From: Andrew Morton <akpm@linux-foundation.org>
To: "Thomas Hellström" <thomas_os@shipmail.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Thomas Hellstrom <thellstrom@vmware.com>,
Arnd Bergmann <arnd@arndb.de>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH 2/2] mm: Fix a huge pud insertion race during faulting
Date: Mon, 18 Nov 2019 13:02:49 -0800 [thread overview]
Message-ID: <20191118130249.2ec96ffdf9a1aeb4f3e820dd@linux-foundation.org> (raw)
In-Reply-To: <b8600932-517d-99d3-90b4-d9b9e8a6f641@shipmail.org>
On Mon, 18 Nov 2019 13:58:04 +0100 Thomas Hellström (VMware) <thomas_os@shipmail.org> wrote:
> >> Is a -stable backport warranted?
> > I believe it is.
>
> Note that this was caught during a code audit rather than a real
> experienced problem. It looks to me like the only implementation that
> currently creates huge pud pagetable entries is dev_dax_huge_fault()
> which doesn't appear to care much about private (COW) mappings or
> write-tracking which is, I believe, a prerequisite for create_huge_pud()
> falling back on thread 1, but not in thread 2.
>
> This means (assuming that's intentional) that a stable backport
> shouldn't be needed.
>
> For the WIP huge page support for graphics memory we'll be allowing both
> COW mappings and write-tracking, though, but that's still some time away.
>
> In any case, I think this patch needs -rc testing to catch potential
> pud_devmap issues before submitted to stable.
OK, thanks, I'll queue it for 5.5-rc1 with a -stable tag. Hopefully
that way it will get a bit of exposure before the stable trees pick it
up. Maybe this is optimistic..
prev parent reply other threads:[~2019-11-18 21:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-15 11:58 [PATCH 1/2] mm: Move the backup x_devmap() functions to asm-generic/pgtable.h Thomas Hellström (VMware)
2019-11-15 11:58 ` [PATCH 2/2] mm: Fix a huge pud insertion race during faulting Thomas Hellström (VMware)
2019-11-15 19:58 ` Andrew Morton
2019-11-18 10:22 ` Kirill A. Shutemov
2019-11-18 12:58 ` Thomas Hellström (VMware)
2019-11-18 21:02 ` Andrew Morton [this message]
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