linux-kernel - Re: [PATCH AUTOSEL 13/14] mm/thp: ClearPageDoubleMap in first page_add_file

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Date:   Fri, 29 Apr 2022 14:13:02 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Hugh Dickins <hughd@...gle.com>, stable@...r.kernel.org,
        linux-kernel@...r.kernel.org, Yang Shi <shy828301@...il.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-mm@...ck.org, Sasha Levin <sashal@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH AUTOSEL 13/14] mm/thp: ClearPageDoubleMap in first
 page_add_file_rmap()

On Thu, Apr 28, 2022 at 10:45:18PM +0000, Sean Christopherson wrote:
> +Sasha and Paolo
> 
> On Thu, Apr 28, 2022, Hugh Dickins wrote:
> > On Thu, 28 Apr 2022, Greg Kroah-Hartman wrote:
> > > On Thu, Apr 28, 2022 at 09:51:58AM -0700, Hugh Dickins wrote:
> > > > On Thu, 28 Apr 2022, Greg Kroah-Hartman wrote:
> > > > 
> > > > > From: Hugh Dickins <hughd@...gle.com>
> > > > > 
> > > > > commit bd55b0c2d64e84a75575f548a33a3dfecc135b65 upstream.
> > > > > 
> > > > > PageDoubleMap is maintained differently for anon and for shmem+file: the
> > > > > shmem+file one was never cleared, because a safe place to do so could
> > > > > not be found; so it would blight future use of the cached hugepage until
> > > > > evicted.
> > > > > 
> > > > > See https://lore.kernel.org/lkml/1571938066-29031-1-git-send-email-yang.shi@linux.alibaba.com/
> > > > > 
> > > > > But page_add_file_rmap() does provide a safe place to do so (though later
> > > > > than one might wish): allowing testing to return to an initial state
> > > > > without a damaging drop_caches.
> > > > > 
> > > > > Link: https://lkml.kernel.org/r/61c5cf99-a962-9a25-597a-53ab1bd8fbc0@google.com
> > > > > Fixes: 9a73f61bdb8a ("thp, mlock: do not mlock PTE-mapped file huge pages")
> > > > > Signed-off-by: Hugh Dickins <hughd@...gle.com>
> > > > > Reviewed-by: Yang Shi <shy828301@...il.com>
> > > > > Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
> > > > > Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> > > > > Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
> > > > > Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> > > > 
> > > > NAK.
> > > > 
> > > > I thought we had a long-standing agreement that AUTOSEL does not try
> > > > to add patches from akpm's tree which had not been marked for stable.
> > > 
> > > True, this was my attempt at saying "hey these all look like they should
> > > go to stable trees, why not?"
> > 
> > Okay, it seems I should have read "AUTOSEL" as "Hey, GregKH here,
> > these all look like they should go to stable trees, why not?",
> > which would have drawn a friendlier response.
> 
> FWIW, Sasha has been using MANUALSEL for the KVM tree to solicit an explicit ACK
> from Paolo for these types of patches.  AFAICT, it has been working quite well.

Yes, that is what I should have put here, sorry about that.  These were
manually picked by me and I am asking if they should be included or not.
I'll resend after dropping Hugh's patches from the series.

thanks,

greg k-h