在 2024/8/17 8:54, Kasireddy, Vivek 写道:
Hi Huan,
Subject: [PATCH v3 3/5] fix vmap_udmabuf error page set
Please prepend a "udmabuf:" to the subject line and improve the wording.
OK, sorry for this mistake.
Currently vmap_udmabuf set page's array by each folio.
But, ubuf->folios is only contain's the folio's head page.
That mean we repeatedly mapped the folio head page to the vmalloc area.
Due to udmabuf can use hugetlb, if HVO enabled, tail page may not exist,
so, we can't use page array to map, instead, use pfn array.
Signed-off-by: Huan Yang <link@xxxxxxxx>
Suggested-by: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>
---
drivers/dma-buf/udmabuf.c | 22 +++++++++++++++-------
1 file changed, 15 insertions(+), 7 deletions(-)
diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index 3ec72d47bb1c..4ec54c60d76c 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -67,21 +67,29 @@ static int mmap_udmabuf(struct dma_buf *buf,
struct vm_area_struct *vma)
static int vmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
{
struct udmabuf *ubuf = buf->priv;
- struct page **pages;
+ unsigned long *pfns;
I wish there was a way to easily test the vmap scenario but its great that
It need a driver set in kernel. maybe write a debug code in udmabuf?(not
sure)
you are able to eliminate the usage of "struct page" completely from
udmabuf driver, with this patch.
void *vaddr;
pgoff_t pg;
dma_resv_assert_held(buf->resv);
- pages = kvmalloc_array(ubuf->pagecount, sizeof(*pages),
GFP_KERNEL);
- if (!pages)
+ /**
+ * HVO may free tail pages, so just use pfn to map each folio
+ * into vmalloc area.
+ */
+ pfns = kvmalloc_array(ubuf->pagecount, sizeof(*pfns), GFP_KERNEL);
+ if (!pfns)
return -ENOMEM;
- for (pg = 0; pg < ubuf->pagecount; pg++)
- pages[pg] = &ubuf->folios[pg]->page;
+ for (pg = 0; pg < ubuf->pagecount; pg++) {
+ unsigned long pfn = folio_pfn(ubuf->folios[pg]);
- vaddr = vm_map_ram(pages, ubuf->pagecount, -1);
- kvfree(pages);
+ pfn += ubuf->offsets[pg] >> PAGE_SHIFT;
+ pfns[pg] = pfn;
+ }
+
+ vaddr = vmap_pfn(pfns, ubuf->pagecount, PAGE_KERNEL);
Looks like this would require a "select VMAP_PFN" in Kconfig.
Yes, I miss this.
Thank you too much.
Thanks,
Vivek
+ kvfree(pfns);
if (!vaddr)
return -EINVAL;
--
2.45.2
