user/sven/linux.git/include/linux/highmem.h, branch v6.2.7

mm, hwpoison: try to recover from copy-on write faults

2022-11-30T23:58:40Z

Patch series "Copy-on-write poison recovery", v3. Part 1 deals with the process that triggered the copy on write fault with a store to a shared read-only page. That process is send a SIGBUS with the usual machine check decoration to specify the virtual address of the lost page, together with the scope. Part 2 sets up to asynchronously take the page with the uncorrected error offline to prevent additional machine check faults. H/t to Miaohe Lin and Shuai Xue for pointing me to the existing function to queue a call to memory_failure(). On x86 there is some duplicate reporting (because the error is also signalled by the memory controller as well as by the core that triggered the machine check). Console logs look like this: This patch (of 2): If the kernel is copying a page as the result of a copy-on-write fault and runs into an uncorrectable error, Linux will crash because it does not have recovery code for this case where poison is consumed by the kernel. It is easy to set up a test case. Just inject an error into a private page, fork(2), and have the child process write to the page. I wrapped that neatly into a test at: git://git.kernel.org/pub/scm/linux/kernel/git/aegl/ras-tools.git just enable ACPI error injection and run: # ./einj_mem-uc -f copy-on-write Add a new copy_user_highpage_mc() function that uses copy_mc_to_kernel() on architectures where that is available (currently x86 and powerpc). When an error is detected during the page copy, return VM_FAULT_HWPOISON to caller of wp_page_copy(). This propagates up the call stack. Both x86 and powerpc have code in their fault handler to deal with this code by sending a SIGBUS to the application. Note that this patch avoids a system crash and signals the process that triggered the copy-on-write action. It does not take any action for the memory error that is still in the shared page. To handle that a call to memory_failure() is needed. But this cannot be done from wp_page_copy() because it holds mmap_lock(). Perhaps the architecture fault handlers can deal with this loose end in a subsequent patch? On Intel/x86 this loose end will often be handled automatically because the memory controller provides an additional notification of the h/w poison in memory, the handler for this will call memory_failure(). This isn't a 100% solution. If there are multiple errors, not all may be logged in this way. [tony.luck@intel.com: add call to kmsan_unpoison_memory(), per Miaohe Lin] Link: https://lkml.kernel.org/r/20221031201029.102123-2-tony.luck@intel.com Link: https://lkml.kernel.org/r/20221021200120.175753-1-tony.luck@intel.com Link: https://lkml.kernel.org/r/20221021200120.175753-2-tony.luck@intel.com Signed-off-by: Tony Luck Reviewed-by: Dan Williams Reviewed-by: Naoya Horiguchi Reviewed-by: Miaohe Lin Reviewed-by: Alexander Potapenko Tested-by: Shuai Xue Cc: Christophe Leroy Cc: Matthew Wilcox (Oracle) Cc: Michael Ellerman Cc: Nicholas Piggin Signed-off-by: Andrew Morton

mm: kmsan: maintain KMSAN metadata for page operations

2022-10-03T21:03:20Z

Insert KMSAN hooks that make the necessary bookkeeping changes: - poison page shadow and origins in alloc_pages()/free_page(); - clear page shadow and origins in clear_page(), copy_user_highpage(); - copy page metadata in copy_highpage(), wp_page_copy(); - handle vmap()/vunmap()/iounmap(); Link: https://lkml.kernel.org/r/20220915150417.722975-15-glider@google.com Signed-off-by: Alexander Potapenko Cc: Alexander Viro Cc: Alexei Starovoitov Cc: Andrey Konovalov Cc: Andrey Konovalov Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Christoph Hellwig Cc: Christoph Lameter Cc: David Rientjes Cc: Dmitry Vyukov Cc: Eric Biggers Cc: Eric Biggers Cc: Eric Dumazet Cc: Greg Kroah-Hartman Cc: Herbert Xu Cc: Ilya Leoshkevich Cc: Ingo Molnar Cc: Jens Axboe Cc: Joonsoo Kim Cc: Kees Cook Cc: Marco Elver Cc: Mark Rutland Cc: Matthew Wilcox Cc: Michael S. Tsirkin Cc: Pekka Enberg Cc: Peter Zijlstra Cc: Petr Mladek Cc: Stephen Rothwell Cc: Steven Rostedt Cc: Thomas Gleixner Cc: Vasily Gorbik Cc: Vegard Nossum Cc: Vlastimil Babka Signed-off-by: Andrew Morton

highmem: delete a sentence from kmap_local_page() kdocs

2022-08-09T01:06:46Z

kmap_local_page() should always be preferred in place of kmap() and kmap_atomic(). "Only use when really necessary." is not consistent with the Documentation/mm/highmem.rst and these kdocs it embeds. Therefore, delete the above-mentioned sentence from kdocs. Link: https://lkml.kernel.org/r/20220728154844.10874-7-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco Suggested-by: Ira Weiny Reviewed-by: Ira Weiny Cc: Matthew Wilcox (Oracle) Cc: Mike Rapoport Cc: Sebastian Andrzej Siewior Cc: Thomas Gleixner Cc: Catalin Marinas Cc: Jonathan Corbet Cc: Peter Collingbourne Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton

highmem: specify that kmap_local_page() is callable from interrupts

2022-08-09T01:06:45Z

In a recent thread about converting kmap() to kmap_local_page(), the safety of calling kmap_local_page() was questioned.[1] "any context" should probably be enough detail for users who want to know whether or not kmap_local_page() can be called from interrupts. However, Linux still has kmap_atomic() which might make users think they must use the latter in interrupts. Add "including interrupts" for better clarity. [1] https://lore.kernel.org/lkml/3187836.aeNJFYEL58@opensuse/ Link: https://lkml.kernel.org/r/20220728154844.10874-3-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco Suggested-by: Ira Weiny Cc: Matthew Wilcox (Oracle) Cc: Mike Rapoport Cc: Sebastian Andrzej Siewior Cc: Thomas Gleixner Cc: Catalin Marinas Cc: Jonathan Corbet Cc: Peter Collingbourne Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton

highmem: remove unneeded spaces in kmap_local_page() kdocs

2022-08-09T01:06:45Z

Patch series "highmem: Extend kmap_local_page() documentation", v2. The Highmem interface is evolving and the current documentation does not reflect the intended uses of each of the calls. Furthermore, after a recent series of reworks, the differences of the calls can still be confusing and may lead to the expanded use of calls which are deprecated. This series is the second round of changes towards an enhanced documentation of the Highmem's interface; at this stage the patches are only focused to kmap_local_page(). In addition it also contains some minor clean ups. This patch (of 7): In the kdocs of kmap_local_page(), the description of @page starts after several unnecessary spaces. Therefore, remove those spaces. Link: https://lkml.kernel.org/r/20220728154844.10874-1-fmdefrancesco@gmail.com Link: https://lkml.kernel.org/r/20220728154844.10874-2-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco Suggested-by: Ira Weiny Reviewed-by: Ira Weiny Cc: Matthew Wilcox (Oracle) Cc: Mike Rapoport Cc: Sebastian Andrzej Siewior Cc: Thomas Gleixner Cc: Catalin Marinas Cc: Will Deacon Cc: Peter Collingbourne Cc: Vlastimil Babka Cc: Jonathan Corbet Signed-off-by: Andrew Morton

Merge tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-08-05T23:32:45Z

Pull MM updates from Andrew Morton: "Most of the MM queue. A few things are still pending. Liam's maple tree rework didn't make it. This has resulted in a few other minor patch series being held over for next time. Multi-gen LRU still isn't merged as we were waiting for mapletree to stabilize. The current plan is to merge MGLRU into -mm soon and to later reintroduce mapletree, with a view to hopefully getting both into 6.1-rc1. Summary: - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe Lin, Yang Shi, Anshuman Khandual and Mike Rapoport - Some kmemleak fixes from Patrick Wang and Waiman Long - DAMON updates from SeongJae Park - memcg debug/visibility work from Roman Gushchin - vmalloc speedup from Uladzislau Rezki - more folio conversion work from Matthew Wilcox - enhancements for coherent device memory mapping from Alex Sierra - addition of shared pages tracking and CoW support for fsdax, from Shiyang Ruan - hugetlb optimizations from Mike Kravetz - Mel Gorman has contributed some pagealloc changes to improve latency and realtime behaviour. - mprotect soft-dirty checking has been improved by Peter Xu - Many other singleton patches all over the place" [ XFS merge from hell as per Darrick Wong in https://lore.kernel.org/all/YshKnxb4VwXycPO8@magnolia/ ] * tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (282 commits) tools/testing/selftests/vm/hmm-tests.c: fix build mm: Kconfig: fix typo mm: memory-failure: convert to pr_fmt() mm: use is_zone_movable_page() helper hugetlbfs: fix inaccurate comment in hugetlbfs_statfs() hugetlbfs: cleanup some comments in inode.c hugetlbfs: remove unneeded header file hugetlbfs: remove unneeded hugetlbfs_ops forward declaration hugetlbfs: use helper macro SZ_1{K,M} mm: cleanup is_highmem() mm/hmm: add a test for cross device private faults selftests: add soft-dirty into run_vmtests.sh selftests: soft-dirty: add test for mprotect mm/mprotect: fix soft-dirty check in can_change_pte_writable() mm: memcontrol: fix potential oom_lock recursion deadlock mm/gup.c: fix formatting in check_and_migrate_movable_page() xfs: fail dax mount if reflink is enabled on a partition mm/memcontrol.c: remove the redundant updating of stats_flush_threshold userfaultfd: don't fail on unrecognized features hugetlb_cgroup: fix wrong hugetlb cgroup numa stat ...

mm: introduce clear_highpage_kasan_tagged

2022-07-04T01:08:39Z

Add a clear_highpage_kasan_tagged() helper that does clear_highpage() on a page potentially tagged by KASAN. This helper is used by the following patch. Link: https://lkml.kernel.org/r/4471979b46b2c487787ddcd08b9dc5fedd1b6ffd.1654798516.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Marco Elver Signed-off-by: Andrew Morton

Documentation: highmem: use literal block for code example in highmem.h comment

2022-07-03T22:42:32Z

When building htmldocs on Linus's tree, there are inline emphasis warnings on include/linux/highmem.h: Documentation/vm/highmem:166: ./include/linux/highmem.h:154: WARNING: Inline emphasis start-string without end-string. Documentation/vm/highmem:166: ./include/linux/highmem.h:157: WARNING: Inline emphasis start-string without end-string. These warnings above are due to comments in code example at the mentioned lines above are enclosed by double dash (--), which confuses Sphinx as inline markup delimiters instead. Fix these warnings by indenting the code example with literal block indentation and making the comments C comments. Link: https://lkml.kernel.org/r/20220622084546.17745-1-bagasdotme@gmail.com Fixes: 85a85e7601263f ("Documentation/vm: move "Using kmap-atomic" to highmem.h") Signed-off-by: Bagas Sanjaya Reviewed-by: Ira Weiny Tested-by: Ira Weiny Cc: "Matthew Wilcox (Oracle)" Cc: "Fabio M. De Francesco" Cc: Sebastian Andrzej Siewior Signed-off-by: Andrew Morton

mm/highmem: delete memmove_page()

2022-06-17T02:48:29Z

Matthew Wilcox reported that, while he was looking at memmove_page(), he realized that it can't actually work. The reasons are hidden in its implementation, which makes use of memmove() on logical addresses provided by kmap_local_page(). memmove() does the wrong thing when it tests "if (dest <= src)". Therefore, delete memmove_page(). No need to change any other code because we have no call sites of memmove_page() across the whole kernel. Link: https://lkml.kernel.org/r/20220606141533.555-1-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco Reported-by: Matthew Wilcox Reviewed-by: Baoquan He Reviewed-by: Ira Weiny Cc: Sebastian Andrzej Siewior Signed-off-by: Andrew Morton

Documentation/vm: move "Using kmap-atomic" to highmem.h

2022-05-13T23:48:55Z

The use of kmap_atomic() is new code is being deprecated in favor of kmap_local_page(). For this reason the "Using kmap_atomic" section in highmem.rst is obsolete and unnecessary, but it can still help developers if it were moved to kdocs in highmem.h. Therefore, move the relevant parts of this section from highmem.rst and merge them with the kdocs in highmem.h. Link: https://lkml.kernel.org/r/20220428212455.892-4-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco Suggested-by: Ira Weiny Reviewed-by: Sebastian Andrzej Siewior Reviewed-by: Ira Weiny Cc: Jonathan Corbet Cc: Matthew Wilcox Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Catalin Marinas Cc: Mike Rapoport Cc: Peter Collingbourne Cc: Vlastimil Babka Cc: Will Deacon Cc: Jonathan Corbet Signed-off-by: Andrew Morton