Messages in this thread Patch in this message | | | From | Miles Chen <> | Subject | [PATCH] gfp: further document GFP_DMA32 | Date | Tue, 7 Dec 2021 17:36:10 +0800 |
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kmalloc(..., GFP_DMA32) does not return DMA32 memory because the DMA32 kmalloc cache array is not implemented. (Reason: there is no such user in kernel).
Put a short comment about this so people can understand this by reading the comment.
[1] https://lists.linuxfoundation.org/pipermail/iommu/2018-December/031696.html
Signed-off-by: Miles Chen <miles.chen@mediatek.com> --- include/linux/gfp.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/include/linux/gfp.h b/include/linux/gfp.h index b976c4177299..c7bfaa9f3903 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -302,7 +302,9 @@ struct vm_area_struct; * lowest zone as a type of emergency reserve. * * %GFP_DMA32 is similar to %GFP_DMA except that the caller requires a 32-bit - * address. + * address. Note that kmalloc(..., GFP_DMA32) does not return DMA32 memory + * because the DMA32 kmalloc cache array is not implemented. + * (Reason: there is no such user in kernel). * * %GFP_HIGHUSER is for userspace allocations that may be mapped to userspace, * do not need to be directly accessible by the kernel but that cannot -- 2.18.0
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