Re: [PATCH v2] powerpc/entry: Disable interrupts before irqentry_exit
From: Venkat Rao Bagalkote <hidden>
Date: 2026-06-05 07:42:56
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On 03/06/26 6:40 pm, Shrikanth Hegde wrote:
Venkat reported a panic on powerpc-next tree where GENERIC_ENTRY has
been enabled.
kernel BUG at kernel/sched/core.c:7512!
NIP preempt_schedule_irq+0x44/0x118
LR dynamic_irqentry_exit_cond_resched+0x40/0x1a4
Call Trace:
dynamic_irqentry_exit_cond_resched+0x40/0x1a4
do_page_fault+0xc0/0x104
data_access_common_virt+0x210/0x220
This happens since __do_page_fault ends up enabling the interrupts and
it could take significant time such that need_resched could be set. This
leads to schedule call in irqentry_exit leading to the bug.
There are many such irq handlers which enables the interrupts.
Fix it by disabling the irq before calling irqentry_exit. The same
pattern exists today in interrupt_exit_kernel_prepare.
Fixes: bee25f97ad24 ("powerpc: Enable GENERIC_ENTRY feature")
Reported-by: Venkat Rao Bagalkote <redacted>
Closes: https://lore.kernel.org/all/7904105b-9dfa-4efd-a5ef-bc0276ed255d@linux.ibm.com/ (local)
Signed-off-by: Shrikanth Hegde <redacted>
---I was able to reproduce this issue consistently, and confirm with this patch, reproted issue is fixed. Hence, Tested-by: Venkat Rao Bagalkote <redacted> Regards, Venkat.
quoted hunk ↗ jump to hunk
This applies on top on powerpc/next tree. base: 6ed60999d33d '("powerpc: Remove unused functions")' v1->v2: Leave those BUG_ON alone since they are tracking the register state of userspace (Peter Zijlstra) v1: https://lore.kernel.org/all/20260603095521.198267-1-sshegde@linux.ibm.com/ (local) arch/powerpc/include/asm/entry-common.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)diff --git a/arch/powerpc/include/asm/entry-common.h b/arch/powerpc/include/asm/entry-common.h index de5601282755..fc636c42e89a 100644 --- a/arch/powerpc/include/asm/entry-common.h +++ b/arch/powerpc/include/asm/entry-common.h@@ -260,9 +260,10 @@ static inline void arch_interrupt_exit_prepare(struct pt_regs *regs) * AMR can only have been unlocked if we interrupted the kernel. */ kuap_assert_locked(); - - local_irq_disable(); } + + /* irqentry_exit expects to be called with interrupts disabled */ + local_irq_disable(); } static inline void arch_interrupt_async_enter_prepare(struct pt_regs *regs)