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 <[email protected]>
Closes:
https://lore.kernel.org/all/[email protected]/
Signed-off-by: Shrikanth Hegde <[email protected]>
---
I was able to reproduce this issue consistently, and confirm with this
patch, reproted issue is fixed. Hence,
Tested-by: Venkat Rao Bagalkote <[email protected]>
Regards,
Venkat.
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/[email protected]/
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)
