linux-kernel - RE: [PATCH] dma-remap: Use kvmalloc_array/kvfree for larger dma memory remap

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Message-ID: <a37f80a55eeb4b2eb125e3340320032e@hihonor.com>
Date:   Mon, 15 May 2023 06:59:31 +0000
From:   gaoxu <gaoxu2@...onor.com>
To:     "hch@....de" <hch@....de>,
        "m.szyprowski@...sung.com" <m.szyprowski@...sung.com>
CC:     "robin.murphy@....com" <robin.murphy@....com>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "surenb@...gle.com" <surenb@...gle.com>,
        yipengxiang <yipengxiang@...onor.com>,
        wangbintian 00013160 <bintian.wang@...onor.com>
Subject: RE: [PATCH] dma-remap: Use kvmalloc_array/kvfree for larger dma
 memory remap

Please help to review, thanks.

-----Original Message-----
From: gaoxu 00016977 
Sent: 2023年5月6日 15:34
To: 'hch@....de' <hch@....de>; 'm.szyprowski@...sung.com' <m.szyprowski@...sung.com>
Cc: 'robin.murphy@....com' <robin.murphy@....com>; 'iommu@...ts.linux.dev' <iommu@...ts.linux.dev>; 'linux-kernel@...r.kernel.org' <linux-kernel@...r.kernel.org>; 'surenb@...gle.com' <surenb@...gle.com>; yipengxiang 00013268 <yipengxiang@...onor.com>; wangbintian 00013160 <bintian.wang@...onor.com>; hanfeng 00012985 <feng.han@...onor.com>
Subject: [PATCH] dma-remap: Use kvmalloc_array/kvfree for larger dma memory remap

If dma_direct_alloc() alloc memory in size of 64MB, the inner function
dma_common_contiguous_remap() will allocate 128KB memory by invoking the function kmalloc_array(). and the kmalloc_array seems to fail to try to allocate 128KB mem. work around by doing kvmalloc_array instead.

Signed-off-by: Gao Xu <gaoxu2@...onor.com>
---
 kernel/dma/remap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/dma/remap.c b/kernel/dma/remap.c index b45266680..27596f3b4 100644
--- a/kernel/dma/remap.c
+++ b/kernel/dma/remap.c
@@ -43,13 +43,13 @@ void *dma_common_contiguous_remap(struct page *page, size_t size,
 	void *vaddr;
 	int i;
 
-	pages = kmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
+	pages = kvmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
 	if (!pages)
 		return NULL;
 	for (i = 0; i < count; i++)
 		pages[i] = nth_page(page, i);
 	vaddr = vmap(pages, count, VM_DMA_COHERENT, prot);
-	kfree(pages);
+	kvfree(pages);
 
 	return vaddr;
 }
--
2.17.1