[PATCH v2 5/5] printk/nmi: Increase the size of the temporary buffer

[Petr Mladek]

Testing has shown that the backtrace sometimes does not fit
into the 4kB temporary buffer that is used in NMI context.

The warnings are gone when I double the temporary buffer size.

Note that this problem existed even in the x86-specific
implementation that was added by the commit a9edc8809328
("x86/nmi: Perform a safe NMI stack trace on all CPUs").
Nobody noticed it because it did not print any warnings.

Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
---
 kernel/printk/nmi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/printk/nmi.c b/kernel/printk/nmi.c
index 8af1e4016719..6111644d5f01 100644
--- a/kernel/printk/nmi.c
+++ b/kernel/printk/nmi.c
@@ -42,7 +42,7 @@ atomic_t nmi_message_lost;
 struct nmi_seq_buf {
 	atomic_t		len;	/* length of written data */
 	struct irq_work		work;	/* IRQ work that flushes the buffer */
-	unsigned char		buffer[PAGE_SIZE - sizeof(atomic_t) -
+	unsigned char		buffer[2 * PAGE_SIZE - sizeof(atomic_t) -
 				       sizeof(struct irq_work)];
 };
 static DEFINE_PER_CPU(struct nmi_seq_buf, nmi_print_seq);
-- 
1.8.5.6

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