On Nov 27, 2015, at 19:09, Petr Mladek <pmla...@suse.com> wrote:
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 <pmla...@suse.com> --- 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)]; };
why not define like this:
union { struct {atomic_t len; struct irq_work work; } unsigned char buffer[PAGE_SIZE * 2] ; }
we can make sure the union is 2 PAGE_SIZE .
Thanks
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