From: Vlastimil Babka <vbabka@suse.cz>
To: Mike Rapoport <rppt@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: 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 Hildenbrand <david@redhat.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@linux.intel.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,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Subject: Re: [PATCH v4 2/4] PM: hibernate: make direct map manipulations more explicit
Date: Wed, 4 Nov 2020 18:40:28 +0100 [thread overview]
Message-ID: <9a0780b4-35f8-0ded-c473-d8ab4a26ade5@suse.cz> (raw)
In-Reply-To: <20201103162057.22916-3-rppt@kernel.org>
On 11/3/20 5:20 PM, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
>
> When DEBUG_PAGEALLOC or ARCH_HAS_SET_DIRECT_MAP is enabled a page may be
> not present in the direct map and has to be explicitly mapped before it
> could be copied.
>
> Introduce hibernate_map_page() that will explicitly use
> set_direct_map_{default,invalid}_noflush() for ARCH_HAS_SET_DIRECT_MAP case
> and debug_pagealloc_map_pages() for DEBUG_PAGEALLOC case.
>
> The remapping of the pages in safe_copy_page() presumes that it only
> changes protection bits in an existing PTE and so it is safe to ignore
> return value of set_direct_map_{default,invalid}_noflush().
>
> Still, add a pr_warn() so that future changes in set_memory APIs will not
> silently break hibernation.
>
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
The bool param is a bit more acceptable here, being a private API. But if
debug_pagealloc_map_pages() becomes split, then it might be easier to split this
one too...
> ---
> include/linux/mm.h | 12 ------------
> kernel/power/snapshot.c | 32 ++++++++++++++++++++++++++++++--
> 2 files changed, 30 insertions(+), 14 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 1fc0609056dc..14e397f3752c 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2927,16 +2927,6 @@ 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)
> -{
> - __kernel_map_pages(page, numpages, enable);
> -}
> -
> static inline void debug_pagealloc_map_pages(struct page *page,
> int numpages, int enable)
> {
> @@ -2948,8 +2938,6 @@ static inline void debug_pagealloc_map_pages(struct page *page,
> 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
> diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
> index 46b1804c1ddf..57d54b9d84bb 100644
> --- a/kernel/power/snapshot.c
> +++ b/kernel/power/snapshot.c
> @@ -76,6 +76,34 @@ 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 */
>
> +static inline void hibernate_map_page(struct page *page, int enable)
> +{
> + if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) {
> + unsigned long addr = (unsigned long)page_address(page);
> + int ret;
> +
> + /*
> + * This should not fail because remapping a page here means
> + * that we only update protection bits in an existing PTE.
> + * It is still worth to have a warning here if something
> + * changes and this will no longer be the case.
> + */
> + if (enable)
> + ret = set_direct_map_default_noflush(page);
> + else
> + ret = set_direct_map_invalid_noflush(page);
> +
> + if (ret) {
> + pr_warn_once("Failed to remap page\n");
> + return;
> + }
> +
> + flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
> + } else {
> + debug_pagealloc_map_pages(page, 1, enable);
> + }
> +}
> +
> static int swsusp_page_is_free(struct page *);
> static void swsusp_set_page_forbidden(struct page *);
> static void swsusp_unset_page_forbidden(struct page *);
> @@ -1355,9 +1383,9 @@ static void safe_copy_page(void *dst, struct page *s_page)
> if (kernel_page_present(s_page)) {
> do_copy_page(dst, page_address(s_page));
> } else {
> - kernel_map_pages(s_page, 1, 1);
> + hibernate_map_page(s_page, 1);
> do_copy_page(dst, page_address(s_page));
> - kernel_map_pages(s_page, 1, 0);
> + hibernate_map_page(s_page, 0);
> }
> }
>
>
next prev parent reply other threads:[~2020-11-04 17:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-03 16:20 [PATCH v4 0/4] arch, mm: improve robustness of direct map manipulation Mike Rapoport
2020-11-03 16:20 ` [PATCH v4 1/4] mm: introduce debug_pagealloc_map_pages() helper Mike Rapoport
2020-11-04 17:35 ` Vlastimil Babka
2020-11-05 11:31 ` Mike Rapoport
2020-11-03 16:20 ` [PATCH v4 2/4] PM: hibernate: make direct map manipulations more explicit Mike Rapoport
2020-11-04 17:40 ` Vlastimil Babka [this message]
2020-11-05 11:33 ` Mike Rapoport
2020-11-03 16:20 ` [PATCH v4 3/4] arch, mm: restore dependency of __kernel_map_pages() of DEBUG_PAGEALLOC Mike Rapoport
2020-11-04 18:02 ` Vlastimil Babka
2020-11-05 11:42 ` Mike Rapoport
2020-11-03 16:20 ` [PATCH v4 4/4] arch, mm: make kernel_page_present() always available Mike Rapoport
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