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Ritesh Harjani (IBM)andMadhavan Srinivasan 07791ff060 powerpc: Print MMU_FTRS_POSSIBLE & MMU_FTRS_ALWAYS at startup 
Similar to CPU_FTRS_[POSSIBLE|ALWAYS], let's also print
MMU_FTRS_[POSSIBLE|ALWAYS]. This has some useful data to capture during
bootup.

Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/c37a9f314a723048d25aa5424f7ede8eec691d86.1773078178.git.ritesh.list@gmail.com
 2026-03-17 13:56:37 +05:30
Ritesh Harjani (IBM)andMadhavan Srinivasan 0a8321dde0 powerpc/mem: Move CMA reservations to arch_mm_preinit 
commit 4267739cab ("arch, mm: consolidate initialization of SPARSE memory model"),
changed the initialization order of "pageblock_order" from...
start_kernel()
    - setup_arch()
       - initmem_init()
         - sparse_init()
           - set_pageblock_order();  // this sets the pageblock_order
       - xxx_cma_reserve();

to...
start_kernel()
    - setup_arch()
       - xxx_cma_reserve();
    - mm_core_init_early()
       - free_area_init()
          - sparse_init()
             - set_pageblock_order() // this sets the pageblock_order.

So this means, pageblock_order is not initialized before these cma
reservation function calls, hence we are seeing CMA failures like...

[    0.000000] kvm_cma_reserve: reserving 3276 MiB for global area
[    0.000000] cma: pageblock_order not yet initialized. Called during early boot?
[    0.000000] cma: Failed to reserve 3276 MiB
....
[    0.000000][    T0] cma: pageblock_order not yet initialized. Called during early boot?
[    0.000000][    T0] cma: Failed to reserve 1024 MiB

This patch moves these CMA reservations to arch_mm_preinit() which
happens in mm_core_init() (which happens after pageblock_order is
initialized), but before the memblock moves the free memory to buddy.

Fixes: 4267739cab ("arch, mm: consolidate initialization of SPARSE memory model")
Suggested-by: Mike Rapoport <rppt@kernel.org>
Reported-and-tested-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Closes: https://lore.kernel.org/linuxppc-dev/4c338a29-d190-44f3-8874-6cfa0a031f0b@linux.ibm.com/
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Tested-by: Dan Horák <dan@danny.cz>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/6e532cf0db5be99afbe20eed699163d5e86cd71f.1772303986.git.ritesh.list@gmail.com
 2026-03-12 10:57:31 +05:30
Mike Rapoport (Microsoft)andAndrew Morton 9fac145b6d mm, arch: consolidate hugetlb CMA reservation 
Every architecture that supports hugetlb_cma command line parameter
reserves CMA areas for hugetlb during setup_arch().

This obfuscates the ordering of hugetlb CMA initialization with respect to
the rest initialization of the core MM.

Introduce arch_hugetlb_cma_order() callback to allow architectures report
the desired order-per-bit of CMA areas and provide a week implementation
of arch_hugetlb_cma_order() for architectures that don't support hugetlb
with CMA.

Use this callback in hugetlb_cma_reserve() instead if passing the order as
parameter and call hugetlb_cma_reserve() from mm_core_init_early() rather
than have it spread over architecture specific code.

Link: https://lkml.kernel.org/r/20260111082105.290734-28-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam 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: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-01-26 20:02:19 -08:00
Sourabh JainandMadhavan Srinivasan b4a96ab50f powerpc/kdump: Add support for crashkernel CMA reservation 
Commit 35c18f2933 ("Add a new optional ",cma" suffix to the
crashkernel= command line option") and commit ab475510e0 ("kdump:
implement reserve_crashkernel_cma") added CMA support for kdump
crashkernel reservation.

Extend crashkernel CMA reservation support to powerpc.

The following changes are made to enable CMA reservation on powerpc:

- Parse and obtain the CMA reservation size along with other crashkernel
  parameters
- Call reserve_crashkernel_cma() to allocate the CMA region for kdump
- Include the CMA-reserved ranges in the usable memory ranges for the
  kdump kernel to use.
- Exclude the CMA-reserved ranges from the crash kernel memory to
  prevent them from being exported through /proc/vmcore.

With the introduction of the CMA crashkernel regions,
crash_exclude_mem_range() needs to be called multiple times to exclude
both crashk_res and crashk_cma_ranges from the crash memory ranges. To
avoid repetitive logic for validating mem_ranges size and handling
reallocation when required, this functionality is moved to a new wrapper
function crash_exclude_mem_range_guarded().

To ensure proper CMA reservation, reserve_crashkernel_cma() is called
after pageblock_order is initialized.

Update kernel-parameters.txt to document CMA support for crashkernel on
powerpc architecture.

Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20251107080334.708028-1-sourabhjain@linux.ibm.com
 2025-11-11 14:11:08 +05:30
Mike Rapoport (Microsoft)andAndrew Morton 8268af309d arch, mm: set max_mapnr when allocating memory map for FLATMEM 
max_mapnr is essentially the size of the memory map for systems that use
FLATMEM. There is no reason to calculate it in each and every architecture
when it's anyway calculated in alloc_node_mem_map().

Drop setting of max_mapnr from architecture code and set it once in
alloc_node_mem_map().

While on it, move definition of mem_map and max_mapnr to mm/mm_init.c so
there won't be two copies for MMU and !MMU variants.

Link: https://lkml.kernel.org/r/20250313135003.836600-10-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>	[x86]
Tested-by: Mark Brown <broonie@kernel.org>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Guo Ren (csky) <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-17 22:06:52 -07:00
Linus Torvalds 9c5968db9e Merge tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 
Pull MM updates from Andrew Morton:
 "The various patchsets are summarized below. Plus of course many
  indivudual patches which are described in their changelogs.

   - "Allocate and free frozen pages" from Matthew Wilcox reorganizes
     the page allocator so we end up with the ability to allocate and
     free zero-refcount pages. So that callers (ie, slab) can avoid a
     refcount inc & dec

   - "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to
     use large folios other than PMD-sized ones

   - "Fix mm/rodata_test" from Petr Tesarik performs some maintenance
     and fixes for this small built-in kernel selftest

   - "mas_anode_descend() related cleanup" from Wei Yang tidies up part
     of the mapletree code

   - "mm: fix format issues and param types" from Keren Sun implements a
     few minor code cleanups

   - "simplify split calculation" from Wei Yang provides a few fixes and
     a test for the mapletree code

   - "mm/vma: make more mmap logic userland testable" from Lorenzo
     Stoakes continues the work of moving vma-related code into the
     (relatively) new mm/vma.c

   - "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David
     Hildenbrand cleans up and rationalizes handling of gfp flags in the
     page allocator

   - "readahead: Reintroduce fix for improper RA window sizing" from Jan
     Kara is a second attempt at fixing a readahead window sizing issue.
     It should reduce the amount of unnecessary reading

   - "synchronously scan and reclaim empty user PTE pages" from Qi Zheng
     addresses an issue where "huge" amounts of pte pagetables are
     accumulated:

       https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/

     Qi's series addresses this windup by synchronously freeing PTE
     memory within the context of madvise(MADV_DONTNEED)

   - "selftest/mm: Remove warnings found by adding compiler flags" from
     Muhammad Usama Anjum fixes some build warnings in the selftests
     code when optional compiler warnings are enabled

   - "mm: don't use __GFP_HARDWALL when migrating remote pages" from
     David Hildenbrand tightens the allocator's observance of
     __GFP_HARDWALL

   - "pkeys kselftests improvements" from Kevin Brodsky implements
     various fixes and cleanups in the MM selftests code, mainly
     pertaining to the pkeys tests

   - "mm/damon: add sample modules" from SeongJae Park enhances DAMON to
     estimate application working set size

   - "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn
     provides some cleanups to memcg's hugetlb charging logic

   - "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song
     removes the global swap cgroup lock. A speedup of 10% for a
     tmpfs-based kernel build was demonstrated

   - "zram: split page type read/write handling" from Sergey Senozhatsky
     has several fixes and cleaups for zram in the area of
     zram_write_page(). A watchdog softlockup warning was eliminated

   - "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin
     Brodsky cleans up the pagetable destructor implementations. A rare
     use-after-free race is fixed

   - "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes
     simplifies and cleans up the debugging code in the VMA merging
     logic

   - "Account page tables at all levels" from Kevin Brodsky cleans up
     and regularizes the pagetable ctor/dtor handling. This results in
     improvements in accounting accuracy

   - "mm/damon: replace most damon_callback usages in sysfs with new
     core functions" from SeongJae Park cleans up and generalizes
     DAMON's sysfs file interface logic

   - "mm/damon: enable page level properties based monitoring" from
     SeongJae Park increases the amount of information which is
     presented in response to DAMOS actions

   - "mm/damon: remove DAMON debugfs interface" from SeongJae Park
     removes DAMON's long-deprecated debugfs interfaces. Thus the
     migration to sysfs is completed

   - "mm/hugetlb: Refactor hugetlb allocation resv accounting" from
     Peter Xu cleans up and generalizes the hugetlb reservation
     accounting

   - "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino
     removes a never-used feature of the alloc_pages_bulk() interface

   - "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park
     extends DAMOS filters to support not only exclusion (rejecting),
     but also inclusion (allowing) behavior

   - "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi
     introduces a new memory descriptor for zswap.zpool that currently
     overlaps with struct page for now. This is part of the effort to
     reduce the size of struct page and to enable dynamic allocation of
     memory descriptors

   - "mm, swap: rework of swap allocator locks" from Kairui Song redoes
     and simplifies the swap allocator locking. A speedup of 400% was
     demonstrated for one workload. As was a 35% reduction for kernel
     build time with swap-on-zram

   - "mm: update mips to use do_mmap(), make mmap_region() internal"
     from Lorenzo Stoakes reworks MIPS's use of mmap_region() so that
     mmap_region() can be made MM-internal

   - "mm/mglru: performance optimizations" from Yu Zhao fixes a few
     MGLRU regressions and otherwise improves MGLRU performance

   - "Docs/mm/damon: add tuning guide and misc updates" from SeongJae
     Park updates DAMON documentation

   - "Cleanup for memfd_create()" from Isaac Manjarres does that thing

   - "mm: hugetlb+THP folio and migration cleanups" from David
     Hildenbrand provides various cleanups in the areas of hugetlb
     folios, THP folios and migration

   - "Uncached buffered IO" from Jens Axboe implements the new
     RWF_DONTCACHE flag which provides synchronous dropbehind for
     pagecache reading and writing. To permite userspace to address
     issues with massive buildup of useless pagecache when
     reading/writing fast devices

   - "selftests/mm: virtual_address_range: Reduce memory" from Thomas
     Weißschuh fixes and optimizes some of the MM selftests"

* tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits)
  mm/compaction: fix UBSAN shift-out-of-bounds warning
  s390/mm: add missing ctor/dtor on page table upgrade
  kasan: sw_tags: use str_on_off() helper in kasan_init_sw_tags()
  tools: add VM_WARN_ON_VMG definition
  mm/damon/core: use str_high_low() helper in damos_wmark_wait_us()
  seqlock: add missing parameter documentation for raw_seqcount_try_begin()
  mm/page-writeback: consolidate wb_thresh bumping logic into __wb_calc_thresh
  mm/page_alloc: remove the incorrect and misleading comment
  zram: remove zcomp_stream_put() from write_incompressible_page()
  mm: separate move/undo parts from migrate_pages_batch()
  mm/kfence: use str_write_read() helper in get_access_type()
  selftests/mm/mkdirty: fix memory leak in test_uffdio_copy()
  kasan: hw_tags: Use str_on_off() helper in kasan_init_hw_tags()
  selftests/mm: virtual_address_range: avoid reading from VM_IO mappings
  selftests/mm: vm_util: split up /proc/self/smaps parsing
  selftests/mm: virtual_address_range: unmap chunks after validation
  selftests/mm: virtual_address_range: mmap() without PROT_WRITE
  selftests/memfd/memfd_test: fix possible NULL pointer dereference
  mm: add FGP_DONTCACHE folio creation flag
  mm: call filemap_fdatawrite_range_kick() after IOCB_DONTCACHE issue
  ...
 2025-01-26 18:36:23 -08:00
Guo WeikangandAndrew Morton c6f239796b mm/memblock: add memblock_alloc_or_panic interface 
Before SLUB initialization, various subsystems used memblock_alloc to
allocate memory.  In most cases, when memory allocation fails, an
immediate panic is required.  To simplify this behavior and reduce
repetitive checks, introduce `memblock_alloc_or_panic`.  This function
ensures that memory allocation failures result in a panic automatically,
improving code readability and consistency across subsystems that require
this behavior.

[guoweikang.kernel@gmail.com: arch/s390: save_area_alloc default failure behavior changed to panic]
  Link: https://lkml.kernel.org/r/20250109033136.2845676-1-guoweikang.kernel@gmail.com
  Link: https://lore.kernel.org/lkml/Z2fknmnNtiZbCc7x@kernel.org/
Link: https://lkml.kernel.org/r/20250102072528.650926-1-guoweikang.kernel@gmail.com
Signed-off-by: Guo Weikang <guoweikang.kernel@gmail.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>	[m68k]
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>	[s390]
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:38 -08:00
Thorsten BlumandMadhavan Srinivasan 26bef359bc powerpc: Use str_on_off() helper in check_cache_coherency() 
Remove hard-coded strings by using the str_on_off() helper function.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20241220191705.1446-2-thorsten.blum@linux.dev
 2024-12-23 09:36:29 +05:30
Linus Torvalds 42d9e8b7cc Merge tag 'powerpc-6.13-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux 
Pull powerpc updates from Michael Ellerman:

 - Rework kfence support for the HPT MMU to work on systems with >= 16TB
   of RAM.

 - Remove the powerpc "maple" platform, used by the "Yellow Dog
   Powerstation".

 - Add support for DYNAMIC_FTRACE_WITH_CALL_OPS,
   DYNAMIC_FTRACE_WITH_DIRECT_CALLS & BPF Trampolines.

 - Add support for running KVM nested guests on Power11.

 - Other small features, cleanups and fixes.

Thanks to Amit Machhiwal, Arnd Bergmann, Christophe Leroy, Costa
Shulyupin, David Hunter, David Wang, Disha Goel, Gautam Menghani, Geert
Uytterhoeven, Hari Bathini, Julia Lawall, Kajol Jain, Keith Packard,
Lukas Bulwahn, Madhavan Srinivasan, Markus Elfring, Michal Suchanek,
Ming Lei, Mukesh Kumar Chaurasiya, Nathan Chancellor, Naveen N Rao,
Nicholas Piggin, Nysal Jan K.A, Paulo Miguel Almeida, Pavithra Prakash,
Ritesh Harjani (IBM), Rob Herring (Arm), Sachin P Bappalige, Shen
Lichuan, Simon Horman, Sourabh Jain, Thomas Weißschuh, Thorsten Blum,
Thorsten Leemhuis, Venkat Rao Bagalkote, Zhang Zekun, and zhang jiao.

* tag 'powerpc-6.13-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (89 commits)
  EDAC/powerpc: Remove PPC_MAPLE drivers
  powerpc/perf: Add per-task/process monitoring to vpa_pmu driver
  powerpc/kvm: Add vpa latency counters to kvm_vcpu_arch
  docs: ABI: sysfs-bus-event_source-devices-vpa-pmu: Document sysfs event format entries for vpa_pmu
  powerpc/perf: Add perf interface to expose vpa counters
  MAINTAINERS: powerpc: Mark Maddy as "M"
  powerpc/Makefile: Allow overriding CPP
  powerpc-km82xx.c: replace of_node_put() with __free
  ps3: Correct some typos in comments
  powerpc/kexec: Fix return of uninitialized variable
  macintosh: Use common error handling code in via_pmu_led_init()
  powerpc/powermac: Use of_property_match_string() in pmac_has_backlight_type()
  powerpc: remove dead config options for MPC85xx platform support
  powerpc/xive: Use cpumask_intersects()
  selftests/powerpc: Remove the path after initialization.
  powerpc/xmon: symbol lookup length fixed
  powerpc/ep8248e: Use %pa to format resource_size_t
  powerpc/ps3: Reorganize kerneldoc parameter names
  KVM: PPC: Book3S HV: Fix kmv -> kvm typo
  powerpc/sstep: make emulate_vsx_load and emulate_vsx_store static
  ...
 2024-11-23 10:44:31 -08:00
Thomas WeißschuhandThomas Gleixner 6142be7ed7 powerpc: Split systemcfg struct definitions out from vdso 
The systemcfg data has nothing to do anymore with the vdso.
Split it into a dedicated header file.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241010-vdso-generic-base-v1-27-b64f0842d512@linutronix.de
 2024-11-02 12:37:36 +01:00
Thomas WeißschuhandThomas Gleixner 1184674d6e powerpc: Split systemcfg data out of vdso data page 
The systemcfg data only has minimal overlap with the vdso data.
Splitting the two avoids mapping the implementation-defined vdso data
into /proc/ppc64/systemcfg.
It is also a preparation for the standardization of vdso data storage.

The only field actually used by both systemcfg and vdso is
tb_ticks_per_sec and it is only changed once during time_init().
Initialize it in both structures there.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241010-vdso-generic-base-v1-26-b64f0842d512@linutronix.de
 2024-11-02 12:37:36 +01:00
Ritesh Harjani (IBM)andMichael Ellerman 05b94cae1c powerpc/fadump: Move fadump_cma_init to setup_arch() after initmem_init() 
During early init CMA_MIN_ALIGNMENT_BYTES can be PAGE_SIZE,
since pageblock_order is still zero and it gets initialized
later during initmem_init() e.g.
setup_arch() -> initmem_init() -> sparse_init() -> set_pageblock_order()

One such use case where this causes issue is -
early_setup() -> early_init_devtree() -> fadump_reserve_mem() -> fadump_cma_init()

This causes CMA memory alignment check to be bypassed in
cma_init_reserved_mem(). Then later cma_activate_area() can hit
a VM_BUG_ON_PAGE(pfn & ((1 << order) - 1)) if the reserved memory
area was not pageblock_order aligned.

Fix it by moving the fadump_cma_init() after initmem_init(),
where other such cma reservations also gets called.

<stack trace>
==============
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10010
flags: 0x13ffff800000000(node=1|zone=0|lastcpupid=0x7ffff) CMA
raw: 013ffff800000000 5deadbeef0000100 5deadbeef0000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: VM_BUG_ON_PAGE(pfn & ((1 << order) - 1))
------------[ cut here ]------------
kernel BUG at mm/page_alloc.c:778!

Call Trace:
__free_one_page+0x57c/0x7b0 (unreliable)
free_pcppages_bulk+0x1a8/0x2c8
free_unref_page_commit+0x3d4/0x4e4
free_unref_page+0x458/0x6d0
init_cma_reserved_pageblock+0x114/0x198
cma_init_reserved_areas+0x270/0x3e0
do_one_initcall+0x80/0x2f8
kernel_init_freeable+0x33c/0x530
kernel_init+0x34/0x26c
ret_from_kernel_user_thread+0x14/0x1c

Fixes: 11ac3e87ce ("mm: cma: use pageblock_order as the single alignment")
Suggested-by: David Hildenbrand <david@redhat.com>
Reported-by: Sachin P Bappalige <sachinpb@linux.ibm.com>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/3ae208e48c0d9cefe53d2dc4f593388067405b7d.1729146153.git.ritesh.list@gmail.com
 2024-10-21 15:26:50 +11:00
Christophe LeroyandMichael Ellerman e7e846dc6c powerpc/mm: Fix boot warning with hugepages and CONFIG_DEBUG_VIRTUAL 
Booting with CONFIG_DEBUG_VIRTUAL leads to following warning when
passing hugepage reservation on command line:

  Kernel command line: hugepagesz=1g hugepages=1 hugepagesz=64m hugepages=1 hugepagesz=256m hugepages=1 noreboot
  HugeTLB: allocating 1 of page size 1.00 GiB failed.  Only allocated 0 hugepages.
  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 0 at arch/powerpc/include/asm/io.h:948 __alloc_bootmem_huge_page+0xd4/0x284
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper Not tainted 6.10.0-rc6-00396-g6b0e82791bd0-dirty #936
  Hardware name: MPC8544DS e500v2 0x80210030 MPC8544 DS
  NIP:  c1020240 LR: c10201d0 CTR: 00000000
  REGS: c13fdd30 TRAP: 0700   Not tainted  (6.10.0-rc6-00396-g6b0e82791bd0-dirty)
  MSR:  00021000 <CE,ME>  CR: 44084288  XER: 20000000

  GPR00: c10201d0 c13fde20 c130b560 e8000000 e8001000 00000000 00000000 c1420000
  GPR08: 00000000 00028001 00000000 00000004 44084282 01066ac0 c0eb7c9c efffe149
  GPR16: c0fc4228 0000005f ffffffff c0eb7d0c c0eb7cc0 c0eb7ce0 ffffffff 00000000
  GPR24: c1441cec efffe153 e8001000 c14240c0 00000000 c1441d64 00000000 e8000000
  NIP [c1020240] __alloc_bootmem_huge_page+0xd4/0x284
  LR [c10201d0] __alloc_bootmem_huge_page+0x64/0x284
  Call Trace:
  [c13fde20] [c10201d0] __alloc_bootmem_huge_page+0x64/0x284 (unreliable)
  [c13fde50] [c10207b8] hugetlb_hstate_alloc_pages+0x8c/0x3e8
  [c13fdeb0] [c1021384] hugepages_setup+0x240/0x2cc
  [c13fdef0] [c1000574] unknown_bootoption+0xfc/0x280
  [c13fdf30] [c0078904] parse_args+0x200/0x4c4
  [c13fdfa0] [c1000d9c] start_kernel+0x238/0x7d0
  [c13fdff0] [c0000434] set_ivor+0x12c/0x168
  Code: 554aa33e 7c042840 3ce0c142 80a7427c 5109a016 50caa016 7c9a2378 7fdcf378 4180000c 7c052040 41810160 7c095040 <0fe00000> 38c00000 40800108 3c60c0eb
  ---[ end trace 0000000000000000 ]---

This is due to virt_addr_valid() using high_memory before it is set.

high_memory is set in mem_init() using max_low_pfn, but max_low_pfn
is available long before, it is set in mem_topology_setup(). So just
like commit daa9ada209 ("powerpc/mm: Fix boot crash with FLATMEM")
moved the setting of max_mapnr immediately after the call to
mem_topology_setup(), the same can be done for high_memory.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/62b69c4baad067093f39e7e60df0fe27a86b8d2a.1723100702.git.christophe.leroy@csgroup.eu
 2024-08-12 21:50:20 +10:00
Thorsten BlumandMichael Ellerman 3e42e72796 powerpc: Use str_plural() in cpu_init_thread_core_maps() 
Fixes the following Coccinelle/coccicheck warning reported by
string_choices.cocci:

	opportunity for str_plural(tpc)

Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240331222249.107467-2-thorsten.blum@toblux.com
 2024-04-03 14:29:28 +11:00
Hari BathiniandMichael Ellerman 5c4233cc09 powerpc/kdump: Split KEXEC_CORE and CRASH_DUMP dependency 
Remove CONFIG_CRASH_DUMP dependency on CONFIG_KEXEC. CONFIG_KEXEC_CORE
was used at places where CONFIG_CRASH_DUMP or CONFIG_CRASH_RESERVE was
appropriate. Replace with appropriate #ifdefs to support CONFIG_KEXEC
and !CONFIG_CRASH_DUMP configuration option. Also, make CONFIG_FA_DUMP
dependent on CONFIG_CRASH_DUMP to avoid unmet dependencies for FA_DUMP
with !CONFIG_KEXEC_CORE configuration option.

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240226103010.589537-4-hbathini@linux.ibm.com
 2024-03-17 13:34:00 +11:00
Linus Torvalds 66a27abac3 Merge tag 'powerpc-6.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux 
Pull powerpc updates from Michael Ellerman:

 - Add AT_HWCAP3 and AT_HWCAP4 aux vector entries for future use
   by glibc

 - Add support for recognising the Power11 architected and raw PVRs

 - Add support for nr_cpus=n on the command line where the
   boot CPU is >= n

 - Add ppcxx_allmodconfig targets for all 32-bit sub-arches

 - Other small features, cleanups and fixes

Thanks to Akanksha J N, Brian King, Christophe Leroy, Dawei Li, Geoff
Levand, Greg Kroah-Hartman, Jan-Benedict Glaw, Kajol Jain, Kunwu Chan,
Li zeming, Madhavan Srinivasan, Masahiro Yamada, Nathan Chancellor,
Nicholas Piggin, Peter Bergner, Qiheng Lin, Randy Dunlap, Ricardo B.
Marliere, Rob Herring, Sathvika Vasireddy, Shrikanth Hegde, Uwe
Kleine-König, Vaibhav Jain, and Wen Xiong.

* tag 'powerpc-6.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (71 commits)
  powerpc/macio: Make remove callback of macio driver void returned
  powerpc/83xx: Fix build failure with FPU=n
  powerpc/64s: Fix get_hugepd_cache_index() build failure
  powerpc/4xx: Fix warp_gpio_leds build failure
  powerpc/amigaone: Make several functions static
  powerpc/embedded6xx: Fix no previous prototype for avr_uart_send() etc.
  macintosh/adb: make adb_dev_class constant
  powerpc: xor_vmx: Add '-mhard-float' to CFLAGS
  powerpc/fsl: Fix mfpmr() asm constraint error
  powerpc: Remove cpu-as-y completely
  powerpc/fsl: Modernise mt/mfpmr
  powerpc/fsl: Fix mfpmr build errors with newer binutils
  powerpc/64s: Use .machine power4 around dcbt
  powerpc/64s: Move dcbt/dcbtst sequence into a macro
  powerpc/mm: Code cleanup for __hash_page_thp
  powerpc/hv-gpci: Fix the H_GET_PERF_COUNTER_INFO hcall return value checks
  powerpc/irq: Allow softirq to hardirq stack transition
  powerpc: Stop using of_root
  powerpc/machdep: Define 'compatibles' property in ppc_md and use it
  of: Reimplement of_machine_is_compatible() using of_machine_compatible_match()
  ...
 2024-03-15 17:53:48 -07:00
Christophe LeroyandMichael Ellerman 28da734d58 powerpc/machdep: Define 'compatibles' property in ppc_md and use it 
Most probe functions that do not use the 'compatible' string do
nothing else than checking whether the machine is compatible with
one of the strings in a NULL terminated table of strings.

Define that table of strings in ppc_md structure and check it directly
from probe_machine() instead of using ppc_md.probe() for that.

Keep checking in ppc_md.probe() only for more complex probing.

All .compatible could be replaced with a single element NULL
terminated list but that's not worth the churn. Can be do incrementaly
in follow-up patches.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231214103152.12269-4-mpe@ellerman.id.au
 2024-03-03 22:20:29 +11:00
Baoquan HeandAndrew Morton 443cbaf9e2 crash: split vmcoreinfo exporting code out from crash_core.c 
Now move the relevant codes into separate files:
kernel/crash_reserve.c, include/linux/crash_reserve.h.

And add config item CRASH_RESERVE to control its enabling.

And also update the old ifdeffery of CONFIG_CRASH_CORE, including of
<linux/crash_core.h> and config item dependency on CRASH_CORE
accordingly.

And also do renaming as follows:
 - arch/xxx/kernel/{crash_core.c => vmcore_info.c}
because they are only related to vmcoreinfo exporting on x86, arm64,
riscv.

And also Remove config item CRASH_CORE, and rely on CONFIG_KEXEC_CORE to
decide if build in crash_core.c.

[yang.lee@linux.alibaba.com: remove duplicated include in vmcore_info.c]
  Link: https://lkml.kernel.org/r/20240126005744.16561-1-yang.lee@linux.alibaba.com
Link: https://lkml.kernel.org/r/20240124051254.67105-3-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Michael Kelley <mhklinux@outlook.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-02-23 17:48:22 -08:00
Michael Ellerman 0875f1ceba powerpc/smp: Remap boot CPU onto core 0 if >= nr_cpu_ids 
If nr_cpu_ids is too low to include the boot CPU, remap the boot CPU
onto logical core 0.

This is achieved in two stages. In early_init_dt_scan_cpus() the boot
CPU is renumbered to be on logical core 0, and the original boot core's
hardware ID is recorded.

Later in smp_setup_cpu_maps(), if the original boot core ID is set, the
logical CPU numbers on the 0th core are skipped in the normal device
tree search over CPU device tree nodes. Then the search is continued
until the device tree node matching the boot core is found, and those
CPUs are assigned the CPU numbers starting at 0.

This allows kdump kernels to be booted with low values for nr_cpu_ids
to conserve memory, while also allowing the crashing/boot CPU to be
any CPU.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Wen Xiong <wenxiong@us.ibm.com>
Link: https://msgid.link/20231229120107.2281153-5-mpe@ellerman.id.au
 2024-02-15 00:14:05 +11:00
Michael Ellerman 9832de6544 powerpc/smp: Factor out assign_threads() 
Factor out the for loop that assigns CPU numbers to threads of a core.
The function takes the next CPU number to use as input, and returns the
next available CPU number after the threads has been assigned.

This will allow a subsequent change to assign threads out of order.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231229120107.2281153-4-mpe@ellerman.id.au
 2024-02-15 00:14:05 +11:00
Michael Ellerman dca79603fb powerpc/smp: Lookup avail once per device tree node 
The of_device_is_available() check only needs to be done once per device
node, there's no need to repeat it for each thread. Move it out of the
loop.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231229120107.2281153-3-mpe@ellerman.id.au
 2024-02-15 00:14:04 +11:00
Linus Torvalds 1f24458a10 Merge tag 'tty-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty 
Pull tty and serial updates from Greg KH:
 "Here is the big set of tty/serial driver changes for 6.7-rc1. Included
  in here are:

   - console/vgacon cleanups and removals from Arnd

   - tty core and n_tty cleanups from Jiri

   - lots of 8250 driver updates and cleanups

   - sc16is7xx serial driver updates

   - dt binding updates

   - first set of port lock wrapers from Thomas for the printk fixes
     coming in future releases

   - other small serial and tty core cleanups and updates

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (193 commits)
  serdev: Replace custom code with device_match_acpi_handle()
  serdev: Simplify devm_serdev_device_open() function
  serdev: Make use of device_set_node()
  tty: n_gsm: add copyright Siemens Mobility GmbH
  tty: n_gsm: fix race condition in status line change on dead connections
  serial: core: Fix runtime PM handling for pending tx
  vgacon: fix mips/sibyte build regression
  dt-bindings: serial: drop unsupported samsung bindings
  tty: serial: samsung: drop earlycon support for unsupported platforms
  tty: 8250: Add note for PX-835
  tty: 8250: Fix IS-200 PCI ID comment
  tty: 8250: Add Brainboxes Oxford Semiconductor-based quirks
  tty: 8250: Add support for Intashield IX cards
  tty: 8250: Add support for additional Brainboxes PX cards
  tty: 8250: Fix up PX-803/PX-857
  tty: 8250: Fix port count of PX-257
  tty: 8250: Add support for Intashield IS-100
  tty: 8250: Add support for Brainboxes UP cards
  tty: 8250: Add support for additional Brainboxes UC cards
  tty: 8250: Remove UC-257 and UC-431
  ...
 2023-11-03 15:44:25 -10:00
Linus Torvalds 31e5f934ff Merge tag 'trace-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace 
Pull tracing updates from Steven Rostedt:

 - Remove eventfs_file descriptor

   This is the biggest change, and the second part of making eventfs
   create its files dynamically.

   In 6.6 the first part was added, and that maintained a one to one
   mapping between eventfs meta descriptors and the directories and file
   inodes and dentries that were dynamically created. The directories
   were represented by a eventfs_inode and the files were represented by
   a eventfs_file.

   In v6.7 the eventfs_file is removed. As all events have the same
   directory make up (sched_switch has an "enable", "id", "format", etc
   files), the handing of what files are underneath each leaf eventfs
   directory is moved back to the tracing subsystem via a callback.

   When an event is added to the eventfs, it registers an array of
   evenfs_entry's. These hold the names of the files and the callbacks
   to call when the file is referenced. The callback gets the name so
   that the same callback may be used by multiple files. The callback
   then supplies the filesystem_operations structure needed to create
   this file.

   This has brought the memory footprint of creating multiple eventfs
   instances down by 2 megs each!

 - User events now has persistent events that are not associated to a
   single processes. These are privileged events that hang around even
   if no process is attached to them

 - Clean up of seq_buf

   There's talk about using seq_buf more to replace strscpy() and
   friends. But this also requires some minor modifications of seq_buf
   to be able to do this

 - Expand instance ring buffers individually

   Currently if boot up creates an instance, and a trace event is
   enabled on that instance, the ring buffer for that instance and the
   top level ring buffer are expanded (1.4 MB per CPU). This wastes
   memory as this happens when nothing is using the top level instance

 - Other minor clean ups and fixes

* tag 'trace-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (34 commits)
  seq_buf: Export seq_buf_puts()
  seq_buf: Export seq_buf_putc()
  eventfs: Use simple_recursive_removal() to clean up dentries
  eventfs: Remove special processing of dput() of events directory
  eventfs: Delete eventfs_inode when the last dentry is freed
  eventfs: Hold eventfs_mutex when calling callback functions
  eventfs: Save ownership and mode
  eventfs: Test for ei->is_freed when accessing ei->dentry
  eventfs: Have a free_ei() that just frees the eventfs_inode
  eventfs: Remove "is_freed" union with rcu head
  eventfs: Fix kerneldoc of eventfs_remove_rec()
  tracing: Have the user copy of synthetic event address use correct context
  eventfs: Remove extra dget() in eventfs_create_events_dir()
  tracing: Have trace_event_file have ref counters
  seq_buf: Introduce DECLARE_SEQ_BUF and seq_buf_str()
  eventfs: Fix typo in eventfs_inode union comment
  eventfs: Fix WARN_ON() in create_file_dentry()
  powerpc: Remove initialisation of readpos
  tracing/histograms: Simplify last_cmd_set()
  seq_buf: fix a misleading comment
  ...
 2023-11-03 07:41:18 -10:00
Matthew Wilcox (Oracle)andSteven Rostedt (Google) 0f7f544af6 powerpc: Remove initialisation of readpos 
While powerpc doesn't use the seq_buf readpos, it did explicitly
initialise it for no good reason.

Link: https://lore.kernel.org/linux-trace-kernel/20231024145600.739451-1-willy@infradead.org

Cc: Christoph Hellwig <hch@lst.de>
Cc: Justin Stitt <justinstitt@google.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Kees Cook <keescook@chromium.org>
Fixes: d0ed46b603 ("tracing: Move readpos from seq_buf to trace_seq")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
 2023-10-25 21:25:51 -04:00
Michael Ellerman daa9ada209 powerpc/mm: Fix boot crash with FLATMEM 
Erhard reported that his G5 was crashing with v6.6-rc kernels:

  mpic: Setting up HT PICs workarounds for U3/U4
  BUG: Unable to handle kernel data access at 0xfeffbb62ffec65fe
  Faulting instruction address: 0xc00000000005dc40
  Oops: Kernel access of bad area, sig: 11 [#1]
  BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2 PowerMac
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper/0 Tainted: G                T  6.6.0-rc3-PMacGS #1
  Hardware name: PowerMac11,2 PPC970MP 0x440101 PowerMac
  NIP:  c00000000005dc40 LR: c000000000066660 CTR: c000000000007730
  REGS: c0000000022bf510 TRAP: 0380   Tainted: G                T (6.6.0-rc3-PMacGS)
  MSR:  9000000000001032 <SF,HV,ME,IR,DR,RI>  CR: 44004242  XER: 00000000
  IRQMASK: 3
  GPR00: 0000000000000000 c0000000022bf7b0 c0000000010c0b00 00000000000001ac
  GPR04: 0000000003c80000 0000000000000300 c0000000f20001ae 0000000000000300
  GPR08: 0000000000000006 feffbb62ffec65ff 0000000000000001 0000000000000000
  GPR12: 9000000000001032 c000000002362000 c000000000f76b80 000000000349ecd8
  GPR16: 0000000002367ba8 0000000002367f08 0000000000000006 0000000000000000
  GPR20: 00000000000001ac c000000000f6f920 c0000000022cd985 000000000000000c
  GPR24: 0000000000000300 00000003b0a3691d c0003e008030000e 0000000000000000
  GPR28: c00000000000000c c0000000f20001ee feffbb62ffec65fe 00000000000001ac
  NIP hash_page_do_lazy_icache+0x50/0x100
  LR  __hash_page_4K+0x420/0x590
  Call Trace:
    hash_page_mm+0x364/0x6f0
    do_hash_fault+0x114/0x2b0
    data_access_common_virt+0x198/0x1f0
  --- interrupt: 300 at mpic_init+0x4bc/0x10c4
  NIP:  c000000002020a5c LR: c000000002020a04 CTR: 0000000000000000
  REGS: c0000000022bf9f0 TRAP: 0300   Tainted: G                T (6.6.0-rc3-PMacGS)
  MSR:  9000000000001032 <SF,HV,ME,IR,DR,RI>  CR: 24004248  XER: 00000000
  DAR: c0003e008030000e DSISR: 40000000 IRQMASK: 1
  ...
  NIP mpic_init+0x4bc/0x10c4
  LR  mpic_init+0x464/0x10c4
  --- interrupt: 300
    pmac_setup_one_mpic+0x258/0x2dc
    pmac_pic_init+0x28c/0x3d8
    init_IRQ+0x90/0x140
    start_kernel+0x57c/0x78c
    start_here_common+0x1c/0x20

A bisect pointed to the breakage beginning with commit 9fee28baa6 ("powerpc:
implement the new page table range API").

Analysis of the oops pointed to a struct page with a corrupted
compound_head being loaded via page_folio() -> _compound_head() in
hash_page_do_lazy_icache().

The access by the mpic code is to an MMIO address, so the expectation
is that the struct page for that address would be initialised by
init_unavailable_range(), as pointed out by Aneesh.

Instrumentation showed that was not the case, which eventually lead to
the realisation that pfn_valid() was returning false for that address,
causing the struct page to not be initialised.

Because the system is using FLATMEM, the version of pfn_valid() in
memory_model.h is used:

static inline int pfn_valid(unsigned long pfn)
{
	...
	return pfn >= pfn_offset && (pfn - pfn_offset) < max_mapnr;
}

Which relies on max_mapnr being initialised. Early in boot max_mapnr is
zero meaning no PFNs are valid.

max_mapnr is initialised in mem_init() called via:

  start_kernel()
    mm_core_init()  # init/main.c:928
      mem_init()

But that is too late for the usage in init_unavailable_range() called via:

  start_kernel()
    setup_arch()    # init/main.c:893
      paging_init()
        free_area_init()
          init_unavailable_range()

Although max_mapnr is currently set in mem_init(), the value is actually
already available much earlier, as soon as mem_topology_setup() has
completed, which is also before paging_init() is called. So move the
initialisation there, which causes paging_init() to correctly initialise
the struct page and fixes the bug.

This bug seems to have been lurking for years, but went unnoticed
because the pre-folio code was inspecting the uninitialised page->flags
but not dereferencing it.

Thanks to Erhard and Aneesh for help debugging.

Reported-by: Erhard Furtner <erhard_f@mailbox.org>
Closes: https://lore.kernel.org/all/20230929132750.3cd98452@yea/
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231023112500.1550208-1-mpe@ellerman.id.au
 2023-10-23 22:50:15 +11:00