Commits
Christopher M. Riedl committed 405efc5980f
powerpc/spinlocks: Fix oops in __spin_yield() on bare metal
Booting w/ppc64le_defconfig + CONFIG_PREEMPT on bare metal results in
the oops below due to calling into __spin_yield() when not running in
an SPLPAR, which means lppaca pointers are NULL.
We fixed a similar case previously in commit a6201da34ff9 ("powerpc:
Fix oops due to bad access of lppaca on bare metal"), by adding SPLPAR
checks in lppaca_shared_proc(). However when PREEMPT is enabled we can
call __spin_yield() directly from arch_spin_yield().
To fix it add spin_yield() and rw_yield() which check that
shared-processor LPAR is enabled before calling the SPLPAR-only
implementation of each.
BUG: Kernel NULL pointer dereference at 0x00000100
Faulting instruction address: 0xc000000000097f88
Oops: Kernel access of bad area, sig: 7 [#1]
LE PAGE_SIZE=64K MMU=Radix MMU=Hash PREEMPT SMP NR_CPUS=2048 NUMA PowerNV
Modules linked in:
CPU: 0 PID: 2 Comm: kthreadd Not tainted 5.2.0-rc6-00491-g249155c20f9b #28
NIP: c000000000097f88 LR: c000000000c07a88 CTR: c00000000015ca10
REGS: c0000000727079f0 TRAP: 0300 Not tainted (5.2.0-rc6-00491-g249155c20f9b)
MSR: 9000000002009033 <SF,HV,VEC,EE,ME,IR,DR,RI,LE> CR: 84000424 XER: 20040000
CFAR: c000000000c07a84 DAR: 0000000000000100 DSISR: 00080000 IRQMASK: 1
GPR00: c000000000c07a88 c000000072707c80 c000000001546300 c00000007be38a80
GPR04: c0000000726f0c00 0000000000000002 c00000007279c980 0000000000000100
GPR08: c000000001581b78 0000000080000001 0000000000000008 c00000007279c9b0
GPR12: 0000000000000000 c000000001730000 c000000000142558 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR24: c00000007be38a80 c000000000c002f4 0000000000000000 0000000000000000
GPR28: c000000072221a00 c0000000726c2600 c00000007be38a80 c00000007be38a80
NIP [c000000000097f88] __spin_yield+0x48/0xa0
LR [c000000000c07a88] __raw_spin_lock+0xb8/0xc0
Call Trace:
[c000000072707c80] [c000000072221a00] 0xc000000072221a00 (unreliable)
[c000000072707cb0] [c000000000bffb0c] __schedule+0xbc/0x850
[c000000072707d70] [c000000000c002f4] schedule+0x54/0x130
[c000000072707da0] [c0000000001427dc] kthreadd+0x28c/0x2b0
[c000000072707e20] [c00000000000c1cc] ret_from_kernel_thread+0x5c/0x70
Instruction dump:
4d9e0020 552a043e 210a07ff 79080fe0 0b080000 3d020004 3908b878 794a1f24
e8e80000 7ce7502a e8e70000 38e70100 <7ca03c2c> 70a70001 78a50020 4d820020
---[ end trace 474d6b2b8fc5cb7e ]---
Fixes: 499dcd41378e ("powerpc/64s: Allocate LPPACAs individually")
Signed-off-by: Christopher M. Riedl <cmr@informatik.wtf>
[mpe: Reword change log a bit]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190813031314.1828-4-cmr@informatik.wtf