[PATCH v3 0/4] arch, mm: improve robustness of direct map manipulation
From: Mike Rapoport <rppt@kernel.org>
Date: 2020-11-01 17:08:31
Also in:
linux-arm-kernel, linux-mm, linux-pm, linux-riscv, linux-s390, lkml, sparclinux
From: Mike Rapoport <redacted> 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 (local) 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 (local) v1: https://lore.kernel.org/lkml/20201025101555.3057-1-rppt@kernel.org (local) 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(-) -- 2.28.0 *** BLURB HERE *** 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(-) -- 2.28.0