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Christian Loehle b3ec50cc5e sched: Fix sched_numa_find_nth_cpu() if mask offline
commit 5ebf512f33 upstream.

sched_numa_find_nth_cpu() uses a bsearch to look for the 'closest'
CPU in sched_domains_numa_masks and given cpus mask. However they
might not intersect if all CPUs in the cpus mask are offline. bsearch
will return NULL in that case, bail out instead of dereferencing a
bogus pointer.

The previous behaviour lead to this bug when using maxcpus=4 on an
rk3399 (LLLLbb) (i.e. booting with all big CPUs offline):

[    1.422922] Unable to handle kernel paging request at virtual address ffffff8000000000
[    1.423635] Mem abort info:
[    1.423889]   ESR = 0x0000000096000006
[    1.424227]   EC = 0x25: DABT (current EL), IL = 32 bits
[    1.424715]   SET = 0, FnV = 0
[    1.424995]   EA = 0, S1PTW = 0
[    1.425279]   FSC = 0x06: level 2 translation fault
[    1.425735] Data abort info:
[    1.425998]   ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000
[    1.426499]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[    1.426952]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[    1.427428] swapper pgtable: 4k pages, 39-bit VAs, pgdp=0000000004a9f000
[    1.428038] [ffffff8000000000] pgd=18000000f7fff403, p4d=18000000f7fff403, pud=18000000f7fff403, pmd=0000000000000000
[    1.429014] Internal error: Oops: 0000000096000006 [#1]  SMP
[    1.429525] Modules linked in:
[    1.429813] CPU: 3 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.17.0-rc4-dirty #343 PREEMPT
[    1.430559] Hardware name: Pine64 RockPro64 v2.1 (DT)
[    1.431012] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[    1.431634] pc : sched_numa_find_nth_cpu+0x2a0/0x488
[    1.432094] lr : sched_numa_find_nth_cpu+0x284/0x488
[    1.432543] sp : ffffffc084e1b960
[    1.432843] x29: ffffffc084e1b960 x28: ffffff80078a8800 x27: ffffffc0846eb1d0
[    1.433495] x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000
[    1.434144] x23: 0000000000000000 x22: fffffffffff7f093 x21: ffffffc081de6378
[    1.434792] x20: 0000000000000000 x19: 0000000ffff7f093 x18: 00000000ffffffff
[    1.435441] x17: 3030303866666666 x16: 66663d736b73616d x15: ffffffc104e1b5b7
[    1.436091] x14: 0000000000000000 x13: ffffffc084712860 x12: 0000000000000372
[    1.436739] x11: 0000000000000126 x10: ffffffc08476a860 x9 : ffffffc084712860
[    1.437389] x8 : 00000000ffffefff x7 : ffffffc08476a860 x6 : 0000000000000000
[    1.438036] x5 : 000000000000bff4 x4 : 0000000000000000 x3 : 0000000000000000
[    1.438683] x2 : 0000000000000000 x1 : ffffffc0846eb000 x0 : ffffff8000407b68
[    1.439332] Call trace:
[    1.439559]  sched_numa_find_nth_cpu+0x2a0/0x488 (P)
[    1.440016]  smp_call_function_any+0xc8/0xd0
[    1.440416]  armv8_pmu_init+0x58/0x27c
[    1.440770]  armv8_cortex_a72_pmu_init+0x20/0x2c
[    1.441199]  arm_pmu_device_probe+0x1e4/0x5e8
[    1.441603]  armv8_pmu_device_probe+0x1c/0x28
[    1.442007]  platform_probe+0x5c/0xac
[    1.442347]  really_probe+0xbc/0x298
[    1.442683]  __driver_probe_device+0x78/0x12c
[    1.443087]  driver_probe_device+0xdc/0x160
[    1.443475]  __driver_attach+0x94/0x19c
[    1.443833]  bus_for_each_dev+0x74/0xd4
[    1.444190]  driver_attach+0x24/0x30
[    1.444525]  bus_add_driver+0xe4/0x208
[    1.444874]  driver_register+0x60/0x128
[    1.445233]  __platform_driver_register+0x24/0x30
[    1.445662]  armv8_pmu_driver_init+0x28/0x4c
[    1.446059]  do_one_initcall+0x44/0x25c
[    1.446416]  kernel_init_freeable+0x1dc/0x3bc
[    1.446820]  kernel_init+0x20/0x1d8
[    1.447151]  ret_from_fork+0x10/0x20
[    1.447493] Code: 90022e21 f000e5f5 910de2b5 2a1703e2 (f8767803)
[    1.448040] ---[ end trace 0000000000000000 ]---
[    1.448483] note: swapper/0[1] exited with preempt_count 1
[    1.449047] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[    1.449741] SMP: stopping secondary CPUs
[    1.450105] Kernel Offset: disabled
[    1.450419] CPU features: 0x000000,00080000,20002001,0400421b
[    1.450935] Memory Limit: none
[    1.451217] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]---

Yury: with the fix, the function returns cpu == nr_cpu_ids, and later in

	smp_call_function_any ->
	  smp_call_function_single ->
	     generic_exec_single

we test the cpu for '>= nr_cpu_ids' and return -ENXIO. So everything is
handled correctly.

Fixes: cd7f55359c ("sched: add sched_numa_find_nth_cpu()")
Cc: stable@vger.kernel.org
Signed-off-by: Christian Loehle <christian.loehle@arm.com>
Signed-off-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-09-09 18:58:16 +02:00
arch x86/mm/64: define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() 2025-09-09 18:58:15 +02:00
block blk-zoned: Fix a lockdep complaint about recursive locking 2025-09-04 15:31:54 +02:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: jitter - fix intermediary handling 2025-08-20 18:30:42 +02:00
Documentation dt-bindings: display/msm: qcom,mdp5: drop lut clock 2025-09-04 15:31:48 +02:00
drivers pcmcia: Fix a NULL pointer dereference in __iodyn_find_io_region() 2025-09-09 18:58:15 +02:00
fs fs: writeback: fix use-after-free in __mark_inode_dirty() 2025-09-09 18:58:03 +02:00
include mm: move page table sync declarations to linux/pgtable.h 2025-09-09 18:58:15 +02:00
init io_uring: fix breakage in EXPERT menu 2025-08-15 12:13:32 +02:00
io_uring io_uring/msg_ring: ensure io_kiocb freeing is deferred for RCU 2025-09-09 18:58:15 +02:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:11:22 +01:00
kernel sched: Fix sched_numa_find_nth_cpu() if mask offline 2025-09-09 18:58:16 +02:00
lib lib/sbitmap: convert shallow_depth from one word to the whole sbitmap 2025-08-20 18:30:49 +02:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm: slub: avoid wake up kswapd in set_track_prepare 2025-09-09 18:58:16 +02:00
net net: atm: fix memory leak in atm_register_sysfs when device_register fail 2025-09-09 18:58:13 +02:00
rust rust: alloc: fix rusttest by providing Cmalloc::aligned_layout too 2025-08-28 16:31:13 +02:00
samples samples: mei: Fix building on musl libc 2025-08-15 12:13:38 +02:00
scripts kconfig: lxdialog: fix 'space' to (de)select options 2025-08-20 18:30:48 +02:00
security apparmor: Fix 8-byte alignment for initial dfa blob streams 2025-08-28 16:30:56 +02:00
sound ALSA: usb-audio: Add mute TLV for playback volumes on some devices 2025-09-09 18:58:14 +02:00
tools selftest: net: Fix weird setsockopt() in bind_bhash.c. 2025-09-09 18:58:14 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-03-13 13:02:18 +01:00
virt KVM: Allow CPU to reschedule while setting per-page memory attributes 2025-07-17 18:37:08 +02:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-08-01 09:48:44 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: introduce .clippy.toml 2025-03-13 13:01:42 +01:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: Update Alexey Makhalov's email address 2025-05-22 14:29:46 +02:00
Makefile Linux 6.12.45 2025-09-04 15:31:56 +02:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.