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From: Oleg Nesterov <oleg@redhat.com>
To: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Alex Thorlton <athorlton@sgi.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
	viro@zeniv.linux.org.uk, schwidefsky@de.ibm.com,
	rientjes@google.com, riel@redhat.com, pbonzini@redhat.com,
	mingo@kernel.org, mgorman@suse.de,
	kirill.shutemov@linux.intel.com, heiko.carstens@de.ibm.com,
	hannes@cmpxchg.org, ebiederm@xmission.com, aarcange@redhat.com
Subject: Re: + mm-revert-thp-make-madv_hugepage-check-for-mm-def_flags.patch added to -mm tree
Date: Thu, 27 Feb 2014 17:45:24 +0100	[thread overview]
Message-ID: <20140227164524.GB909@redhat.com> (raw)
In-Reply-To: <20140226200535.5fdf4c25@thinkpad>

On 02/26, Gerald Schaefer wrote:
>
> On Wed, 26 Feb 2014 19:06:03 +0100
> Oleg Nesterov <oleg@redhat.com> wrote:
>
> > It would be nice to also change thp_split_mm() to not not play with
> > mm->def_flags, but I am not sure if we can do this.
>
> Hmm, I'm also wondering about this. Basically, we only need VM_NOHUGEPAGE
> in vma->vm_flags, which is done for all existing vmas in thp_split_mm().
> But if there should be new vmas created afterwards, it would still be
> necessary to also have VM_NOHUGEPAGE in mm->def_flags, because the
> vm_flags for new vmas will be set via OR of mm->def_flags, e.g. in
> do_brk() and do_mmap_pgoff().

Yes, exactly, this was my concern.

And while I know nothing about s390, it seems to me that huge pages should
be forbidden for any vma if ->has_pgste was set.

> Anyway, this would then have to be a separate patch, to keep the
> "revertability" of this hack.

Agreed. Thanks!

Oleg.


  reply	other threads:[~2014-02-27 16:46 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <530d2ce9.eikv0ULecNwxF4I5%akpm@linux-foundation.org>
     [not found] ` <530D9F50.1080400@de.ibm.com>
2014-02-26 14:50   ` + mm-revert-thp-make-madv_hugepage-check-for-mm-def_flags.patch added to -mm tree Oleg Nesterov
2014-02-26 15:06     ` Christian Borntraeger
2014-02-26 15:22       ` Kirill A. Shutemov
2014-02-26 15:31       ` Oleg Nesterov
2014-02-26 16:55         ` Gerald Schaefer
2014-02-26 16:57         ` Peter Zijlstra
2014-02-26 17:22           ` Alex Thorlton
2014-02-26 18:06             ` Oleg Nesterov
2014-02-26 19:05               ` Gerald Schaefer
2014-02-27 16:45                 ` Oleg Nesterov [this message]
2014-02-26 19:27               ` Christian Borntraeger
2014-02-26 19:39                 ` Alex Thorlton
2014-02-26 23:24                   ` Andrew Morton
2014-02-27  0:01                     ` Alex Thorlton
2014-02-27 17:26                       ` Alex Thorlton
2014-02-26 20:41               ` Paolo Bonzini
2014-02-27 16:34                 ` Oleg Nesterov
2014-02-26 18:08           ` Oleg Nesterov

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