panic: add TAINT_SOFTLOCKUP

This taint flag will be set if the system has ever entered a softlockup
state.  Similar to TAINT_WARN it is useful to know whether or not the
system has been in a softlockup state when debugging.

[akpm@linux-foundation.org: apply the taint before calling panic()]
Signed-off-by: Josh Hunt <johunt@akamai.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index c14374e..f79eb96 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -826,6 +826,7 @@
 4096 - An out-of-tree module has been loaded.
 8192 - An unsigned module has been loaded in a kernel supporting module
        signature.
+16384 - A soft lockup has previously occurred on the system.
 
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