloc_objs(*folios, max_nr_folios, GFP_KERNEL_ACCOUNT); if (!folios) { ret = -ENOMEM; goto err;-- 2.43.0