Re: [PATCH v3 1/2] tpm: Use GFP_KERNEL for allocating struct tpm_buf

From: Jerry Snitselaar
Date: Mon Oct 07 2019 - 19:43:32 EST


On Mon Oct 07 19, James Bottomley wrote:
From: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Subject: [PATCH] tpm: use GFP kernel for tpm_buf allocations

The current code uses GFP_HIGHMEM, which is wrong because GFP_HIGHMEM
(on 32 bit systems) is memory ordinarily inaccessible to the kernel
and should only be used for allocations affecting userspace. In order
to make highmem visible to the kernel on 32 bit it has to be kmapped,
which consumes valuable entries in the kmap region. Since the tpm_buf
is only ever used in the kernel, switch to using a GFP_KERNEL
allocation so as not to waste kmap space on 32 bits.

Fixes: a74f8b36352e (tpm: introduce tpm_buf)
Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
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Reviewed-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>