linux-kernel - Re: [PATCH v2 13/35] x86/mm: attempt speculative mm faults first

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Date:   Mon, 7 Feb 2022 09:39:31 -0800
From:   Michel Lespinasse <michel@...pinasse.org>
To:     Liam Howlett <liam.howlett@...cle.com>
Cc:     Michel Lespinasse <michel@...pinasse.org>,
        Linux-MM <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "kernel-team@...com" <kernel-team@...com>,
        Laurent Dufour <ldufour@...ux.ibm.com>,
        Jerome Glisse <jglisse@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Davidlohr Bueso <dave@...olabs.net>,
        Matthew Wilcox <willy@...radead.org>,
        Rik van Riel <riel@...riel.com>,
        Paul McKenney <paulmck@...nel.org>,
        Song Liu <songliubraving@...com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Minchan Kim <minchan@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>,
        David Rientjes <rientjes@...gle.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH v2 13/35] x86/mm: attempt speculative mm faults first

On Tue, Feb 01, 2022 at 05:16:43PM +0000, Liam Howlett wrote:
> > +	vma = __find_vma(mm, address);
> > +	if (!vma || vma->vm_start > address) {
> 
> This fits the vma_lookup() pattern - although you will have to work
> around the locking issue still.  This is the same for the other
> platforms too; they fit the pattern also.

In this case, I think it's just as well to follow the lines of the
non-speculative path, which itself can't use vma_lookup() because it
needs to handle the stack expansion case...

--
Michel "walken" Lespinasse