Re: [PATCH v3 8/8] lib: test for_each_numa_cpus()

[Guenter Roeck]

Hi,

On Sun, Apr 30, 2023 at 10:18:09AM -0700, Yury Norov wrote:
> Test for_each_numa_cpus() output to ensure that:
>  - all CPUs are picked from NUMA nodes with non-decreasing distances to the
>    original node; 
>  - only online CPUs are enumerated;
>  - the macro enumerates each online CPUs only once;
>  - enumeration order is consistent with cpumask_local_spread().
> 
> The latter is an implementation-defined behavior. If cpumask_local_spread()
> or for_each_numa_cpu() will get changed in future, the subtest may need
> to be adjusted or even removed, as appropriate.
> 
> It's useful now because some architectures don't implement numa_distance(),
> and generic implementation only distinguishes local and remote nodes, which
> doesn't allow to test the for_each_numa_cpu() properly.
> 

This patch results in a crash when testing sparc64 images with qemu.

[    4.178301] Unable to handle kernel NULL pointer dereference
[    4.178836] tsk->{mm,active_mm}->context = 0000000000000000
[    4.179280] tsk->{mm,active_mm}->pgd = fffff80000402000
[    4.179710]               \|/ ____ \|/
[    4.179710]               "@'/ .. \`@"
[    4.179710]               /_| \__/ |_\
[    4.179710]                  \__U_/
[    4.180307] swapper/0(1): Oops [#1]
[    4.181070] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G                 N 6.5.0-rc2+ #1
[    4.181720] TSTATE: 0000000011001600 TPC: 000000000094d800 TNPC: 000000000094d804 Y: 00000000    Tainted: G                 N
[    4.182324] TPC: <_find_next_and_bit+0x20/0xa0>
[    4.183136] g0: 0000000000530b90 g1: 0000000000000000 g2: 0000000000000000 g3: ffffffffffffffff
[    4.183611] g4: fffff80004200020 g5: fffff8001dc42000 g6: fffff80004168000 g7: 0000000000000000
[    4.184080] o0: 0000000000000001 o1: 0000000001a28190 o2: 0000000000000009 o3: 00000000020e9e28
[    4.184549] o4: 0000000000000200 o5: 0000000000000001 sp: fffff8000416af11 ret_pc: 0000000000f6529c
[    4.185020] RPC: <lock_is_held_type+0xbc/0x180>
[    4.185477] l0: 0000000001bbfa58 l1: 0000000000000000 l2: 00000000020ea228 l3: fffff80004200aa0
[    4.185950] l4: 81b8e1e5a4e0c637 l5: 000000000192b000 l6: 00000000023b3800 l7: 00000000020e9e28
[    4.186417] i0: 000000000192a3f8 i1: 0000000000000000 i2: 0000000000000001 i3: 0000000000000000
[    4.186885] i4: 0000000000000001 i5: fffff80004200aa0 i6: fffff8000416afc1 i7: 00000000004c79bc
[    4.187356] I7: <sched_numa_find_next_cpu+0x13c/0x180>
[    4.187821] Call Trace:
[    4.188274] [<00000000004c79bc>] sched_numa_find_next_cpu+0x13c/0x180
[    4.188762] [<0000000001b77c10>] test_for_each_numa_cpu+0x164/0x37c
[    4.189196] [<0000000001b7878c>] test_bitmap_init+0x964/0x9f4
[    4.189637] [<0000000000427f40>] do_one_initcall+0x60/0x340
[    4.190069] [<0000000001b56f34>] kernel_init_freeable+0x1bc/0x228
[    4.190496] [<0000000000f66aa4>] kernel_init+0x18/0x134
[    4.190911] [<00000000004060e8>] ret_from_fork+0x1c/0x2c
[    4.191326] [<0000000000000000>] 0x0
[    4.191827] Disabling lock debugging due to kernel taint
[    4.192363] Caller[00000000004c79bc]: sched_numa_find_next_cpu+0x13c/0x180
[    4.192825] Caller[0000000001b77c10]: test_for_each_numa_cpu+0x164/0x37c
[    4.193255] Caller[0000000001b7878c]: test_bitmap_init+0x964/0x9f4
[    4.193681] Caller[0000000000427f40]: do_one_initcall+0x60/0x340
[    4.194097] Caller[0000000001b56f34]: kernel_init_freeable+0x1bc/0x228
[    4.194516] Caller[0000000000f66aa4]: kernel_init+0x18/0x134
[    4.194922] Caller[00000000004060e8]: ret_from_fork+0x1c/0x2c
[    4.195326] Caller[0000000000000000]: 0x0
[    4.195728] Instruction DUMP:
[    4.195762]  8328b003
[    4.196237]  8728d01b
[    4.196600]  d05e0001
[    4.196956] <ce5e4001>
[    4.197311]  900a0007
[    4.197669]  900a0003
[    4.198024]  0ac20013
[    4.198379]  bb28b006
[    4.198733]  8400a001
[    4.199093]
[    4.199873] note: swapper/0[1] exited with preempt_count 1
[    4.200539] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009

Bisect log attached.

Guenter

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# bad: [ae867bc97b713121b2a7f5fcac68378a0774739b] Add linux-next specific files for 20230721
# good: [fdf0eaf11452d72945af31804e2a1048ee1b574c] Linux 6.5-rc2
git bisect start 'HEAD' 'v6.5-rc2'
# good: [f09bf8f6c8cbbff6f52523abcda88c86db72e31c] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git
git bisect good f09bf8f6c8cbbff6f52523abcda88c86db72e31c
# good: [86374a6210aeebceb927204d80f9e65739134bc3] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git
git bisect good 86374a6210aeebceb927204d80f9e65739134bc3
# good: [d588c93cae9e3dff15d125e755edcba5d842f41a] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
git bisect good d588c93cae9e3dff15d125e755edcba5d842f41a
# good: [3c3990d304820b12a07c77a6e091d6711b31f8e5] Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/soundwire.git
git bisect good 3c3990d304820b12a07c77a6e091d6711b31f8e5
# good: [b80a945fabd7acc5984d421c73fa0b667195adb7] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git
git bisect good b80a945fabd7acc5984d421c73fa0b667195adb7
# good: [22c343fad503564a2ef5c6aff1dcb1ec0640006e] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching
git bisect good 22c343fad503564a2ef5c6aff1dcb1ec0640006e
# good: [bf05130eebc3265314f14c1314077f500a5c8d98] Merge branch 'mhi-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mani/mhi.git
git bisect good bf05130eebc3265314f14c1314077f500a5c8d98
# good: [18eea171e03cc2b30fe7c11d6e94521d905026f0] Merge branch 'rust-next' of https://github.com/Rust-for-Linux/linux.git
git bisect good 18eea171e03cc2b30fe7c11d6e94521d905026f0
# bad: [94b1547668965e1fde8bde3638845ab582b40034] lib: test for_each_numa_cpus()
git bisect bad 94b1547668965e1fde8bde3638845ab582b40034
# good: [310ae5d9d46b65fdbd18ac1e5bd03681fbc19ae8] sched/topology: introduce sched_numa_find_next_cpu()
git bisect good 310ae5d9d46b65fdbd18ac1e5bd03681fbc19ae8
# good: [a4be5fa84bb269886310f563e9095e8164f82c8c] net: mlx5: switch comp_irqs_request() to using for_each_numa_cpu
git bisect good a4be5fa84bb269886310f563e9095e8164f82c8c
# good: [b9833b80d87030b0def7aeda88471ac7f6acd3cb] sched: drop for_each_numa_hop_mask()
git bisect good b9833b80d87030b0def7aeda88471ac7f6acd3cb
# first bad commit: [94b1547668965e1fde8bde3638845ab582b40034] lib: test for_each_numa_cpus()