kernel/git/next/linux-next.git/arch/um, branch master

Merge branch 'linux-next' of https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git

2026-09-11T15:00:56+00:00

Merge branch 'mm-nonmm-unstable' of https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2026-09-11T12:03:59+00:00

init, arch: make CONFIG_COMMAND_LINE_SIZE globally configurable

2026-09-11T03:22:07+00:00

Currently, s390 has the ability to configure the maximum kernel command line size via Kconfig (CONFIG_COMMAND_LINE_SIZE). Other architectures define a hardcoded COMMAND_LINE_SIZE macro in their setup.h headers. In some use cases, such as netboot kernels, rootfs configurations, or larger initramfs setups, a larger command line size is required. While for embedded workloads, it can be reduced to save memory. Move CONFIG_COMMAND_LINE_SIZE out of arch/s390/Kconfig and into init/Kconfig under General setup, and update every architecture's setup.h header to define COMMAND_LINE_SIZE as CONFIG_COMMAND_LINE_SIZE. For user-space API (uapi) headers, wrap the definition in an `#ifdef __KERNEL__` guard and retain the historical hardcoded default in the `#else` block. When user-space headers are installed via `make headers_install`, unifdef strips out the kernel section, ensuring the same value as before for user-space applications including ``. For S390, the range is kept the same, but other architectures have varying constraints. S390 requires a minimum of 896 bytes to protect legacy bootloaders from overwriting the .text section. ARM, M68K, and NIOS2 allocate the command line directly on severely constrained decompressor stacks, so their ranges are strictly capped at 2048 bytes to prevent deterministic stack exhaustion and boot panics. PowerPC (PPC) boot wrappers silently truncate arguments past 2048 bytes, so it is also capped at 2048 to prevent silent parameter loss. The SuperH (SUPERH) boot parameter page allocates exactly PAGE_SIZE (typically 4096 bytes), and placing a 4096-byte command line starting at offset 256 would cause strscpy() to read out of bounds; it is capped at 3840 bytes. Alpha physically limits its boot parameter block to 256 bytes, so its limit is strictly locked to 256. All other architectures are capped at 4096 bytes to prevent unreasonable allocations. Link: https://lore.kernel.org/20260818231646.804507-2-wfelipe@google.com Signed-off-by: Maciej Żenczykowski Signed-off-by: Wilson Felipe Pereira Cc: Albert Ou Cc: Alexander Gordeev Cc: Alexandre Ghiti Cc: Arnd Bergmann Cc: Christian Borntraeger Cc: Heiko Carstens Cc: Palmer Dabbelt Cc: Sven Schnelle Cc: Vasily Gorbik Signed-off-by: Andrew Morton

mm: make userland page table freeing RCU-safe

2026-09-11T03:21:19+00:00

Now every architecture has been converted to support CONFIG_MMU_GATHER_RCU_TABLE_FREE, this configuration option no longer makes any sense to keep around. Therefore remove it, and remove all the dead code that existed for !CONFIG_MMU_GATHER_RCU_TABLE_FREE architectures previously. Additionally, CONFIG_MMU_GATHER_TABLE_FREE is no longer necessary, as all architectures instead use CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE when a custom __tlb_remove_table() is required, so remove this too. A number of architectures only enabled CONFIG_MMU_GATHER_RCU_TABLE_FREE if CONFIG_MMU was set, however the mmu_gather logic only actually does something meaningful if CONFIG_MMU is set (mmu_gather.c is only compiled in this case, for instance). As a result, there's no need to gate any of this logic on CONFIG_MMU explicitly. CONFIG_PT_RECLAIM however does have a strict dependency on CONFIG_MMU, so make this dependency explicit. Additionally, correct comments to remove references to non-RCU page table gathering and make it clear that this is not 'semi-RCU', nor has it been since commit 1fb3d8c20bfa ("mm/mmu_gather: replace IPI with synchronize_rcu() when batch allocation fails"). With this change in place the kernel policy is now that all page tables are freed after an RCU grace period, and thus it is now safe to unconditionally perform page table walks under RCU, safe in the knowledge that page tables will not be freed underneath the walker. This is all that is guaranteed, however, so naturally it is still incumbent upon page table walkers to ensure that the page table entries are as expected. Link: https://lore.kernel.org/20260908-rcu-pagetable-freeing-v2-11-1f60b64e878e@kernel.org Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: Kiryl Shutsemau (Meta) Cc: Albert Ou Cc: Alexander Gordeev Cc: Alexandre Ghiti Cc: Andreas Larsson Cc: "Aneesh Kumar K.V" Cc: Anton Ivanov Cc: Arnd Bergmann Cc: Baolin Wang Cc: Barry Song Cc: "Borislav Petkov (AMD)" Cc: Catalin Marinas Cc: Christian Borntraeger Cc: Christian Zankel Cc: Dave Hansen Cc: David Hildenbrand Cc: David S. Miller Cc: Dev Jain Cc: Dinh Nguyen Cc: Geert Uytterhoeven Cc: Guo Ren Cc: Heiko Carstens Cc: Helge Deller Cc: "H. Peter Anvin" Cc: Huacai Chen Cc: Hugh Dickins Cc: Ingo Molnar Cc: James Bottomley Cc: Jason Gunthorpe Cc: Johannes Berg Cc: John Hubbard Cc: John Paul Adrian Glaubitz Cc: Jonas Bonn Cc: Lance Yang Cc: Liam R. Howlett Cc: Madhavan Srinivasan Cc: Magnus Lindholm Cc: Marc Rutland Cc: Matt Turner Cc: Max Filippov Cc: Michael Ellerman Cc: Michal Hocko Cc: Michal Simek Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Palmer Dabbelt Cc: Peter Xu Cc: Peter Zijlstra Cc: Richard Henderson Cc: Richard Weinberger Cc: Rich Felker Cc: Russell King Cc: Ryan Roberts Cc: Stafford Horne Cc: Stefan Kristiansson Cc: Suren Baghdasaryan Cc: Sven Schnelle Cc: Thomas Bogendoerfer Cc: Vasily Gorbik Cc: Vineet Gupta Cc: Vlastimil Babka Cc: WANG Xuerui Cc: Will Deacon Cc: Yoshinori Sato Cc: Zi Yan Signed-off-by: Andrew Morton

mm: drop pxd_ERROR()

2026-09-11T03:20:36+00:00

There are no more users left for any pxd_ERROR() either in generic MM or in the platform MM. Hence all these platform macros along with their generic fallback could be dropped across the tree. Link: https://lore.kernel.org/20260831054331.625505-9-anshuman.khandual@arm.com Signed-off-by: Anshuman Khandual Acked-by: Geert Uytterhoeven # m68k Acked-by: David Hildenbrand (Arm) Acked-by: Mike Rapoport (Microsoft) Cc: Helge Deller Cc: Huacai Chen Cc: James Bottomley Cc: John Paul Adrian Glaubitz Cc: Lorenzo Stoakes Cc: Rich Felker Cc: Samuel Holland Cc: WANG Xuerui Cc: Yoshinori Sato Signed-off-by: Andrew Morton

um: virtio_uml: implement synchronize_cbs()

2026-09-08T08:23:49+00:00

virtio_uml invokes virtqueue callbacks from vu_interrupt() and vu_req_interrupt(), which share vu_dev->irq. The core's synchronize_rcu() fallback already covers these IRQ handlers. Implement synchronize_cbs() with synchronize_irq() to synchronize with that IRQ instead of waiting for an RCU grace period. Assisted-by: LLM Signed-off-by: Karl Mehltretter Signed-off-by: Michael S. Tsirkin Message-ID: <20260908053817.26065-5-kmehltretter@gmail.com>

um: Use asm-generic/timex.h over the host architecture one

2026-08-25T00:10:35+00:00

The removal of the architecture-specific asm/timex.h was meant to fall back to asm-generic/timex.h. However on UML, the host architecture headers are earlier on the include path and therefore asm/timex.h from the host architecture is used. On x86 that header in turn requires the generation of cpufeaturemasks.h, which is not set up for UML and the build fails. In file included from ../arch/x86/include/asm/tsc.h:9, from ../arch/x86/include/asm/timex.h:6, from ../include/linux/timex.h:67, from ../include/linux/time32.h:13, from ../include/linux/time.h:60, from ../include/linux/jiffies.h:10, from ../include/linux/ktime.h:25, from ../include/linux/timer.h:6, from ../include/linux/uprobes.h:18, from ../include/linux/mm_types.h:16, from ../include/linux/mmzone.h:22, from ../include/linux/gfp.h:7, from ../include/linux/slab.h:17, from ../include/linux/crypto.h:18, from ../arch/um/kernel/asm-offsets.c:6: arch/x86/include/asm/tsc.h: In function ‘get_cycles’: arch/um/include/asm/cpufeature.h:52:39: error: implicit declaration of function ‘DISABLED_MASK_BIT_SET’ [-Wimplicit-function-declaration] 52 | (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : _static_cpu_has(bit)) | ^~~~~~~~~~~~~~~~~~~~~ arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro ‘cpu_feature_enabled’ 79 | if (!cpu_feature_enabled(X86_FEATURE_TSC)) | ^~~~~~~~~~~~~~~~~~~ arch/um/include/asm/cpufeature.h:115:17: error: implicit declaration of function ‘_static_cpu_has’ [-Wimplicit-function-declaration] 115 | _static_cpu_has(bit) \ | ^~~~~~~~~~~~~~~ ... The x86-specific timex.h also doesn't make sense on UML in general. Reintroduce the UML-specific asm/timex.h and add a comment to document its necessity. [ bp: Improve that comment to actually state why stuff is there. ] Fixes: 3ed403bbc967 ("treewide: Remove CLOCK_TICK_RATE") Signed-off-by: Thomas Weißschuh Signed-off-by: Borislav Petkov (AMD) Reviewed-by: David Gow Link: https://patch.msgid.link/20260819-uml-timex-fix-v1-1-f690b514fc9f@linutronix.de

Merge tag 'x86_cpu_for_v7.3_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-08-19T02:09:42+00:00

Pull x86 cpuid updates from Borislav Petkov: - Get rid of static_cpu_has() - one less API to care about testing CPU features - Unify the handling of CPU core types (performance, efficient, etc) by mapping the vendor-specific types to Linux ones - Continuation of the work of Ahmed Darwish to centralize CPUID leaf representation * tag 'x86_cpu_for_v7.3_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/CPU: Rename struct cpuid_read_output to struct cpuid_output x86/cpu/scattered: Sort it properly x86/cpu: Use parsed CPUID(0x1) x86/lib: Add CPUID(0x1) family and model calculation x86/cpu: Use parsed CPUID(0x0) x86/cpu/transmeta: Rescan CPUID(0x1) after modifying capabilities x86/topology: Add TOPO_CPU_TYPE_LOW_POWER x86/topology: Name the AMD core-type values x86/topo: Map vendor CPU types to generic Linux such types x86/bugs: Don't use cpu-type matching in cpu_vuln_blacklist x86/cpu: Hide and rename static_cpu_has()

Merge tag 'x86_alternatives_for_v7.3_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-08-19T01:11:25+00:00

Pull x86 alternatives update from Borislav Petkov: - Remove the smp_locks alternatives machinery which was used to patch out lock prefixes when running a SMP kernel on a uniprocessor machine * tag 'x86_alternatives_for_v7.3_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/alternative: Drop smp_locks glue

Merge tag 'timers-cleanups-2026-08-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-08-18T22:58:29+00:00

Pull treewide timer related cleanups from Thomas Gleixner: - Remove the leftover CLOCK_TICK_RATE which has been scheduled for removal more than a decade ago along with some now empty asm/timex.h files. - Consolidate delay timer calibration The construct of having a define in a header requires that architectures provided asm/timex.h for no reason. Also the function name for reading the delay timer is confusing at best. Use a config switch to enable that functionality and rename the function to delay_read_timer() to make the purpose clear. This removes some more now empty asm/timex.h files as well. * tag 'timers-cleanups-2026-08-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: calibrate: Rework delay timer calibration treewide: Remove CLOCK_TICK_RATE x86: Use PIT_TICK_RATE instead of CLOCK_TICK_RATE