[PATCH v2 5/5] printk/nmi: Increase the size of the temporary buffer
From: yalin wang <hidden>
Date: 2015-11-30 16:42:21
Also in:
linux-mips, linux-sh, linuxppc-dev, lkml, sparclinux
quoted hunk ↗ jump to hunk
On Nov 27, 2015, at 19:09, Petr Mladek [off-list ref] 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 <pmladek@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