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 9fee28baa601 ("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
The DT of_device.h and of_platform.h date back to the separate of_platform_bus_type before it as merged into the regular platform bus. As part of that merge prepping Arm DT support 13 years ago, they "temporarily" include each other. They also include platform_device.h and of.h. As a result, there's a pretty much random mix of those include files used throughout the tree. In order to detangle these headers and replace the implicit includes with struct declarations, users need to explicitly include the correct includes. Signed-off-by: Rob Herring <robh@kernel.org> [mpe: Fixup maple/setup.c which needs platform_device] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230724210247.778034-1-robh@kernel.org
init_mm mm_cpumask and context.active_cpus is not maintained at boot and hotplug. This seems to be harmless because init_mm does not have a userspace and so never gets user TLBs flushed, but it looks odd and it prevents some sanity checks being added. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230524060821.148015-2-npiggin@gmail.com
Most probe functions do nothing else than checking whether the machine is compatible to a given string. Define that string 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. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/6cb9865d916231c38401ba34ad1a98c249fae135.1676711562.git.christophe.leroy@csgroup.eu
The early paca and boot cpuid dance is complicated and currently does not quite work as expected for boot cpuid != 0 cases. early_init_devtree() currently allocates the paca_ptrs and boot cpuid paca, but until that returns and early_setup() calls setup_paca(), this thread is currently still executing with smp_processor_id() == 0. One problem this causes is the paca_ptrs[smp_processor_id()] pointer is poisoned, so valid_emergency_stack() (any backtrace) and any similar users will crash. Another is that the hardware id which is set here will not be returned by get_hard_smp_processor_id(smp_processor_id()), but it would work correctly for boot_cpuid == 0, which could lead to difficult to reproduce or find bugs. The hard id does not seem to be used by the rest of early_init_devtree(), it just looks like all this code might have been put here to allocate somewhere to store boot CPU hardware id while scanning the devtree. Rearrange things so the hwid is put in a global variable like boot_cpuid, and do all the paca allocation and boot paca setup in the 64-bit early_setup() after we have everything ready to go. The paca_ptrs[0] re-poisoning code in early_setup does not seem to have ever worked, because paca_ptrs[0] was never not-poisoned when boot_cpuid is not 0. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Fix build error on 32-bit] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20221216115930.2667772-4-npiggin@gmail.com
The <asm/archrandom.h> header is a random.c private detail, not something to be called by other code. As such, don't make it automatically available by way of random.h. Cc: Michael Ellerman <mpe@ellerman.id.au> Acked-by: Heiko Carstens <hca@linux.ibm.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Create a hardware description string, which we will use to record various details of the hardware platform we are running on. Print the accumulated description at boot, and use it to set the generic description which is printed in oopses. To begin with add ppc_md.name, aka the "machine description". Example output at boot with the full series applied: Linux version 6.0.0-rc2-gcc-11.1.0-00199-g893f9007a5ce-dirty (michael@alpine1-p1) (powerpc64-linux-gcc (GCC) 11.1.0, GNU ld (GNU Binutils) 2.36.1) #844 SMP Thu Sep 29 22:29:53 AEST 2022 Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1200 0xf000005 of:SLOF,git-5b4c5a pSeries printk: bootconsole [udbg0] enabled Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220930082709.55830-1-mpe@ellerman.id.au
Pull bitmap updates from Yury Norov: - fix the duplicated comments on bitmap_to_arr64() (Qu Wenruo) - optimize out non-atomic bitops on compile-time constants (Alexander Lobakin) - cleanup bitmap-related headers (Yury Norov) - x86/olpc: fix 'logical not is only applied to the left hand side' (Alexander Lobakin) - lib/nodemask: inline wrappers around bitmap (Yury Norov) * tag 'bitmap-6.0-rc1' of https://github.com/norov/linux: (26 commits) lib/nodemask: inline next_node_in() and node_random() powerpc: drop dependency on <asm/machdep.h> in archrandom.h x86/olpc: fix 'logical not is only applied to the left hand side' lib/cpumask: move some one-line wrappers to header file headers/deps: mm: align MANITAINERS and Docs with new gfp.h structure headers/deps: mm: Split <linux/gfp_types.h> out of <linux/gfp.h> headers/deps: mm: Optimize <linux/gfp.h> header dependencies lib/cpumask: move trivial wrappers around find_bit to the header lib/cpumask: change return types to unsigned where appropriate cpumask: change return types to bool where appropriate lib/bitmap: change type of bitmap_weight to unsigned long lib/bitmap: change return types to bool where appropriate arm: align find_bit declarations with generic kernel iommu/vt-d: avoid invalid memory access via node_online(NUMA_NO_NODE) lib/test_bitmap: test the tail after bitmap_to_arr64() lib/bitmap: fix off-by-one in bitmap_to_arr64() lib: test_bitmap: add compile-time optimization/evaluations assertions bitmap: don't assume compiler evaluates small mem*() builtins calls net/ice: fix initializing the bitmap in the switch code bitops: let optimize out non-atomic bitops on compile-time constants ...
archrandom.h includes <asm/machdep.h> to refer ppc_md. This causes
circular header dependency, if generic nodemask.h includes random.h:
In file included from include/linux/cred.h:16,
from include/linux/seq_file.h:13,
from arch/powerpc/include/asm/machdep.h:6,
from arch/powerpc/include/asm/archrandom.h:5,
from include/linux/random.h:109,
from include/linux/nodemask.h:97,
from include/linux/list_lru.h:12,
from include/linux/fs.h:13,
from include/linux/compat.h:17,
from arch/powerpc/kernel/asm-offsets.c:12:
include/linux/sched.h:1203:9: error: unknown type name 'nodemask_t'
1203 | nodemask_t mems_allowed;
| ^~~~~~~~~~
Fix it by removing <asm/machdep.h> dependency from archrandom.h
Now as arch_get_random_seed_long() moved to c-file, and not exported,
it's not available for modules. As Michael Ellerman says:
I think we actually don't need it exported to modules, I think it's
a private detail of the RNG <-> architecture interface, not something
that modules should be calling.
CC: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Michael Ellerman <mpe@ellerman.id.au>
CC: Paul Mackerras <paulus@samba.org>
CC: Rasmus Villemoes <linux@rasmusvillemoes.dk>
CC: Stephen Rothwell <sfr@canb.auug.org.au>
CC: linuxppc-dev@lists.ozlabs.org
Suggested-by: Michael Ellerman <mpe@ellerman.id.au> (for non-exporting)
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
After commit 11ac3e87ce09 ("mm: cma: use pageblock_order as the single
alignment") there is an error at boot about the KVM CMA reservation
failing, eg:
kvm_cma_reserve: reserving 6553 MiB for global area
cma: Failed to reserve 6553 MiB
That makes it impossible to start KVM guests using the hash MMU with
more than 2G of memory, because the VM is unable to allocate a large
enough region for the hash page table, eg:
$ qemu-system-ppc64 -enable-kvm -M pseries -m 4G ...
qemu-system-ppc64: Failed to allocate KVM HPT of order 25: Cannot allocate memory
Aneesh pointed out that this happens because when kvm_cma_reserve() is
called, pageblock_order has not been initialised yet, and is still zero,
causing the checks in cma_init_reserved_mem() against
CMA_MIN_ALIGNMENT_PAGES to fail.
Fix it by moving the call to kvm_cma_reserve() after initmem_init(). The
pageblock_order is initialised in sparse_init() which is called from
initmem_init().
Also move the hugetlb CMA reservation.
Fixes: 11ac3e87ce09 ("mm: cma: use pageblock_order as the single alignment")
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220616120033.1976732-1-mpe@ellerman.id.au