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Date: Mon, 9 Nov 2020 18:47:52 +0200
From: Mike Rapoport <rppt@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Albert Ou <aou@...s.berkeley.edu>,
Andy Lutomirski <luto@...nel.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Borislav Petkov <bp@...en8.de>,
Catalin Marinas <catalin.marinas@....com>,
Christian Borntraeger <borntraeger@...ibm.com>,
Christoph Lameter <cl@...ux.com>,
"David S. Miller" <davem@...emloft.net>,
Dave Hansen <dave.hansen@...ux.intel.com>,
David Hildenbrand <david@...hat.com>,
David Rientjes <rientjes@...gle.com>,
"Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
"H. Peter Anvin" <hpa@...or.com>,
Heiko Carstens <hca@...ux.ibm.com>,
Ingo Molnar <mingo@...hat.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
"Kirill A. Shutemov" <kirill@...temov.name>,
Len Brown <len.brown@...el.com>,
Michael Ellerman <mpe@...erman.id.au>,
Mike Rapoport <rppt@...ux.ibm.com>,
Palmer Dabbelt <palmer@...belt.com>,
Paul Mackerras <paulus@...ba.org>,
Paul Walmsley <paul.walmsley@...ive.com>,
Pavel Machek <pavel@....cz>, Pekka Enberg <penberg@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Thomas Gleixner <tglx@...utronix.de>,
Vasily Gorbik <gor@...ux.ibm.com>,
Vlastimil Babka <vbabka@...e.cz>,
Will Deacon <will@...nel.org>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-pm@...r.kernel.org,
linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org, sparclinux@...r.kernel.org,
x86@...nel.org
Subject: Re: [PATCH v6 0/4] arch, mm: improve robustness of direct map
manipulation
Oops, this one has some rebase errors, I'll send v7 soon.
Sorry for the noise.
On Mon, Nov 09, 2020 at 06:24:11PM +0200, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@...ux.ibm.com>
>
> Hi,
>
> During recent discussion about KVM protected memory, David raised a concern
> about usage of __kernel_map_pages() outside of DEBUG_PAGEALLOC scope [1].
>
> Indeed, for architectures that define CONFIG_ARCH_HAS_SET_DIRECT_MAP it is
> possible that __kernel_map_pages() would fail, but since this function is
> void, the failure will go unnoticed.
>
> Moreover, there's lack of consistency of __kernel_map_pages() semantics
> across architectures as some guard this function with
> #ifdef DEBUG_PAGEALLOC, some refuse to update the direct map if page
> allocation debugging is disabled at run time and some allow modifying the
> direct map regardless of DEBUG_PAGEALLOC settings.
>
> This set straightens this out by restoring dependency of
> __kernel_map_pages() on DEBUG_PAGEALLOC and updating the call sites
> accordingly.
>
> Since currently the only user of __kernel_map_pages() outside
> DEBUG_PAGEALLOC is hibernation, it is updated to make direct map accesses
> there more explicit.
>
> [1] https://lore.kernel.org/lkml/2759b4bf-e1e3-d006-7d86-78a40348269d@redhat.com
>
> v6 changes:
> * revert slab changes to avoid redundant check of static key
>
> v5 changes:
> * use pairs of _map()/_unmap() functions instead of _map(..., int enable) as
> Vlastimil suggested
> https://lore.kernel.org/lkml/20201108065758.1815-1-rppt@kernel.org
>
> v4 changes:
> * s/WARN_ON/pr_warn_once/ per David and Kirill
> * rebase on v5.10-rc2
> * add Acked/Reviewed tags
> https://lore.kernel.org/lkml/20201103162057.22916-1-rppt@kernel.org
>
> v3 changes:
> * update arm64 changes to avoid regression, per Rick's comments
> * fix bisectability
> https://lore.kernel.org/lkml/20201101170815.9795-1-rppt@kernel.org
>
> v2 changes:
> * Rephrase patch 2 changelog to better describe the change intentions and
> implications
> * Move removal of kernel_map_pages() from patch 1 to patch 2, per David
> https://lore.kernel.org/lkml/20201029161902.19272-1-rppt@kernel.org
>
> v1:
> https://lore.kernel.org/lkml/20201025101555.3057-1-rppt@kernel.org
>
> Mike Rapoport (4):
> mm: introduce debug_pagealloc_{map,unmap}_pages() helpers
> PM: hibernate: make direct map manipulations more explicit
> arch, mm: restore dependency of __kernel_map_pages() on DEBUG_PAGEALLOC
> arch, mm: make kernel_page_present() always available
>
> arch/Kconfig | 3 +++
> arch/arm64/Kconfig | 4 +--
> arch/arm64/include/asm/cacheflush.h | 1 +
> arch/arm64/mm/pageattr.c | 6 +++--
> arch/powerpc/Kconfig | 5 +---
> arch/riscv/Kconfig | 4 +--
> arch/riscv/include/asm/pgtable.h | 2 --
> arch/riscv/include/asm/set_memory.h | 1 +
> arch/riscv/mm/pageattr.c | 31 ++++++++++++++++++++++
> arch/s390/Kconfig | 4 +--
> arch/sparc/Kconfig | 4 +--
> arch/x86/Kconfig | 4 +--
> arch/x86/include/asm/set_memory.h | 1 +
> arch/x86/mm/pat/set_memory.c | 4 +--
> include/linux/mm.h | 40 ++++++++++++++---------------
> include/linux/set_memory.h | 5 ++++
> kernel/power/snapshot.c | 38 +++++++++++++++++++++++++--
> mm/memory_hotplug.c | 3 +--
> mm/page_alloc.c | 6 ++---
> 19 files changed, 113 insertions(+), 53 deletions(-)
>
> --
> 2.28.0
>
--
Sincerely yours,
Mike.
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