On 26/02/18 21:12, Matthew Wilcox wrote: [...] > panic() halts the kernel > BUG_ON() kills the thread > WARN_ON() just prints messages > > Now, if we're at boot time and we're still executing code from the init > thread, killing init is equivalent to halting the kernel. > > The question is, what is appropriate for test modules? I would say > WARN_ON is not appropriate because people ignore warnings. BUG_ON is > reasonable for development. panic() is probably not. Ok, so I can leave WARN_ON() in the libraries, and keep the more restrictive BUG_ON() for the self test, which is optional for both genalloc and pmalloc. > Also, calling BUG_ON while holding a lock is not a good idea; if anything > needs to acquire that lock to shut down in a reasonable fashion, it's > going to hang. > > And there's no need to do something like BUG_ON(!foo); foo->wibble = 1; > Dereferencing a NULL pointer already produces a nice informative splat. > In general, we assume other parts of the kernel are sane and if they pass > us a NULL pool, it's no good returning -EINVAL, we may as well just oops > and let somebody else debug it. Great, that makes the code even simpler. -- igor -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
