kernel/linux.git/drivers/comedi/comedi_fops.c, branch v7.1-rc5

Merge tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2026-04-15T19:59:16+00:00

Pull MM updates from Andrew Morton: - "maple_tree: Replace big node with maple copy" (Liam Howlett) Mainly prepararatory work for ongoing development but it does reduce stack usage and is an improvement. - "mm, swap: swap table phase III: remove swap_map" (Kairui Song) Offers memory savings by removing the static swap_map. It also yields some CPU savings and implements several cleanups. - "mm: memfd_luo: preserve file seals" (Pratyush Yadav) File seal preservation to LUO's memfd code - "mm: zswap: add per-memcg stat for incompressible pages" (Jiayuan Chen) Additional userspace stats reportng to zswap - "arch, mm: consolidate empty_zero_page" (Mike Rapoport) Some cleanups for our handling of ZERO_PAGE() and zero_pfn - "mm/kmemleak: Improve scan_should_stop() implementation" (Zhongqiu Han) A robustness improvement and some cleanups in the kmemleak code - "Improve khugepaged scan logic" (Vernon Yang) Improve khugepaged scan logic and reduce CPU consumption by prioritizing scanning tasks that access memory frequently - "Make KHO Stateless" (Jason Miu) Simplify Kexec Handover by transitioning KHO from an xarray-based metadata tracking system with serialization to a radix tree data structure that can be passed directly to the next kernel - "mm: vmscan: add PID and cgroup ID to vmscan tracepoints" (Thomas Ballasi and Steven Rostedt) Enhance vmscan's tracepointing - "mm: arch/shstk: Common shadow stack mapping helper and VM_NOHUGEPAGE" (Catalin Marinas) Cleanup for the shadow stack code: remove per-arch code in favour of a generic implementation - "Fix KASAN support for KHO restored vmalloc regions" (Pasha Tatashin) Fix a WARN() which can be emitted the KHO restores a vmalloc area - "mm: Remove stray references to pagevec" (Tal Zussman) Several cleanups, mainly udpating references to "struct pagevec", which became folio_batch three years ago - "mm: Eliminate fake head pages from vmemmap optimization" (Kiryl Shutsemau) Simplify the HugeTLB vmemmap optimization (HVO) by changing how tail pages encode their relationship to the head page - "mm/damon/core: improve DAMOS quota efficiency for core layer filters" (SeongJae Park) Improve two problematic behaviors of DAMOS that makes it less efficient when core layer filters are used - "mm/damon: strictly respect min_nr_regions" (SeongJae Park) Improve DAMON usability by extending the treatment of the min_nr_regions user-settable parameter - "mm/page_alloc: pcp locking cleanup" (Vlastimil Babka) The proper fix for a previously hotfixed SMP=n issue. Code simplifications and cleanups ensued - "mm: cleanups around unmapping / zapping" (David Hildenbrand) A bunch of cleanups around unmapping and zapping. Mostly simplifications, code movements, documentation and renaming of zapping functions - "support batched checking of the young flag for MGLRU" (Baolin Wang) Batched checking of the young flag for MGLRU. It's part cleanups; one benchmark shows large performance benefits for arm64 - "memcg: obj stock and slab stat caching cleanups" (Johannes Weiner) memcg cleanup and robustness improvements - "Allow order zero pages in page reporting" (Yuvraj Sakshith) Enhance free page reporting - it is presently and undesirably order-0 pages when reporting free memory. - "mm: vma flag tweaks" (Lorenzo Stoakes) Cleanup work following from the recent conversion of the VMA flags to a bitmap - "mm/damon: add optional debugging-purpose sanity checks" (SeongJae Park) Add some more developer-facing debug checks into DAMON core - "mm/damon: test and document power-of-2 min_region_sz requirement" (SeongJae Park) An additional DAMON kunit test and makes some adjustments to the addr_unit parameter handling - "mm/damon/core: make passed_sample_intervals comparisons overflow-safe" (SeongJae Park) Fix a hard-to-hit time overflow issue in DAMON core - "mm/damon: improve/fixup/update ratio calculation, test and documentation" (SeongJae Park) A batch of misc/minor improvements and fixups for DAMON - "mm: move vma_(kernel|mmu)_pagesize() out of hugetlb.c" (David Hildenbrand) Fix a possible issue with dax-device when CONFIG_HUGETLB=n. Some code movement was required. - "zram: recompression cleanups and tweaks" (Sergey Senozhatsky) A somewhat random mix of fixups, recompression cleanups and improvements in the zram code - "mm/damon: support multiple goal-based quota tuning algorithms" (SeongJae Park) Extend DAMOS quotas goal auto-tuning to support multiple tuning algorithms that users can select - "mm: thp: reduce unnecessary start_stop_khugepaged()" (Breno Leitao) Fix the khugpaged sysfs handling so we no longer spam the logs with reams of junk when starting/stopping khugepaged - "mm: improve map count checks" (Lorenzo Stoakes) Provide some cleanups and slight fixes in the mremap, mmap and vma code - "mm/damon: support addr_unit on default monitoring targets for modules" (SeongJae Park) Extend the use of DAMON core's addr_unit tunable - "mm: khugepaged cleanups and mTHP prerequisites" (Nico Pache) Cleanups to khugepaged and is a base for Nico's planned khugepaged mTHP support - "mm: memory hot(un)plug and SPARSEMEM cleanups" (David Hildenbrand) Code movement and cleanups in the memhotplug and sparsemem code - "mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE and cleanup CONFIG_MIGRATION" (David Hildenbrand) Rationalize some memhotplug Kconfig support - "change young flag check functions to return bool" (Baolin Wang) Cleanups to change all young flag check functions to return bool - "mm/damon/sysfs: fix memory leak and NULL dereference issues" (Josh Law and SeongJae Park) Fix a few potential DAMON bugs - "mm/vma: convert vm_flags_t to vma_flags_t in vma code" (Lorenzo Stoakes) Convert a lot of the existing use of the legacy vm_flags_t data type to the new vma_flags_t type which replaces it. Mainly in the vma code. - "mm: expand mmap_prepare functionality and usage" (Lorenzo Stoakes) Expand the mmap_prepare functionality, which is intended to replace the deprecated f_op->mmap hook which has been the source of bugs and security issues for some time. Cleanups, documentation, extension of mmap_prepare into filesystem drivers - "mm/huge_memory: refactor zap_huge_pmd()" (Lorenzo Stoakes) Simplify and clean up zap_huge_pmd(). Additional cleanups around vm_normal_folio_pmd() and the softleaf functionality are performed. * tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits) mm: fix deferred split queue races during migration mm/khugepaged: fix issue with tracking lock mm/huge_memory: add and use has_deposited_pgtable() mm/huge_memory: add and use normal_or_softleaf_folio_pmd() mm: add softleaf_is_valid_pmd_entry(), pmd_to_softleaf_folio() mm/huge_memory: separate out the folio part of zap_huge_pmd() mm/huge_memory: use mm instead of tlb->mm mm/huge_memory: remove unnecessary sanity checks mm/huge_memory: deduplicate zap deposited table call mm/huge_memory: remove unnecessary VM_BUG_ON_PAGE() mm/huge_memory: add a common exit path to zap_huge_pmd() mm/huge_memory: handle buggy PMD entry in zap_huge_pmd() mm/huge_memory: have zap_huge_pmd return a boolean, add kdoc mm/huge: avoid big else branch in zap_huge_pmd() mm/huge_memory: simplify vma_is_specal_huge() mm: on remap assert that input range within the proposed VMA mm: add mmap_action_map_kernel_pages[_full]() uio: replace deprecated mmap hook with mmap_prepare in uio_info drivers: hv: vmbus: replace deprecated mmap hook with mmap_prepare mm: allow handling of stacked mmap_prepare hooks in more drivers ...

mm: rename zap_vma_ptes() to zap_special_vma_range()

2026-04-05T20:53:15+00:00

zap_vma_ptes() is the only zapping function we export to modules. It's essentially a wrapper around zap_vma_range(), however, with some safety checks: * That the passed range fits fully into the VMA * That it's only used for VM_PFNMAP We will add support for VM_MIXEDMAP next, so use the more-generic term "special vma", although "special" is a bit overloaded. Maybe we'll later just support any VM_SPECIAL flag. While at it, improve the kerneldoc. Link: https://lkml.kernel.org/r/20260227200848.114019-16-david@kernel.org Signed-off-by: David Hildenbrand (Arm) Acked-by: Leon Romanovsky [drivers/infiniband] Reviewed-by: Lorenzo Stoakes (Oracle) Cc: Alexander Gordeev Cc: Alexei Starovoitov Cc: Alice Ryhl Cc: Andrii Nakryiko Cc: Andy Lutomirski Cc: Arnaldo Carvalho de Melo Cc: Arnd Bergmann Cc: Arve Cc: "Borislav Petkov (AMD)" Cc: Carlos Llamas Cc: Christian Borntraeger Cc: Christian Brauner Cc: Claudio Imbrenda Cc: Daniel Borkman Cc: Dave Airlie Cc: David Ahern Cc: David Rientjes Cc: David S. Miller Cc: Dimitri Sivanich Cc: Eric Dumazet Cc: Gerald Schaefer Cc: Greg Kroah-Hartman Cc: Hartley Sweeten Cc: Heiko Carstens Cc: Ian Abbott Cc: Ingo Molnar Cc: Jakub Kacinski Cc: Jani Nikula Cc: Jann Horn Cc: Janosch Frank Cc: Jarkko Sakkinen Cc: Jason Gunthorpe Cc: Jonas Lahtinen Cc: Liam Howlett Cc: Madhavan Srinivasan Cc: Matthew Wilcox (Oracle) Cc: Michael Ellerman Cc: Michal Hocko Cc: Miguel Ojeda Cc: Mike Rapoport Cc: Namhyung kim Cc: Neal Cardwell Cc: Paolo Abeni Cc: Pedro Falcato Cc: Peter Zijlstra Cc: Rodrigo Vivi Cc: Shakeel Butt Cc: Suren Baghdasaryan Cc: Todd Kjos Cc: Tvrtko Ursulin Cc: Vasily Gorbik Cc: Vincenzo Frascino Signed-off-by: Andrew Morton

comedi: runflags cannot determine whether to reclaim chanlist

2026-04-02T12:39:58+00:00

syzbot reported a memory leak [1], because commit 4e1da516debb ("comedi: Add reference counting for Comedi command handling") did not consider the exceptional exit case in do_cmd_ioctl() where runflags is not set. This caused chanlist not to be properly freed by do_become_nonbusy(), as it only frees chanlist when runflags is correctly set. Added a check in do_become_nonbusy() for the case where runflags is not set, to properly free the chanlist memory. [1] BUG: memory leak backtrace (crc 844a0efa): __comedi_get_user_chanlist drivers/comedi/comedi_fops.c:1815 [inline] do_cmd_ioctl.part.0+0x112/0x350 drivers/comedi/comedi_fops.c:1890 do_cmd_ioctl drivers/comedi/comedi_fops.c:1858 [inline] Fixes: 4e1da516debb ("comedi: Add reference counting for Comedi command handling") Reported-by: syzbot+f238baf6ded841b5a82e@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f238baf6ded841b5a82e Signed-off-by: Edward Adam Davis Reviewed-by: Ian Abbott Cc: stable # 6.19 Signed-off-by: Ian Abbott Link: https://patch.msgid.link/20260310111104.70959-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

Merge 6.19-rc7 into char-misc-next

2026-01-26T11:04:04+00:00

We need the char/misc/iio fixes in here as well. Signed-off-by: Greg Kroah-Hartman

comedi: Fix getting range information for subdevices 16 to 255

2026-01-16T15:42:15+00:00

The `COMEDI_RANGEINFO` ioctl does not work properly for subdevice indices above 15. Currently, the only in-tree COMEDI drivers that support more than 16 subdevices are the "8255" driver and the "comedi_bond" driver. Making the ioctl work for subdevice indices up to 255 is achievable. It needs minor changes to the handling of the `COMEDI_RANGEINFO` and `COMEDI_CHANINFO` ioctls that should be mostly harmless to user-space, apart from making them less broken. Details follow... The `COMEDI_RANGEINFO` ioctl command gets the list of supported ranges (usually with units of volts or milliamps) for a COMEDI subdevice or channel. (Only some subdevices have per-channel range tables, indicated by the `SDF_RANGETYPE` flag in the subdevice information.) It uses a `range_type` value and a user-space pointer, both supplied by user-space, but the `range_type` value should match what was obtained using the `COMEDI_CHANINFO` ioctl (if the subdevice has per-channel range tables) or `COMEDI_SUBDINFO` ioctl (if the subdevice uses a single range table for all channels). Bits 15 to 0 of the `range_type` value contain the length of the range table, which is the only part that user-space should care about (so it can use a suitably sized buffer to fetch the range table). Bits 23 to 16 store the channel index, which is assumed to be no more than 255 if the subdevice has per-channel range tables, and is set to 0 if the subdevice has a single range table. For `range_type` values produced by the `COMEDI_SUBDINFO` ioctl, bits 31 to 24 contain the subdevice index, which is assumed to be no more than 255. But for `range_type` values produced by the `COMEDI_CHANINFO` ioctl, bits 27 to 24 contain the subdevice index, which is assumed to be no more than 15, and bits 31 to 28 contain the COMEDI device's minor device number for some unknown reason lost in the mists of time. The `COMEDI_RANGEINFO` ioctl extract the length from bits 15 to 0 of the user-supplied `range_type` value, extracts the channel index from bits 23 to 16 (only used if the subdevice has per-channel range tables), extracts the subdevice index from bits 27 to 24, and ignores bits 31 to 28. So for subdevice indices 16 to 255, the `COMEDI_SUBDINFO` or `COMEDI_CHANINFO` ioctl will report a `range_type` value that doesn't work with the `COMEDI_RANGEINFO` ioctl. It will either get the range table for the subdevice index modulo 16, or will fail with `-EINVAL`. To fix this, always use bits 31 to 24 of the `range_type` value to hold the subdevice index (assumed to be no more than 255). This affects the `COMEDI_CHANINFO` and `COMEDI_RANGEINFO` ioctls. There should not be anything in user-space that depends on the old, broken usage, although it may now see different values in bits 31 to 28 of the `range_type` values reported by the `COMEDI_CHANINFO` ioctl for subdevices that have per-channel subdevices. User-space should not be trying to decode bits 31 to 16 of the `range_type` values anyway. Fixes: ed9eccbe8970 ("Staging: add comedi core") Cc: stable@vger.kernel.org #5.17+ Signed-off-by: Ian Abbott Link: https://patch.msgid.link/20251203162438.176841-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman

comedi: don't use mutex for COMEDI_BUFINFO ioctl

2026-01-16T15:33:08+00:00

The main mutex in a comedi device can get held for quite a while when processing comedi instructions, so for performance reasons, the "read", "write", and "poll" file operations do not use it; they use the `attach_lock` rwsemaphore to protect against the comedi device becoming detached at an inopportune moment. As an alternative to using the "read" and "write" operations, user-space can mmap the data buffer and use the `COMEDI_BUFINFO` ioctl to manage data transfer through the buffer. However, the "ioctl" file handler currently locks the main mutex for all ioctl commands. Make the handling of the `COMEDI_BUFINFO` an exception, using the `attach_lock` rwsemaphore during normal operation. However, before it calls `do_become_nonbusy()` at the end of acquisition, it does need to lock the main mutex, but it needs to unlock the `attach_lock` rwsemaphore first to avoid deadlock. After locking the main mutex, it needs to check that it is still in a suitable state to become non-busy, because things may have changed while unlocked. Signed-off-by: Ian Abbott Link: https://patch.msgid.link/20251205131332.16672-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman

comedi: Use reference count for asynchronous command functions

2025-11-26T13:19:41+00:00

comedi: Add reference counting for Comedi command handling

2025-11-26T13:19:41+00:00

For interrupts from badly behaved hardware (as emulated by Syzbot), it is possible for the Comedi core functions that manage the progress of asynchronous data acquisition to be called from driver ISRs while no asynchronous command has been set up, which can cause problems such as invalid pointer dereferencing or dividing by zero. To help protect against that, introduce new functions to maintain a reference counter for asynchronous commands that are being set up. `comedi_get_is_subdevice_running(s)` will check if a command has been set up on a subdevice and is still marked as running, and if so will increment the reference counter and return `true`, otherwise it will return `false` without modifying the reference counter. `comedi_put_is_subdevice_running(s)` will decrement the reference counter and set a completion event when decremented to 0. Change the `do_cmd_ioctl()` function (responsible for setting up the asynchronous command) to reinitialize the completion event and set the reference counter to 1 before it marks the subdevice as running. Change the `do_become_nonbusy()` function (responsible for destroying a completed command) to call `comedi_put_is_subdevice_running(s)` and wait for the completion event after marking the subdevice as not running. Because the subdevice normally gets marked as not running before the call to `do_become_nonbusy()` (and may also be called when the Comedi device is being detached from the low-level driver), add a new flag `COMEDI_SRF_BUSY` to the set of subdevice run-flags that indicates that an asynchronous command was set up and will need to be destroyed. This flag is set by `do_cmd_ioctl()` and cleared and checked by `do_become_nonbusy()`. Subsequent patches will change the Comedi core functions that are called from low-level drivers for asynchrous command handling to make use of the `comedi_get_is_subdevice_running()` and `comedi_put_is_subdevice_running()` functions, and will modify the ISRs of some of these low-level drivers if they dereference the subdevice's `async` pointer directly. Signed-off-by: Ian Abbott Link: https://patch.msgid.link/20251023133001.8439-2-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman