From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
"H. Peter Anvin" <hpa@zytor.com>, Andi Kleen <ak@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Andy Lutomirski <luto@amacapital.net>,
linux-arch@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 6/7] mm: convert generic code to 5-level paging
Date: Wed, 8 Mar 2017 18:21:30 +0300 [thread overview]
Message-ID: <20170308152129.sknp75d5usdu4vne@black.fi.intel.com> (raw)
In-Reply-To: <20170308135734.GA11034@dhcp22.suse.cz>
On Wed, Mar 08, 2017 at 02:57:35PM +0100, Michal Hocko wrote:
> On Mon 06-03-17 23:45:13, Kirill A. Shutemov wrote:
> > Convert all non-architecture-specific code to 5-level paging.
> >
> > It's mostly mechanical adding handling one more page table level in
> > places where we deal with pud_t.
> >
> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>
> OK, I haven't spotted anything major. I am just scratching my head about
> the __ARCH_HAS_5LEVEL_HACK leak into kasan_init.c (see below). Why do we
> need it? It looks more than ugly but I am not familiar with kasan so
> maybe this is really necessary.
Yeah ugly.
kasan_zero_p4d is only defined if we have real page table level. It's okay
if the page table level is folded properly -- using pgtable-nop4d.h -- in
this case pgd_populate() is nop and we don't reference kasan_zero_p4d.
With 5level-fixup.h, pgd_populate() is not nop, so we would reference
kasan_zero_p4d and build breaks. We don't need this as p4d_populate()
would do what we really need in this case.
We can drop the hack once all architectures that support kasan would be
converted to pgtable-nop4d.h -- amd64 and x86 at the moment.
Makes sense?
--
Kirill A. Shutemov
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next prev parent reply other threads:[~2017-03-08 15:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-06 20:45 [PATCH 0/7] 5-level paging: prepare generic code Kirill A. Shutemov
2017-03-06 20:45 ` [PATCH 1/7] x86/cpufeature: Add 5-level paging detection Kirill A. Shutemov
2017-03-06 20:45 ` [PATCH 2/7] asm-generic: introduce 5level-fixup.h Kirill A. Shutemov
2017-03-06 20:45 ` [PATCH 3/7] asm-generic: introduce __ARCH_USE_5LEVEL_HACK Kirill A. Shutemov
2017-03-06 20:45 ` [PATCH 4/7] arch, mm: convert all architectures to use 5level-fixup.h Kirill A. Shutemov
2017-03-06 20:45 ` [PATCH 5/7] asm-generic: introduce <asm-generic/pgtable-nop4d.h> Kirill A. Shutemov
2017-03-06 20:45 ` [PATCH 6/7] mm: convert generic code to 5-level paging Kirill A. Shutemov
2017-03-08 13:57 ` Michal Hocko
2017-03-08 15:21 ` Kirill A. Shutemov [this message]
2017-03-09 9:54 ` Michal Hocko
2017-03-09 11:47 ` Kirill A. Shutemov
2017-03-09 12:20 ` Michal Hocko
2017-03-09 13:59 ` Kirill A. Shutemov
2017-03-06 20:45 ` [PATCH 7/7] mm: introduce __p4d_alloc() Kirill A. Shutemov
2017-03-08 14:25 ` [PATCH 0/7] 5-level paging: prepare generic code Michal Hocko
2017-03-08 15:07 ` Kirill A. Shutemov
2017-03-08 15:38 ` Michal Hocko
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