On a 64-bit system, madvise(MADV_DONTNEED) may cause a large number of
empty PTE page table pages (such as 100GB+).  To resolve this problem,
first enable MMU_GATHER_RCU_TABLE_FREE to prepare for enabling the
PT_RECLAIM feature, which resolves this problem.

Link: https://lkml.kernel.org/r/e2217546504668b8a87a39eb0e378839339a1bb4.1769515122.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

um doesn't support KASAN_INLINE together with STATIC_LINK.

Instead of failing the build, disable KASAN_INLINE when
STATIC_LINK is selected.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511290451.x9GZVJ1l-lkp@intel.com/
Fixes: 1e338f4d99e6 ("kasan: introduce ARCH_DEFER_KASAN and unify static key across modes")
Signed-off-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Link: https://patch.msgid.link/2620ab0bbba640b6237c50b9c0dca1c7d1142f5d.1764410067.git.chleroy@kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Add initial symmetric multi-processing (SMP) support to UML. With
this support enabled, users can tell UML to start multiple virtual
processors, each represented as a separate host thread.

In UML, kthreads and normal threads (when running in kernel mode)
can be scheduled and executed simultaneously on different virtual
processors. However, the userspace code of normal threads still
runs within their respective single-threaded stubs.

That is, SMP support is currently available both within the kernel
and across different processes, but still remains limited within
threads of the same process in userspace.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20251027001815.1666872-6-tiwei.bie@linux.dev
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

The file-based iomem emulation was introduced to support writing
paravirtualized drivers based on emulated iomem regions. However,
the only driver that makes use of it is an example driver called
mmapper, which was written over two decades ago.

We now have several modern device emulation mechanisms, such as
vhost-user-based virtio-uml. Remove the file-based iomem emulation
support to reduce the maintenance burden.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20251027054519.1996090-5-tiwei.bie@linux.dev
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Pull uml updates from Johannes Berg:

 - minor preparations for SMP support

 - SPARSE_IRQ support for kunit

 - help output cleanups

* tag 'uml-for-linux-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux:
  um: Remove unused ipi_pipe field from cpuinfo_um
  um: Remove unused cpu_data and current_cpu_data macros
  um: Stop tracking virtual CPUs via mm_cpumask()
  um: Centralize stub size calculations
  um: Remove outdated comment about STUB_DATA_PAGES
  um: Remove unused offset and child_err fields from stub_data
  um: Indent time-travel help messages
  um: Fix help message for ssl-non-raw
  um: vector: Fix indentation for help message
  um: Add missing trailing newline to help messages
  um: virtio-pci: implement .shutdown()
  um: Support SPARSE_IRQ

Patch series "kasan: unify kasan_enabled() and remove arch-specific
implementations", v6.

This patch series addresses the fragmentation in KASAN initialization
across architectures by introducing a unified approach that eliminates
duplicate static keys and arch-specific kasan_arch_is_ready()
implementations.

The core issue is that different architectures have inconsistent approaches
to KASAN readiness tracking:
- PowerPC, LoongArch, and UML arch, each implement own kasan_arch_is_ready()
- Only HW_TAGS mode had a unified static key (kasan_flag_enabled)
- Generic and SW_TAGS modes relied on arch-specific solutions
  or always-on behavior


This patch (of 2):

Introduce CONFIG_ARCH_DEFER_KASAN to identify architectures [1] that need
to defer KASAN initialization until shadow memory is properly set up, and
unify the static key infrastructure across all KASAN modes.

[1] PowerPC, UML, LoongArch selects ARCH_DEFER_KASAN.

The core issue is that different architectures haveinconsistent approaches
to KASAN readiness tracking:
- PowerPC, LoongArch, and UML arch, each implement own
  kasan_arch_is_ready()
- Only HW_TAGS mode had a unified static key (kasan_flag_enabled)
- Generic and SW_TAGS modes relied on arch-specific solutions or always-on
    behavior

This patch addresses the fragmentation in KASAN initialization across
architectures by introducing a unified approach that eliminates duplicate
static keys and arch-specific kasan_arch_is_ready() implementations.

Let's replace kasan_arch_is_ready() with existing kasan_enabled() check,
which examines the static key being enabled if arch selects
ARCH_DEFER_KASAN or has HW_TAGS mode support.  For other arch,
kasan_enabled() checks the enablement during compile time.

Now KASAN users can use a single kasan_enabled() check everywhere.

Link: https://lkml.kernel.org/r/20250810125746.1105476-1-snovitoll@gmail.com
Link: https://lkml.kernel.org/r/20250810125746.1105476-2-snovitoll@gmail.com
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217049
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> #powerpc
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: David Gow <davidgow@google.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huacai Chen <chenhuacai@loongson.cn>
Cc: Marco Elver <elver@google.com>
Cc: Qing Zhang <zhangqing@loongson.cn>
Cc: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Motivation: IRQ KUnit tests are going to require CONFIG_SPARSE_IRQ [1] in
order to:
(a) reliably allocate additional (fake) IRQs and
(b) ensure we can test managed affinity, which is only supported with
    SPARSE_IRQ.

It seems that the only thing necessary for ARCH=um is to tell the genirq
core to skip over our preallocated NR_IRQS.

Tested with:

  $ ./tools/testing/kunit/kunit.py run
  [...]
  [13:55:58] Testing complete. Ran 676 tests: passed: 646, skipped: 30
  [...]

This compares with pre-patch results:

    Ran 672 tests: passed: 644, skipped: 28

i.e., we no longer skip tests that 'depend on SPARSE_IRQ', and existing
tests all pass.

[1]
[PATCH v2 4/6] genirq/test: Depend on SPARSE_IRQ
https://lore.kernel.org/all/CABVgOSngoD0fh1WEkUCEwSdk0Joypo3dA_Y_SjW+K=nVDnZs3Q@mail.gmail.com/

Signed-off-by: Sinan Nalkaya <sardok@gmail.com>
[Brian: Adapted Sinan's patch; rewrote commit message]
Signed-off-by: Brian Norris <briannorris@chromium.org>
Tested-by: David Gow <davidgow@google.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

There is a generic ARCH_HAS_CACHE_LINE_SIZE option introduced by
commit c2280be81de4 ("mm: generalize ARCH_HAS_CACHE_LINE_SIZE")
in mm/Kconfig. Select that instead.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20250708090403.1067440-4-tiwei.bie@linux.dev
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Implement syscall tracepoints through the generic tracing infrastructure.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Nam Cao <namcao@linutronix.de>
Link: https://patch.msgid.link/20250703-uml-have_syscall_tracepoints-v1-2-23c1d3808578@linutronix.de
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

arch/um is one of the last users of CONFIG_GENERIC_IOMAP, but upon
closer look it appears that the PCI host bridge does not register
any port I/O, and the absense of both custom inb/outb functions and
a PCI_IOBASE constant means that actually trying to use port I/O
results on a NULL pointer access.

Build testing with clang confirms this by warning about this exact
problem:

include/asm-generic/io.h:549:31: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic]
  549 |         val = __raw_readb(PCI_IOBASE + addr);
      |                           ~~~~~~~~~~ ^

Remove all the Kconfig selects that refer to legacy port I/O
and instead just build the normal MMIO path that is emulated
by the virtio PCI host.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20250509084125.1488601-1-arnd@kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>