| Message ID | 20201101170815.9795-1-rppt@kernel.org |
|---|---|
| Headers | show |
| Series | arch, mm: improve robustness of direct map manipulation | expand |
> int __init kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, unsigned long address, > unsigned numpages, unsigned long page_flags) > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 14e397f3752c..ab0ef6bd351d 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2924,7 +2924,11 @@ static inline bool debug_pagealloc_enabled_static(void) > return static_branch_unlikely(&_debug_pagealloc_enabled); > } > > -#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_ARCH_HAS_SET_DIRECT_MAP) > +#ifdef CONFIG_DEBUG_PAGEALLOC > +/* > + * To support DEBUG_PAGEALLOC architecture must ensure that > + * __kernel_map_pages() never fails Maybe add here, that this implies mapping everything via PTEs during boot. Acked-by: David Hildenbrand <david@redhat.com> -- Thanks, David / dhildenb
On Mon, Nov 02, 2020 at 10:23:20AM +0100, David Hildenbrand wrote: > > > int __init kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, unsigned long address, > > unsigned numpages, unsigned long page_flags) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > index 14e397f3752c..ab0ef6bd351d 100644 > > --- a/include/linux/mm.h > > +++ b/include/linux/mm.h > > @@ -2924,7 +2924,11 @@ static inline bool debug_pagealloc_enabled_static(void) > > return static_branch_unlikely(&_debug_pagealloc_enabled); > > } > > -#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_ARCH_HAS_SET_DIRECT_MAP) > > +#ifdef CONFIG_DEBUG_PAGEALLOC > > +/* > > + * To support DEBUG_PAGEALLOC architecture must ensure that > > + * __kernel_map_pages() never fails > > Maybe add here, that this implies mapping everything via PTEs during boot. This is more of an implementation detail, while assumption that __kernel_map_pages() does not fail is somewhat a requirement :) > Acked-by: David Hildenbrand <david@redhat.com> Thanks! > -- > Thanks, > > David / dhildenb > -- Sincerely yours, Mike.
On Sun, Nov 01, 2020 at 07:08:11PM +0200, Mike Rapoport wrote: > Mike Rapoport (4): > mm: introduce debug_pagealloc_map_pages() helper > PM: hibernate: make direct map manipulations more explicit > arch, mm: restore dependency of __kernel_map_pages() of DEBUG_PAGEALLOC > arch, mm: make kernel_page_present() always available The series looks good to me (apart from the minor nit): Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> -- Kirill A. Shutemov
From: Mike Rapoport <rppt@linux.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, it is updated to make direct map accesses there more explicit. [1] https://lore.kernel.org/lkml/2759b4bf-e1e3-d006-7d86-78a40348269d@redhat.com v3 changes: * update arm64 changes to avoid regression, per Rick's comments * fix bisectability 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_pages() helper PM: hibernate: make direct map manipulations more explicit arch, mm: restore dependency of __kernel_map_pages() of 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 | 35 +++++++++++++---------------- include/linux/set_memory.h | 5 +++++ kernel/power/snapshot.c | 30 +++++++++++++++++++++++-- mm/memory_hotplug.c | 3 +-- mm/page_alloc.c | 6 ++--- mm/slab.c | 8 +++---- 20 files changed, 103 insertions(+), 58 deletions(-)