linux-kernel - Re: [PATCH v3 3/8] mm/rmap: Split try_to_munlock from try_to

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Message-ID: <29906974.JcgKRUyaEZ@nvdebian>
Date:   Thu, 4 Mar 2021 15:27:16 +1100
From:   Alistair Popple <apopple@...dia.com>
To:     Jason Gunthorpe <jgg@...dia.com>
CC:     <linux-mm@...ck.org>, <nouveau@...ts.freedesktop.org>,
        <bskeggs@...hat.com>, <akpm@...ux-foundation.org>,
        <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>, <jhubbard@...dia.com>,
        <rcampbell@...dia.com>, <jglisse@...hat.com>, <hch@...radead.org>,
        <daniel@...ll.ch>
Subject: Re: [PATCH v3 3/8] mm/rmap: Split try_to_munlock from try_to_unmap

On Tuesday, 2 March 2021 3:10:49 AM AEDT Jason Gunthorpe wrote:
> > +       while (page_vma_mapped_walk(&pvmw)) {
> > +               /*
> > +                * If the page is mlock()d, we cannot swap it out.
> > +                * If it's recently referenced (perhaps page_referenced
> > +                * skipped over this mm) then we should reactivate it.
> > +                */
> > +               if (vma->vm_flags & VM_LOCKED) {
> 
> And since we write the data without holding the PTLs this looks
> pointless, unless there is some other VM_LOCKED manipulation
> 

Thanks. I couldn't find any other manipulation of VM_LOCKED whilst holding the 
PTL so I'll remove this redundant check.

 - Alistair