linux/include/asm-generic/pgtable.h, branch v5.6

mm: add generic p?d_leaf() macros

2020-02-04T03:05:24Z

Patch series "Generic page walk and ptdump", v17. Many architectures current have a debugfs file for dumping the kernel page tables. Currently each architecture has to implement custom functions for this because the details of walking the page tables used by the kernel are different between architectures. This series extends the capabilities of walk_page_range() so that it can deal with the page tables of the kernel (which have no VMAs and can contain larger huge pages than exist for user space). A generic PTDUMP implementation is the implemented making use of the new functionality of walk_page_range() and finally arm64 and x86 are switch to using it, removing the custom table walkers. To enable a generic page table walker to walk the unusual mappings of the kernel we need to implement a set of functions which let us know when the walker has reached the leaf entry. After a suggestion from Will Deacon I've chosen the name p?d_leaf() as this (hopefully) describes the purpose (and is a new name so has no historic baggage). Some architectures have p?d_large macros but this is easily confused with "large pages". This series ends with a generic PTDUMP implemention for arm64 and x86. Mostly this is a clean up and there should be very little functional change. The exceptions are: * arm64 PTDUMP debugfs now displays pages which aren't present (patch 22). * arm64 has the ability to efficiently process KASAN pages (which previously only x86 implemented). This means that the combination of KASAN and DEBUG_WX is now useable. This patch (of 23): Exposing the pud/pgd levels of the page tables to walk_page_range() means we may come across the exotic large mappings that come with large areas of contiguous memory (such as the kernel's linear map). For architectures that don't provide all p?d_leaf() macros, provide generic do nothing default that are suitable where there cannot be leaf pages at that level. Futher patches will add implementations for individual architectures. The name p?d_leaf() is chosen to minimize the confusion with existing uses of "large" pages and "huge" pages which do not necessary mean that the entry is a leaf (for example it may be a set of contiguous entries that only take 1 TLB slot). For the purpose of walking the page tables we don't need to know how it will be represented in the TLB, but we do need to know for sure if it is a leaf of the tree. Link: http://lkml.kernel.org/r/20191218162402.45610-2-steven.price@arm.com Signed-off-by: Steven Price Acked-by: Mark Rutland Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Catalin Marinas Cc: Dave Hansen Cc: Ingo Molnar Cc: James Morse Cc: Jerome Glisse Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Cc: "H. Peter Anvin" Cc: "Liang, Kan" Cc: Albert Ou Cc: Alexandre Ghiti Cc: Benjamin Herrenschmidt Cc: Christian Borntraeger Cc: David S. Miller Cc: Heiko Carstens Cc: James Hogan Cc: Michael Ellerman Cc: Paul Burton Cc: Paul Mackerras Cc: Paul Walmsley Cc: Ralf Baechle Cc: Russell King Cc: Vasily Gorbik Cc: Vineet Gupta Cc: Zong Li Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/memory.c: fix a huge pud insertion race during faulting

2019-12-01T14:29:19Z

A huge pud page can theoretically be faulted in racing with pmd_alloc() in __handle_mm_fault(). That will lead to pmd_alloc() returning an invalid pmd pointer. Fix this by adding a pud_trans_unstable() function similar to pmd_trans_unstable() and check whether the pud is really stable before using the pmd pointer. Race: Thread 1: Thread 2: Comment create_huge_pud() Fallback - not taken. create_huge_pud() Taken. pmd_alloc() Returns an invalid pointer. This will result in user-visible huge page data corruption. Note that this was caught during a code audit rather than a real experienced problem. It looks to me like the only implementation that currently creates huge pud pagetable entries is dev_dax_huge_fault() which doesn't appear to care much about private (COW) mappings or write-tracking which is, I believe, a prerequisite for create_huge_pud() falling back on thread 1, but not in thread 2. Link: http://lkml.kernel.org/r/20191115115808.21181-2-thomas_os@shipmail.org Fixes: a00cc7d9dd93 ("mm, x86: add support for PUD-sized transparent hugepages") Signed-off-by: Thomas Hellstrom Acked-by: Kirill A. Shutemov Cc: Arnd Bergmann Cc: Matthew Wilcox Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: move the backup x_devmap() functions to asm-generic/pgtable.h

2019-12-01T14:29:19Z

The asm-generic/pgtable.h include file appears to be the correct place for the backup x_devmap() inline functions. Moving them here is also necessary if we want to include x_devmap() in the [pmd|pud]_unstable functions. So move the x_devmap() functions to asm-generic/pgtable.h Link: http://lkml.kernel.org/r/20191115115808.21181-1-thomas_os@shipmail.org Signed-off-by: Thomas Hellstrom Cc: Arnd Bergmann Cc: "Kirill A. Shutemov" Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

asm-generic/mm: stub out p{4,u}d_clear_bad() if __PAGETABLE_P{4,U}D_FOLDED

2019-12-01T14:29:19Z

This came up when removing __ARCH_HAS_5LEVEL_HACK for ARC as code bloat. With this patch we see the following code reduction. | bloat-o-meter2 vmlinux-D-elide-p4d_free_tlb vmlinux-E-elide-p?d_clear_bad | add/remove: 0/2 grow/shrink: 0/0 up/down: 0/-40 (-40) | function old new delta | pud_clear_bad 20 - -20 | p4d_clear_bad 20 - -20 | Total: Before=4136930, After=4136890, chg -1.000000% Link: http://lkml.kernel.org/r/20191016162400.14796-6-vgupta@synopsys.com Signed-off-by: Vineet Gupta Acked-by: Kirill A. Shutemov Cc: Arnd Bergmann Cc: Will Deacon Cc: "Aneesh Kumar K . V" Cc: Nick Piggin Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

thp: update split_huge_page_pmd() comment

2019-09-24T22:54:10Z

According to 78ddc5347341 ("thp: rename split_huge_page_pmd() to split_huge_pmd()"), update related comment. Link: http://lkml.kernel.org/r/20190731033406.185285-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Cc: "Kirill A . Shutemov" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: consolidate pgtable_cache_init() and pgd_cache_init()

2019-09-24T22:54:09Z

Both pgtable_cache_init() and pgd_cache_init() are used to initialize kmem cache for page table allocations on several architectures that do not use PAGE_SIZE tables for one or more levels of the page table hierarchy. Most architectures do not implement these functions and use __weak default NOP implementation of pgd_cache_init(). Since there is no such default for pgtable_cache_init(), its empty stub is duplicated among most architectures. Rename the definitions of pgd_cache_init() to pgtable_cache_init() and drop empty stubs of pgtable_cache_init(). Link: http://lkml.kernel.org/r/1566457046-22637-1-git-send-email-rppt@linux.ibm.com Signed-off-by: Mike Rapoport Acked-by: Will Deacon [arm64] Acked-by: Thomas Gleixner [x86] Cc: Catalin Marinas Cc: Ingo Molnar Cc: Borislav Petkov Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

x86/mm: Initialize PGD cache during mm initialization

2019-05-05T18:32:46Z

Poking-mm initialization might require to duplicate the PGD in early stage. Initialize the PGD cache earlier to prevent boot failures. Reported-by: kernel test robot Signed-off-by: Nadav Amit Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Rick Edgecombe Cc: Rik van Riel Cc: Stephen Rothwell Cc: Thomas Gleixner Fixes: 4fc19708b165 ("x86/alternatives: Initialize temporary mm for patching") Link: http://lkml.kernel.org/r/20190505011124.39692-1-namit@vmware.com Signed-off-by: Ingo Molnar

mm: update ptep_modify_prot_commit to take old pte value as arg

2019-03-06T05:07:18Z

Architectures like ppc64 require to do a conditional tlb flush based on the old and new value of pte. Enable that by passing old pte value as the arg. Link: http://lkml.kernel.org/r/20190116085035.29729-3-aneesh.kumar@linux.ibm.com Signed-off-by: Aneesh Kumar K.V Cc: Benjamin Herrenschmidt Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Martin Schwidefsky Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Paul Mackerras Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: update ptep_modify_prot_start/commit to take vm_area_struct as arg

2019-03-06T05:07:18Z

Patch series "NestMMU pte upgrade workaround for mprotect", v5. We can upgrade pte access (R -> RW transition) via mprotect. We need to make sure we follow the recommended pte update sequence as outlined in commit bd5050e38aec ("powerpc/mm/radix: Change pte relax sequence to handle nest MMU hang") for such updates. This patch series does that. This patch (of 5): Some architectures may want to call flush_tlb_range from these helpers. Link: http://lkml.kernel.org/r/20190116085035.29729-2-aneesh.kumar@linux.ibm.com Signed-off-by: Aneesh Kumar K.V Cc: Nicholas Piggin Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: Heiko Carstens Cc: Martin Schwidefsky Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/ioremap: ensure break-before-make is used for huge p4d mappings

2018-12-28T20:11:50Z

Whilst no architectures actually enable support for huge p4d mappings in the vmap area, the code that is implemented should be using break-before-make, as we do for pud and pmd huge entries. Link: http://lkml.kernel.org/r/1544120495-17438-6-git-send-email-will.deacon@arm.com Signed-off-by: Will Deacon Reviewed-by: Toshi Kani Cc: Chintan Pandya Cc: Toshi Kani Cc: Thomas Gleixner Cc: Michal Hocko Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Sean Christopherson Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds