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Message-ID: <868bc7ec-762e-4932-b004-e82df915fa97@vivo.com>
Date: Mon, 12 Aug 2024 10:49:42 +0800
From: Huan Yang <link@...o.com>
To: "Kasireddy, Vivek" <vivek.kasireddy@...el.com>,
Gerd Hoffmann <kraxel@...hat.com>, Sumit Semwal <sumit.semwal@...aro.org>,
Christian König <christian.koenig@....com>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
"linaro-mm-sig@...ts.linaro.org" <linaro-mm-sig@...ts.linaro.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc: "opensource.kernel@...o.com" <opensource.kernel@...o.com>
Subject: Re: [PATCH v2 2/4] udmabuf: change folios array from kmalloc to
kvmalloc
在 2024/8/10 9:29, Kasireddy, Vivek 写道:
> [Some people who received this message don't often get email from vivek.kasireddy@...el.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> Hi Huan,
>
>> When PAGE_SIZE 4096, MAX_PAGE_ORDER 10, 64bit machine,
>> page_alloc only support 4MB.
>> If above this, trigger this warn and return NULL.
>>
>> udmabuf can change size limit, if change it to 3072(3GB), and then alloc
>> 3GB udmabuf, will fail create.
>>
>> [ 4080.876581] ------------[ cut here ]------------
>> [ 4080.876843] WARNING: CPU: 3 PID: 2015 at mm/page_alloc.c:4556
>> __alloc_pages+0x2c8/0x350
>> [ 4080.878839] RIP: 0010:__alloc_pages+0x2c8/0x350
>> [ 4080.879470] Call Trace:
>> [ 4080.879473] <TASK>
>> [ 4080.879473] ? __alloc_pages+0x2c8/0x350
>> [ 4080.879475] ? __warn.cold+0x8e/0xe8
>> [ 4080.880647] ? __alloc_pages+0x2c8/0x350
>> [ 4080.880909] ? report_bug+0xff/0x140
>> [ 4080.881175] ? handle_bug+0x3c/0x80
>> [ 4080.881556] ? exc_invalid_op+0x17/0x70
>> [ 4080.881559] ? asm_exc_invalid_op+0x1a/0x20
>> [ 4080.882077] ? udmabuf_create+0x131/0x400
>>
>> Because MAX_PAGE_ORDER, kmalloc can max alloc 4096 * (1 << 10), 4MB
>> memory, each array entry is pointer(8byte), so can save 524288 pages(2GB).
>>
>> Further more, costly order(order 3) may not be guaranteed that it can be
>> applied for, due to fragmentation.
>>
>> This patch change udmabuf array use kvmalloc_array, this can fallback
>> alloc into vmalloc, which can guarantee allocation for any size and does
>> not affect the performance of kmalloc allocations.
>>
>> Signed-off-by: Huan Yang <link@...o.com>
>> Acked-by: Christian König <christian.koenig@....com>
>> ---
>> drivers/dma-buf/udmabuf.c | 26 +++++++++++++-------------
>> 1 file changed, 13 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
>> index 475268d4ebb1..af2391cea0bf 100644
>> --- a/drivers/dma-buf/udmabuf.c
>> +++ b/drivers/dma-buf/udmabuf.c
>> @@ -73,7 +73,7 @@ static int vmap_udmabuf(struct dma_buf *buf, struct
>> iosys_map *map)
>>
>> dma_resv_assert_held(buf->resv);
>>
>> - pages = kmalloc_array(ubuf->pagecount, sizeof(*pages),
>> GFP_KERNEL);
>> + pages = kvmalloc_array(ubuf->pagecount, sizeof(*pages),
>> GFP_KERNEL);
>> if (!pages)
>> return -ENOMEM;
>>
>> @@ -81,7 +81,7 @@ static int vmap_udmabuf(struct dma_buf *buf, struct
>> iosys_map *map)
>> pages[pg] = &ubuf->folios[pg]->page;
>>
>> vaddr = vm_map_ram(pages, ubuf->pagecount, -1);
>> - kfree(pages);
>> + kvfree(pages);
>> if (!vaddr)
>> return -EINVAL;
>>
>> @@ -189,8 +189,8 @@ static void release_udmabuf(struct dma_buf *buf)
>> put_sg_table(dev, ubuf->sg, DMA_BIDIRECTIONAL);
>>
>> unpin_all_folios(&ubuf->unpin_list);
>> - kfree(ubuf->offsets);
>> - kfree(ubuf->folios);
>> + kvfree(ubuf->offsets);
>> + kvfree(ubuf->folios);
>> kfree(ubuf);
>> }
>>
>> @@ -315,14 +315,14 @@ static long udmabuf_create(struct miscdevice
>> *device,
>> if (!ubuf->pagecount)
>> goto err;
>>
>> - ubuf->folios = kmalloc_array(ubuf->pagecount, sizeof(*ubuf->folios),
>> - GFP_KERNEL);
>> + ubuf->folios = kvmalloc_array(ubuf->pagecount, sizeof(*ubuf-
>>> folios),
>> + GFP_KERNEL);
>> if (!ubuf->folios) {
>> ret = -ENOMEM;
>> goto err;
>> }
>> - ubuf->offsets = kcalloc(ubuf->pagecount, sizeof(*ubuf->offsets),
>> - GFP_KERNEL);
>> + ubuf->offsets =
>> + kvcalloc(ubuf->pagecount, sizeof(*ubuf->offsets),
> No strong opinion, but I'd prefer to keep the kvcalloc on the same line.
> Regardless,
This style is auto formatted by my clang-format with .clang-format set
in kernel.
But, I chang into online:
ubuf->offsets = kvcalloc(ubuf->pagecount, sizeof(*ubuf->offsets),
GFP_KERNEL);
checkpatch also did not report any errors.
So, I can send the next version of the patch when needed.
Thanks.
>
> Acked-by: Vivek Kasireddy <vivek.kasireddy@...el.com>
>
>> GFP_KERNEL);
>> if (!ubuf->offsets) {
>> ret = -ENOMEM;
>> goto err;
>> @@ -336,7 +336,7 @@ static long udmabuf_create(struct miscdevice
>> *device,
>> goto err;
>>
>> pgcnt = list[i].size >> PAGE_SHIFT;
>> - folios = kmalloc_array(pgcnt, sizeof(*folios), GFP_KERNEL);
>> + folios = kvmalloc_array(pgcnt, sizeof(*folios), GFP_KERNEL);
>> if (!folios) {
>> ret = -ENOMEM;
>> goto err;
>> @@ -346,7 +346,7 @@ static long udmabuf_create(struct miscdevice
>> *device,
>> ret = memfd_pin_folios(memfd, list[i].offset, end,
>> folios, pgcnt, &pgoff);
>> if (ret <= 0) {
>> - kfree(folios);
>> + kvfree(folios);
>> if (!ret)
>> ret = -EINVAL;
>> goto err;
>> @@ -375,7 +375,7 @@ static long udmabuf_create(struct miscdevice
>> *device,
>> }
>> }
>>
>> - kfree(folios);
>> + kvfree(folios);
>> fput(memfd);
>> memfd = NULL;
>> }
>> @@ -391,8 +391,8 @@ static long udmabuf_create(struct miscdevice
>> *device,
>> if (memfd)
>> fput(memfd);
>> unpin_all_folios(&ubuf->unpin_list);
>> - kfree(ubuf->offsets);
>> - kfree(ubuf->folios);
>> + kvfree(ubuf->offsets);
>> + kvfree(ubuf->folios);
>> kfree(ubuf);
>> return ret;
>> }
>> --
>> 2.45.2
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