From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: linux-integrity@vger.kernel.org,
open list <linux-kernel@vger.kernel.org>,
Jerry Snitselaar <jsnitsel@redhat.com>
Subject: Re: [PATCH v2] tpm: use GFP kernel for tpm_buf allocations
Date: Mon, 14 Oct 2019 22:32:24 +0300 [thread overview]
Message-ID: <20191014193224.GF15552@linux.intel.com> (raw)
In-Reply-To: <1570809779.24157.1.camel@HansenPartnership.com>
On Fri, Oct 11, 2019 at 09:02:59AM -0700, James Bottomley wrote:
> 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)
> Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
I'll apply this without a fixes tag as there is no failing system.
Agree that it was not the best design decision to use GFP_HIGHMEM.
/Jarkko
next prev parent reply other threads:[~2019-10-14 19:32 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-11 16:02 [PATCH v2] tpm: use GFP kernel for tpm_buf allocations James Bottomley
2019-10-14 19:32 ` Jarkko Sakkinen [this message]
2019-10-14 19:35 ` James Bottomley
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