linux-kernel - [PATCH 1/2] Revert "udmabuf: fix vmap

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Message-ID: <20250415031548.2007942-2-link@vivo.com>
Date: Tue, 15 Apr 2025 11:15:46 +0800
From: Huan Yang <link@...o.com>
To: Sumit Semwal <sumit.semwal@...aro.org>,
	Christian König <christian.koenig@....com>,
	Gerd Hoffmann <kraxel@...hat.com>,
	Vivek Kasireddy <vivek.kasireddy@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Airlie <airlied@...hat.com>,
	linux-media@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	linaro-mm-sig@...ts.linaro.org,
	linux-kernel@...r.kernel.org
Cc: opensource.kernel@...o.com,
	Huan Yang <link@...o.com>,
	Bingbu Cao <bingbu.cao@...ux.intel.com>
Subject: [PATCH 1/2] Revert "udmabuf: fix vmap_udmabuf error page set"

This reverts commit 18d7de823b7150344d242c3677e65d68c5271b04.

This given a misuse of vmap_pfn, vmap_pfn only allow none-page based
user invoke, i.e. PCIe BARs and other.

Signed-off-by: Huan Yang <link@...o.com>
Reported-by: Bingbu Cao <bingbu.cao@...ux.intel.com>
Closes: https://lore.kernel.org/dri-devel/eb7e0137-3508-4287-98c4-816c5fd98e10@vivo.com/T/#mbda4f64a3532b32e061f4e8763bc8e307bea3ca8
---
 drivers/dma-buf/Kconfig   |  1 -
 drivers/dma-buf/udmabuf.c | 22 +++++++---------------
 2 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig
index fee04fdb0822..b46eb8a552d7 100644
--- a/drivers/dma-buf/Kconfig
+++ b/drivers/dma-buf/Kconfig
@@ -36,7 +36,6 @@ config UDMABUF
 	depends on DMA_SHARED_BUFFER
 	depends on MEMFD_CREATE || COMPILE_TEST
 	depends on MMU
-	select VMAP_PFN
 	help
 	  A driver to let userspace turn memfd regions into dma-bufs.
 	  Qemu can use this to create host dmabufs for guest framebuffers.
diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index 7eee3eb47a8e..79845565089d 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -109,29 +109,21 @@ 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;
-	unsigned long *pfns;
+	struct page **pages;
 	void *vaddr;
 	pgoff_t pg;
 
 	dma_resv_assert_held(buf->resv);
 
-	/**
-	 * 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)
+	pages = kvmalloc_array(ubuf->pagecount, sizeof(*pages), GFP_KERNEL);
+	if (!pages)
 		return -ENOMEM;
 
-	for (pg = 0; pg < ubuf->pagecount; pg++) {
-		unsigned long pfn = folio_pfn(ubuf->folios[pg]);
-
-		pfn += ubuf->offsets[pg] >> PAGE_SHIFT;
-		pfns[pg] = pfn;
-	}
+	for (pg = 0; pg < ubuf->pagecount; pg++)
+		pages[pg] = &ubuf->folios[pg]->page;
 
-	vaddr = vmap_pfn(pfns, ubuf->pagecount, PAGE_KERNEL);
-	kvfree(pfns);
+	vaddr = vm_map_ram(pages, ubuf->pagecount, -1);
+	kvfree(pages);
 	if (!vaddr)
 		return -EINVAL;
 
-- 
2.48.1