kernel/git/stable/linux.git/arch/s390/mm/pgalloc.c, branch master

s390/mm: Simplify crst_table_upgrade()

2026-09-01T10:44:48+00:00

In case of an upgrade from four to five level page tables, and a failing pgd allocation, the exit path of crst_table_upgrade() would incorrectly dereference the p4d NULL pointer via pagetable_dtor(). Address this by reworking crst_table_upgrade(), which basically is a revert of [1]. Take into account that GFP_KERNEL order-2 allocation failures are very unlikely. Therefore keep the code as simple as possible: In case of an upgrade from three to five levels, and an allocation failure of the fifth page table level, keep the upgrade to four levels instead of reverting back to three levels. This allows to keep error handling minimal. [1] commit 31932757c612 ("s390/mm: optimize page table upgrade routine") Reviewed-by: Alexander Gordeev Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens

s390: Remove cond_resched() calls

2026-08-05T13:16:54+00:00

Since [1] cond_resched() is a no-op on s390. Remove all calls. [1] commit 7dadeaa6e851 ("sched: Further restrict the preemption modes") Reviewed-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

KVM: S390: Remove PGSTE code from linux/s390 mm

2026-02-04T16:00:10+00:00

Remove the PGSTE config option. Remove all code from linux/s390 mm that involves PGSTEs. Acked-by: Heiko Carstens Signed-off-by: Claudio Imbrenda

s390/mm: Support removal of boot-allocated virtual memory map

2025-10-14T12:24:53+00:00

On s390, memory blocks are not currently removed via arch_remove_memory(). With upcoming dynamic memory (de)configuration support, runtime removal of memory blocks is possible. This internally involves tearing down identity mapping, virtual memory mappings and freeing the physical memory backing the struct pages metadata. During early boot, physical memory used to back the struct pages metadata in vmemmap is allocated through: setup_arch() -> sparse_init() -> sparse_init_nid() -> __populate_section_memmap() -> vmemmap_alloc_block_buf() -> sparse_buffer_alloc() -> memblock_alloc() Here, sparse_init_nid() sets up virtual-to-physical mapping for struct pages backed by memblock_alloc(). This differs from runtime addition of hotplug memory which uses the buddy allocator later. To correctly free identity mappings, vmemmap mappings during hot-remove, boot-time and runtime allocations must be distinguished using the PageReserved bit: * Boot-time memory, such as identity-mapped page tables allocated via boot_crst_alloc() and reserved via reserve_pgtables() is marked PageReserved in memmap_init_reserved_pages(). * Physical memory backing vmemmap (struct pages from memblock_alloc()) is also marked PageReserved similarly. During teardown, PageReserved bit is checked to distinguish between boot-time allocation or buddy allocation. This is similar to commit 645d5ce2f7d6 ("powerpc/mm/radix: Fix PTE/PMD fragment count for early page table mappings") Reviewed-by: Heiko Carstens Signed-off-by: Sumanth Korikkar Signed-off-by: Heiko Carstens

Merge tag 's390-6.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2025-10-09T17:51:43+00:00

Pull more s390 updates from Alexander Gordeev: - Compile the decompressor with -Wno-pointer-sign flag to avoid a clang warning - Fix incomplete conversion to flag output macros in __xsch(), to avoid always zero return value instead of the expected condition code - Remove superfluous newlines from inline assemblies to improve compiler inlining decisions - Expose firmware provided UID Checking state in sysfs regardless of the device presence or state - CIO does not unregister subchannels when the attached device is invalid or unavailable. Update the purge function to remove I/O subchannels if the device number is found on cio_ignore list - Consolidate PAI crypto allocation and cleanup paths - The uv_get_secret_metadata() function has been removed some few months ago, remove also the function mention it in a comment * tag 's390-6.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: s390/uv: Fix comment of uv_find_secret() function s390/pai_crypto: Consolidate PAI crypto allocation and cleanup paths s390/cio: Update purge function to unregister the unused subchannels s390/pci: Expose firmware provided UID Checking state in sysfs s390: Remove superfluous newlines from inline assemblies s390/cio/ioasm: Fix __xsch() condition code handling s390: Add -Wno-pointer-sign to KBUILD_CFLAGS_DECOMPRESSOR

Merge tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-10-03T01:18:33+00:00

Pull MM updates from Andrew Morton: - "mm, swap: improve cluster scan strategy" from Kairui Song improves performance and reduces the failure rate of swap cluster allocation - "support large align and nid in Rust allocators" from Vitaly Wool permits Rust allocators to set NUMA node and large alignment when perforning slub and vmalloc reallocs - "mm/damon/vaddr: support stat-purpose DAMOS" from Yueyang Pan extend DAMOS_STAT's handling of the DAMON operations sets for virtual address spaces for ops-level DAMOS filters - "execute PROCMAP_QUERY ioctl under per-vma lock" from Suren Baghdasaryan reduces mmap_lock contention during reads of /proc/pid/maps - "mm/mincore: minor clean up for swap cache checking" from Kairui Song performs some cleanup in the swap code - "mm: vm_normal_page*() improvements" from David Hildenbrand provides code cleanup in the pagemap code - "add persistent huge zero folio support" from Pankaj Raghav provides a block layer speedup by optionalls making the huge_zero_pagepersistent, instead of releasing it when its refcount falls to zero - "kho: fixes and cleanups" from Mike Rapoport adds a few touchups to the recently added Kexec Handover feature - "mm: make mm->flags a bitmap and 64-bit on all arches" from Lorenzo Stoakes turns mm_struct.flags into a bitmap. To end the constant struggle with space shortage on 32-bit conflicting with 64-bit's needs - "mm/swapfile.c and swap.h cleanup" from Chris Li cleans up some swap code - "selftests/mm: Fix false positives and skip unsupported tests" from Donet Tom fixes a few things in our selftests code - "prctl: extend PR_SET_THP_DISABLE to only provide THPs when advised" from David Hildenbrand "allows individual processes to opt-out of THP=always into THP=madvise, without affecting other workloads on the system". It's a long story - the [1/N] changelog spells out the considerations - "Add and use memdesc_flags_t" from Matthew Wilcox gets us started on the memdesc project. Please see https://kernelnewbies.org/MatthewWilcox/Memdescs and https://blogs.oracle.com/linux/post/introducing-memdesc - "Tiny optimization for large read operations" from Chi Zhiling improves the efficiency of the pagecache read path - "Better split_huge_page_test result check" from Zi Yan improves our folio splitting selftest code - "test that rmap behaves as expected" from Wei Yang adds some rmap selftests - "remove write_cache_pages()" from Christoph Hellwig removes that function and converts its two remaining callers - "selftests/mm: uffd-stress fixes" from Dev Jain fixes some UFFD selftests issues - "introduce kernel file mapped folios" from Boris Burkov introduces the concept of "kernel file pages". Using these permits btrfs to account its metadata pages to the root cgroup, rather than to the cgroups of random inappropriate tasks - "mm/pageblock: improve readability of some pageblock handling" from Wei Yang provides some readability improvements to the page allocator code - "mm/damon: support ARM32 with LPAE" from SeongJae Park teaches DAMON to understand arm32 highmem - "tools: testing: Use existing atomic.h for vma/maple tests" from Brendan Jackman performs some code cleanups and deduplication under tools/testing/ - "maple_tree: Fix testing for 32bit compiles" from Liam Howlett fixes a couple of 32-bit issues in tools/testing/radix-tree.c - "kasan: unify kasan_enabled() and remove arch-specific implementations" from Sabyrzhan Tasbolatov moves KASAN arch-specific initialization code into a common arch-neutral implementation - "mm: remove zpool" from Johannes Weiner removes zspool - an indirection layer which now only redirects to a single thing (zsmalloc) - "mm: task_stack: Stack handling cleanups" from Pasha Tatashin makes a couple of cleanups in the fork code - "mm: remove nth_page()" from David Hildenbrand makes rather a lot of adjustments at various nth_page() callsites, eventually permitting the removal of that undesirable helper function - "introduce kasan.write_only option in hw-tags" from Yeoreum Yun creates a KASAN read-only mode for ARM, using that architecture's memory tagging feature. It is felt that a read-only mode KASAN is suitable for use in production systems rather than debug-only - "mm: hugetlb: cleanup hugetlb folio allocation" from Kefeng Wang does some tidying in the hugetlb folio allocation code - "mm: establish const-correctness for pointer parameters" from Max Kellermann makes quite a number of the MM API functions more accurate about the constness of their arguments. This was getting in the way of subsystems (in this case CEPH) when they attempt to improving their own const/non-const accuracy - "Cleanup free_pages() misuse" from Vishal Moola fixes a number of code sites which were confused over when to use free_pages() vs __free_pages() - "Add Rust abstraction for Maple Trees" from Alice Ryhl makes the mapletree code accessible to Rust. Required by nouveau and by its forthcoming successor: the new Rust Nova driver - "selftests/mm: split_huge_page_test: split_pte_mapped_thp improvements" from David Hildenbrand adds a fix and some cleanups to the thp selftesting code - "mm, swap: introduce swap table as swap cache (phase I)" from Chris Li and Kairui Song is the first step along the path to implementing "swap tables" - a new approach to swap allocation and state tracking which is expected to yield speed and space improvements. This patchset itself yields a 5-20% performance benefit in some situations - "Some ptdesc cleanups" from Matthew Wilcox utilizes the new memdesc layer to clean up the ptdesc code a little - "Fix va_high_addr_switch.sh test failure" from Chunyu Hu fixes some issues in our 5-level pagetable selftesting code - "Minor fixes for memory allocation profiling" from Suren Baghdasaryan addresses a couple of minor issues in relatively new memory allocation profiling feature - "Small cleanups" from Matthew Wilcox has a few cleanups in preparation for more memdesc work - "mm/damon: add addr_unit for DAMON_LRU_SORT and DAMON_RECLAIM" from Quanmin Yan makes some changes to DAMON in furtherance of supporting arm highmem - "selftests/mm: Add -Wunreachable-code and fix warnings" from Muhammad Anjum adds that compiler check to selftests code and fixes the fallout, by removing dead code - "Improvements to Victim Process Thawing and OOM Reaper Traversal Order" from zhongjinji makes a number of improvements in the OOM killer: mainly thawing a more appropriate group of victim threads so they can release resources - "mm/damon: misc fixups and improvements for 6.18" from SeongJae Park is a bunch of small and unrelated fixups for DAMON - "mm/damon: define and use DAMON initialization check function" from SeongJae Park implement reliability and maintainability improvements to a recently-added bug fix - "mm/damon/stat: expose auto-tuned intervals and non-idle ages" from SeongJae Park provides additional transparency to userspace clients of the DAMON_STAT information - "Expand scope of khugepaged anonymous collapse" from Dev Jain removes some constraints on khubepaged's collapsing of anon VMAs. It also increases the success rate of MADV_COLLAPSE against an anon vma - "mm: do not assume file == vma->vm_file in compat_vma_mmap_prepare()" from Lorenzo Stoakes moves us further towards removal of file_operations.mmap(). This patchset concentrates upon clearing up the treatment of stacked filesystems - "mm: Improve mlock tracking for large folios" from Kiryl Shutsemau provides some fixes and improvements to mlock's tracking of large folios. /proc/meminfo's "Mlocked" field became more accurate - "mm/ksm: Fix incorrect accounting of KSM counters during fork" from Donet Tom fixes several user-visible KSM stats inaccuracies across forks and adds selftest code to verify these counters - "mm_slot: fix the usage of mm_slot_entry" from Wei Yang addresses some potential but presently benign issues in KSM's mm_slot handling * tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (372 commits) mm: swap: check for stable address space before operating on the VMA mm: convert folio_page() back to a macro mm/khugepaged: use start_addr/addr for improved readability hugetlbfs: skip VMAs without shareable locks in hugetlb_vmdelete_list alloc_tag: fix boot failure due to NULL pointer dereference mm: silence data-race in update_hiwater_rss mm/memory-failure: don't select MEMORY_ISOLATION mm/khugepaged: remove definition of struct khugepaged_mm_slot mm/ksm: get mm_slot by mm_slot_entry() when slot is !NULL hugetlb: increase number of reserving hugepages via cmdline selftests/mm: add fork inheritance test for ksm_merging_pages counter mm/ksm: fix incorrect KSM counter handling in mm_struct during fork drivers/base/node: fix double free in register_one_node() mm: remove PMD alignment constraint in execmem_vmalloc() mm/memory_hotplug: fix typo 'esecially' -> 'especially' mm/rmap: improve mlock tracking for large folios mm/filemap: map entire large folio faultaround mm/fault: try to map the entire file folio in finish_fault() mm/rmap: mlock large folios in try_to_unmap_one() mm/rmap: fix a mlock race condition in folio_referenced_one() ...

s390: Remove superfluous newlines from inline assemblies

2025-09-29T11:52:08+00:00

Remove superfluous newlines from inline assemblies. Compilers use the number of lines of inline assemblies as heuristic for the complexity and inline decisions. Therefore inline assemblies should only contain as many lines as required. A lot of inline assemblies contain a superfluous newline for the last line. Remove such newlines to improve compiler inlining decisions. Suggested-by: Juergen Christ Signed-off-by: Heiko Carstens Reviewed-by: Alexander Gordeev Reviewed-by: Juergen Christ Signed-off-by: Alexander Gordeev

s390/mm: Add memory allocation profiling hooks

2025-09-25T12:28:58+00:00

Similar to common code changes [1] add alloc_hook() wrappers to page table allocation functions to allow for memory allocation profiling. If CONFIG_MEM_ALLOC_PROFILING is enabled call sites of page table allocations are accounted, instead of e.g. only crst_table_alloc() and page_table_alloc(). This allows for slightly better profiling data, and the output of /proc/allocinfo is similar to other architectures. Without alloc_hook() wrappers the output of /proc/allocinfo looks like this: 17096704 4174 mm/memory.c:1061 func:folio_prealloc 17809408 4348 mm/memory.c:1063 func:folio_prealloc 0 0 mm/memory.c:4422 func:alloc_swap_folio 0 0 mm/memory.c:4286 func:__alloc_swap_folio 0 0 mm/memory.c:4971 func:alloc_anon_folio ... 1589248 97 arch/s390/mm/pgalloc.c:25 func:crst_table_alloc 0 0 arch/s390/mm/pgalloc.c:124 func:page_table_alloc_pgste 4280320 1045 arch/s390/mm/pgalloc.c:149 func:page_table_alloc With alloc_hook() wrappers: 1097728 268 mm/memory.c:5147 func:__do_fault 20119552 4912 mm/memory.c:1061 func:folio_prealloc 17534976 4281 mm/memory.c:1063 func:folio_prealloc 0 0 mm/memory.c:4422 func:alloc_swap_folio 0 0 mm/memory.c:4286 func:__alloc_swap_folio 786432 192 mm/memory.c:452 func:__pte_alloc 405504 99 mm/memory.c:464 func:__pte_alloc_kernel 1880064 459 mm/memory.c:5525 func:do_fault_around 0 0 mm/memory.c:6403 func:__p4d_alloc 0 0 mm/memory.c:6426 func:__pud_alloc 1064960 65 mm/memory.c:6450 func:__pmd_alloc 0 0 mm/memory.c:4971 func:alloc_anon_folio 0 0 mm/memory.c:5233 func:do_set_pmd [1] commit 2c321f3f70bc ("mm: change inlined allocation helpers to account at the call site") Signed-off-by: Heiko Carstens Acked-by: Alexander Gordeev Signed-off-by: Alexander Gordeev

s390/mm: Use __GFP_ACCOUNT for user page table allocations

2025-09-24T14:24:17+00:00

Add missing kmemcg accounting of user page table allocations. Reviewed-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev

ptdesc: remove ptdesc_to_virt()

2025-09-21T21:22:27+00:00

This has the same effect as ptdesc_address() so convert the callers to use that and delete the function. Add kernel-doc for ptdesc_address(). Link: https://lkml.kernel.org/r/20250908171104.2409217-4-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Acked-by: David Hildenbrand Cc: Vishal Moola (Oracle) Signed-off-by: Andrew Morton