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SubjectRe: [linux-next][regression] [PATCH] percpu: add preemption checks to __this_cpu ops
On 03/18/2014 11:37 PM, Andrew Morton wrote:> On Tue, 18 Mar 2014 10:54:06 -0500 (CDT) Christoph Lameter <> wrote:
>> On Tue, 18 Mar 2014, Grygorii Strashko wrote:
>>> Any way, I can boot and console works fine with your change :)
>>> Thanks.
>> Ok here is the properly formatted patch:
>> Subject: preemption_checks: Avoid snprintf before checking error conditions
>> snprintf can cause hangs.
> This is weird. How the heck can snprintf() fail if called too early?
> All it does is shuffle chars around in memory. The only external
> dependency I'm seeing is a WARN_ON() which presumably didn't trigger
> anyway.
> I'm suspecting a misdiagnosis here. Otherwise, we seriously need to
> fix snprintf(), not work around it!

Not sure I can run debugger fast :(, but I'll try.

> Also, what does "before checking error conditions" refer to? Does this
> mean you know why snprintf() failed??

Just an assumption, May be the problem here not in snprintf, but in stack.
Looks like if I reduce stack usage the issue is gone:
char text[10];

>> Move the string processing into the function
>> so that the string operations only occur when necessary after the
>> conditions have been checked.
>> Tested-by: Grygorii Strashko <>
> Grygorii, thanks for testing linux-next on unusual machines - it's most
> helpful.


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