Sayali Patil 31467b2382 powerpc/time: Remove redundant preempt_disable|enable() calls from arch_irq_work_raise() ... A kernel panic is observed when handling machine check exceptions from real mode. BUG: Unable to handle kernel data access on read at 0xc00000006be21300 Oops: Kernel access of bad area, sig: 11 [#1] MSR: 8000000000001003 <SF,ME,RI,LE> CR: 88222248 XER: 00000005 CFAR: c00000000003ffc4 DAR: c00000006be21300 DSISR: 40000000 IRQMASK: 0 NIP [c000000000029e40] arch_irq_work_raise+0x10/0x70 LR [c00000000003ffc8] machine_check_queue_event+0xa8/0x150 Call Trace: [c0000000179d3c70] [c00000000003ff64] machine_check_queue_event+0x44/0x150 [c0000000179d3d30] [c0000000000084e0] machine_check_early_common+0x1f0/0x2c0 The crash occurs because arch_irq_work_raise() calls preempt_disable() from machine check exception (MCE) handlers running in real mode. In this context, accessing the preempt_count can fault, leading to the panic. The preempt_disable()/preempt_enable() pair in arch_irq_work_raise() was originally added by commit 0fe1ac48be ("powerpc/perf_event: Fix oops due to perf_event_do_pending call") to avoid races while raising irq work from exception context. Later, commit 471ba0e686 ("irq_work: Do not raise an IPI when queueing work on the local CPU") added preemption protection in irq_work_queue() path, while commit 20b876918c ("irq_work: Use per cpu atomics instead of regular atomics") added equivalent protection in irq_work_queue_on() before reaching arch_irq_work_raise(): irq_work_queue() / irq_work_queue_on() -> preempt_disable() -> __irq_work_queue_local() -> irq_work_raise() -> arch_irq_work_raise() As a result, callers other than mce_irq_work_raise() already execute with preemption disabled, making the additional preempt_disable()/preempt_enable() pair in arch_irq_work_raise() redundant. The arch_irq_work_raise() function executes in NMI context when called from MCE handler. Hence we will not be preempted or scheduled out since we are in NMI context with MSR[EE]=0. Therefore, it is safe to remove the preempt_disable()/preempt_enable() calls from here. Remove it to avoid accessing preempt_count from real mode context. Fixes: cc15ff3275 ("powerpc/mce: Avoid using irq_work_queue() in realmode") Suggested-by: Mahesh Salgaonkar <mahesh@linux.ibm.com> Acked-by: Shrikanth Hegde <sshegde@linux.ibm.com> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com> [Maddy: Fixed the commit title] Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com> Link: https://patch.msgid.link/20260513081413.222490-1-sayalip@linux.ibm.com		2026-05-14 11:15:26 +05:30
..
boot	powerpc updates for 7.1	2026-04-14 17:10:15 -07:00
configs	powerpc/g5: Enable all windfarms by default	2026-05-12 11:48:01 +05:30
crypto	lib/crypto: powerpc/ghash: Migrate optimized code into library	2026-03-23 16:44:29 -07:00
include	powerpc/powermac: Remove pmac_low_i2c_{lock,unlock}()	2026-05-12 11:50:09 +05:30
kernel	powerpc/time: Remove redundant preempt_disable|enable() calls from arch_irq_work_raise()	2026-05-14 11:15:26 +05:30
kexec	powerpc/kdump: fix KASAN sanitization flag for core_$(BITS).o	2026-05-06 07:31:27 +05:30
kvm	KVM: PPC: remove hugetlb.h inclusion	2026-04-05 13:53:23 -07:00
lib	powerpc/vmx: avoid KASAN instrumentation in enter_vmx_ops() for kexec	2026-05-06 07:31:28 +05:30
math-emu
mm	mm.git review status for linus..mm-stable	2026-04-15 12:59:16 -07:00
net	bpf: Pass bpf_verifier_env to JIT	2026-04-16 07:03:40 -07:00
perf	powerpc/hv-gpci: fix preempt count leak in sysfs show paths	2026-05-12 11:51:17 +05:30
platforms	powerpc/powermac: Remove pmac_low_i2c_{lock,unlock}()	2026-05-12 11:50:09 +05:30
purgatory	Makefile: remove redundant tool coverage variables	2024-05-14 23:35:48 +09:00
sysdev	powerpc updates for 7.1	2026-04-14 17:10:15 -07:00
tools	powerpc64/ftrace: fix OOL stub count with clang	2026-03-07 16:02:25 +05:30
xmon	powerpc/xmon: replace sizeof calculations with ARRAY_SIZE macro	2025-09-01 13:40:46 +05:30
Kbuild	powerpc64/ftrace: Move ftrace sequence out of line	2024-10-31 11:00:54 +11:00
Kconfig	integrity-v7.1	2026-04-17 15:42:01 -07:00
Kconfig.debug	powerpc: fix dead default for GUEST_STATE_BUFFER_TEST	2026-05-12 11:50:52 +05:30
Makefile	kbuild: Add missing $(objtree) prefix to powerpc crtsavres.o artifact	2025-09-01 13:41:57 +05:30
Makefile.postlink	powerpc/ftrace: Add a postlink script to validate function tracer	2024-10-31 11:00:54 +11:00