From: Mike Rapoport <rppt@kernel.org>
To: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Albert Ou <aou@eecs.berkeley.edu>,
Andy Lutomirski <luto@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Borislav Petkov <bp@alien8.de>,
Catalin Marinas <catalin.marinas@arm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Christoph Lameter <cl@linux.com>,
"David S. Miller" <davem@davemloft.net>,
Dave Hansen <dave.hansen@linux.intel.com>,
David Rientjes <rientjes@google.com>,
"Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Heiko Carstens <hca@linux.ibm.com>,
Ingo Molnar <mingo@redhat.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Len Brown <len.brown@intel.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Mike Rapoport <rppt@linux.ibm.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Mackerras <paulus@samba.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Pavel Machek <pavel@ucw.cz>, Pekka Enberg <penberg@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Thomas Gleixner <tglx@linutronix.de>,
Vasily Gorbik <gor@linux.ibm.com>, Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-pm@vger.kernel.org, linux-riscv@lists.infradead.org,
linux-s390@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
sparclinux@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH 1/4] mm: introduce debug_pagealloc_map_pages() helper
Date: Mon, 26 Oct 2020 13:54:43 +0200 [thread overview]
Message-ID: <20201026115443.GF1154158@kernel.org> (raw)
In-Reply-To: <8720c067-7dc5-2b02-918b-e54dd642bfd6@redhat.com>
On Mon, Oct 26, 2020 at 12:05:13PM +0100, David Hildenbrand wrote:
> On 25.10.20 11:15, Mike Rapoport wrote:
> > From: Mike Rapoport <rppt@linux.ibm.com>
> >
> > When CONFIG_DEBUG_PAGEALLOC is enabled, it unmaps pages from the
> > kernel direct mapping after free_pages(). The pages than need to be
> > mapped back before they could be used. Theese mapping operations use
> > __kernel_map_pages() guarded with with debug_pagealloc_enabled().
> >
> > The only place that calls __kernel_map_pages() without checking
> > whether DEBUG_PAGEALLOC is enabled is the hibernation code that
> > presumes availability of this function when ARCH_HAS_SET_DIRECT_MAP
> > is set. Still, on arm64, __kernel_map_pages() will bail out when
> > DEBUG_PAGEALLOC is not enabled but set_direct_map_invalid_noflush()
> > may render some pages not present in the direct map and hibernation
> > code won't be able to save such pages.
> >
> > To make page allocation debugging and hibernation interaction more
> > robust, the dependency on DEBUG_PAGEALLOC or ARCH_HAS_SET_DIRECT_MAP
> > has to be made more explicit.
> >
> > Start with combining the guard condition and the call to
> > __kernel_map_pages() into a single debug_pagealloc_map_pages()
> > function to emphasize that __kernel_map_pages() should not be called
> > without DEBUG_PAGEALLOC and use this new function to map/unmap pages
> > when page allocation debug is enabled.
> >
> > As the only remaining user of kernel_map_pages() is the hibernation
> > code, mode that function into kernel/power/snapshot.c closer to a
> > caller.
>
> s/mode/move/
>
> >
> > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> ---
> > include/linux/mm.h | 16 +++++++--------- kernel/power/snapshot.c
> > | 11 +++++++++++ mm/memory_hotplug.c | 3 +-- mm/page_alloc.c
> > | 6 ++---- mm/slab.c | 8 +++----- 5 files changed, 24
> > insertions(+), 20 deletions(-)
> >
> > diff --git a/include/linux/mm.h b/include/linux/mm.h index
> > ef360fe70aaf..14e397f3752c 100644 --- a/include/linux/mm.h +++
> > b/include/linux/mm.h @@ -2927,21 +2927,19 @@ static inline bool
> > debug_pagealloc_enabled_static(void) #if
> > defined(CONFIG_DEBUG_PAGEALLOC) ||
> > defined(CONFIG_ARCH_HAS_SET_DIRECT_MAP) extern void
> > __kernel_map_pages(struct page *page, int numpages, int enable);
> >
> > -/* - * When called in DEBUG_PAGEALLOC context, the call should most
> > likely be - * guarded by debug_pagealloc_enabled() or
> > debug_pagealloc_enabled_static() - */ -static inline void
> > -kernel_map_pages(struct page *page, int numpages, int enable)
> > +static inline void debug_pagealloc_map_pages(struct page *page, +
> > int numpages, int enable) { - __kernel_map_pages(page, numpages,
> > enable); + if (debug_pagealloc_enabled_static()) +
> > __kernel_map_pages(page, numpages, enable); } + #ifdef
> > CONFIG_HIBERNATION extern bool kernel_page_present(struct page
> > *page); #endif /* CONFIG_HIBERNATION */ #else /*
> > CONFIG_DEBUG_PAGEALLOC || CONFIG_ARCH_HAS_SET_DIRECT_MAP */ -static
> > inline void -kernel_map_pages(struct page *page, int numpages, int
> > enable) {} +static inline void debug_pagealloc_map_pages(struct page
> > *page, + int numpages, int enable) {} #ifdef
> > CONFIG_HIBERNATION static inline bool kernel_page_present(struct page
> > *page) { return true; } #endif /* CONFIG_HIBERNATION */ diff --git
> > a/kernel/power/snapshot.c b/kernel/power/snapshot.c index
> > 46b1804c1ddf..fa499466f645 100644 --- a/kernel/power/snapshot.c +++
> > b/kernel/power/snapshot.c @@ -76,6 +76,17 @@ static inline void
> > hibernate_restore_protect_page(void *page_address) {} static inline
> > void hibernate_restore_unprotect_page(void *page_address) {} #endif
> > /* CONFIG_STRICT_KERNEL_RWX && CONFIG_ARCH_HAS_SET_MEMORY */
> >
> > +#if defined(CONFIG_DEBUG_PAGEALLOC) ||
> > defined(CONFIG_ARCH_HAS_SET_DIRECT_MAP) +static inline void
> > +kernel_map_pages(struct page *page, int numpages, int enable) +{ +
> > __kernel_map_pages(page, numpages, enable); +} +#else +static inline
> > void +kernel_map_pages(struct page *page, int numpages, int enable)
> > {} +#endif +
>
> That change should go into a separate patch.
Hmm, I beleive you refer to moving kernel_map_pages() to snapshot.c,
right?
> For the debug_pagealloc_map_pages() parts
>
> Reviewed-by: David Hildenbrand <david@redhat.com>
Thanks!
> --
> Thanks,
>
> David / dhildenb
>
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2020-10-26 11:55 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-25 10:15 [PATCH 0/4] arch, mm: improve robustness of direct map manipulation Mike Rapoport
2020-10-25 10:15 ` [PATCH 1/4] mm: introduce debug_pagealloc_map_pages() helper Mike Rapoport
2020-10-26 11:05 ` David Hildenbrand
2020-10-26 11:54 ` Mike Rapoport [this message]
2020-10-26 11:55 ` David Hildenbrand
2020-10-25 10:15 ` [PATCH 2/4] PM: hibernate: improve robustness of mapping pages in the direct map Mike Rapoport
2020-10-26 0:38 ` Edgecombe, Rick P
2020-10-26 9:15 ` Mike Rapoport
2020-10-26 18:57 ` Edgecombe, Rick P
2020-10-27 8:49 ` Mike Rapoport
2020-10-27 22:44 ` Edgecombe, Rick P
2020-10-28 9:41 ` Mike Rapoport
2020-10-27 1:10 ` Edgecombe, Rick P
2020-10-28 21:15 ` Edgecombe, Rick P
2020-10-29 7:54 ` Mike Rapoport
2020-10-29 23:19 ` Edgecombe, Rick P
2020-11-01 17:02 ` Mike Rapoport
2020-10-25 10:15 ` [PATCH 3/4] arch, mm: restore dependency of __kernel_map_pages() of DEBUG_PAGEALLOC Mike Rapoport
2020-10-25 10:15 ` [PATCH 4/4] arch, mm: make kernel_page_present() always available Mike Rapoport
2020-10-26 0:54 ` Edgecombe, Rick P
2020-10-26 9:31 ` Mike Rapoport
2020-10-26 1:13 ` [PATCH 0/4] arch, mm: improve robustness of direct map manipulation Edgecombe, Rick P
2020-10-26 9:05 ` Mike Rapoport
2020-10-26 18:05 ` Edgecombe, Rick P
2020-10-27 8:38 ` Mike Rapoport
2020-10-27 8:46 ` David Hildenbrand
2020-10-27 9:47 ` Mike Rapoport
2020-10-27 10:34 ` David Hildenbrand
2020-10-28 11:09 ` Mike Rapoport
2020-10-28 11:17 ` David Hildenbrand
2020-10-28 12:22 ` Mike Rapoport
2020-10-28 18:31 ` Edgecombe, Rick P
2020-10-28 11:20 ` Will Deacon
2020-10-28 11:30 ` Mike Rapoport
2020-10-28 21:03 ` Edgecombe, Rick P
2020-10-29 8:12 ` Mike Rapoport
2020-10-29 23:19 ` Edgecombe, Rick P
2020-10-29 8:15 ` David Hildenbrand
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