linux-kernel - RE: [PATCH V2 5/6] x86/mm: If in_atomic(), allocate pages without sleeping

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Date:   Mon, 3 Sep 2018 17:07:03 +0000
From:   "Prakhya, Sai Praneeth" <sai.praneeth.prakhya@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>
CC:     "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Neri, Ricardo" <ricardo.neri@...el.com>,
        "matt@...eblueprint.co.uk" <matt@...eblueprint.co.uk>,
        Lee Chun-Yi <jlee@...e.com>, Al Stone <astone@...hat.com>,
        Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Bhupesh Sharma <bhsharma@...hat.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: RE: [PATCH V2 5/6] x86/mm: If in_atomic(), allocate pages without
 sleeping

> Thanks for CC'ing me. I wonder why the world and some more is on CC, but
> x86@...nel.org is NOT.
>

Sorry! about that. I will CC you and x86 from V3.

> > On Sun, Sep 02, 2018 at 02:46:33AM -0700, Sai Praneeth Prakhya wrote:
> 
> > > @@ -926,7 +926,13 @@ static void unmap_pud_range(p4d_t *p4d,
> > > unsigned long start, unsigned long end)
> > >
> > >  static int alloc_pte_page(pmd_t *pmd)  {
> > > -	pte_t *pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
> > > +	pte_t *pte;
> > > +
> > > +	if (in_atomic())
> > > +		pte = (pte_t *)get_zeroed_page(GFP_ATOMIC);
> > > +	else
> > > +		pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
> > > +
> > >  	if (!pte)
> > >  		return -1;
> > >
> >
> > This looks like tinkering to me..
> 
> Yes it is and it's not going to happen.

Haha.. ok.. I will take your suggestion in the 4th patch and that should avoid this.

Regards,
Sai