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From: Mimi Zohar <zohar@linux.ibm.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: linux-integrity@vger.kernel.org,
	Jerry Snitselaar <jsnitsel@redhat.com>,
	Sumit Garg <sumit.garg@linaro.org>,
	Stefan Berger <stefanb@linux.vnet.ibm.com>,
	Peter Huewe <peterhuewe@gmx.de>, Jason Gunthorpe <jgg@ziepe.ca>,
	Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] tpm: Detach page allocation from tpm_buf
Date: Wed, 02 Oct 2019 08:41:45 -0400	[thread overview]
Message-ID: <1570020105.4999.106.camel@linux.ibm.com> (raw)
In-Reply-To: <20190927130657.GA5556@linux.intel.com>

On Fri, 2019-09-27 at 16:06 +0300, Jarkko Sakkinen wrote:
> On Wed, Sep 25, 2019 at 10:03:46AM -0400, James Bottomley wrote:
> > On Wed, 2019-09-25 at 16:48 +0300, Jarkko Sakkinen wrote:
> > [...]
> > > +	data_page = alloc_page(GFP_HIGHUSER);
> > > +	if (!data_page)
> > > +		return -ENOMEM;
> > > +
> > > +	data_ptr = kmap(data_page);
> > 
> > I don't think this is such a good idea.  On 64 bit it's no different
> > from GFP_KERNEL and on 32 bit where we do have highmem, kmap space is
> > at a premium, so doing a highmem allocation + kmap is more wasteful of
> > resources than simply doing GFP_KERNEL.  In general, you should only do
> > GFP_HIGHMEM if the page is going to be mostly used by userspace, which
> > really isn't the case here.
> 
> Changing that in this commit would be wrong even if you are right.
> After this commit has been applied it is somewhat easier to make
> best choices for allocation in each call site (probably most will
> end up using stack).

Agreed, but it could be a separate patch, prior to this one.  Why
duplicate the problem all over only to change it later?

Mimi


  reply	other threads:[~2019-10-02 12:41 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-25 13:48 Jarkko Sakkinen
2019-09-25 14:03 ` James Bottomley
2019-09-27 13:06   ` Jarkko Sakkinen
2019-10-02 12:41     ` Mimi Zohar [this message]
2019-10-03 11:35       ` Jarkko Sakkinen
2019-10-03 12:50         ` Mimi Zohar
2019-10-03 18:26           ` Jarkko Sakkinen
2019-09-26 12:46 ` Jarkko Sakkinen
2019-09-26 13:12   ` Jarkko Sakkinen
2019-10-02 12:40     ` Mimi Zohar
2019-10-03 11:32       ` Jarkko Sakkinen
2019-10-03 11:33         ` Jarkko Sakkinen
2019-10-03 15:24           ` Mimi Zohar
2019-10-03 18:33             ` Jarkko Sakkinen
2019-10-03 12:39         ` Mimi Zohar
2019-10-03 18:31           ` Jarkko Sakkinen
2019-09-26 17:23 Jarkko Sakkinen
2019-09-27 15:42 ` Jarkko Sakkinen
2019-09-28  7:58 ` Jerry Snitselaar
2019-10-01 20:51   ` Jarkko Sakkinen

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