Re: [PATCH v3 1/2] tpm: Use GFP_KERNEL for allocating struct tpm_buf
From: James Bottomley
Date: Fri Oct 11 2019 - 12:04:04 EST
On Thu, 2019-10-10 at 00:36 +0300, Jarkko Sakkinen wrote:
> On Mon, Oct 07, 2019 at 12:12:08PM -0700, 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@xxxxxxxxxxxxxxxxxxx
> > om>
> Pushed to master branch.
Thanks. 0day spotted a problem with the use of free_page() so I've
sent a v2.