On Tue, Jan 26, 2016 at 04:36:11PM -0800, David Rientjes wrote: > On Wed, 27 Jan 2016, Joonsoo Kim wrote: > > > > I'd agree if CONFIG_DEBUG_PAGEALLOC only did anything when > > > debug_pagealloc_enabled() is true, but that doesn't seem to be the case. > > > When CONFIG_DEBUG_SLAB is enabled, for instance, CONFIG_DEBUG_PAGEALLOC > > > also enables stackinfo storing and poisoning and it's not guarded by > > > debug_pagealloc_enabled(). > > > > > > It seems like CONFIG_DEBUG_PAGEALLOC enables debugging functionality > > > outside the scope of the debug_pagealloc=on kernel parameter, so > > > DEBUG_PAGEALLOC(disabled) actually does mean something. > > > > Hello, David. > > > > I tried to fix CONFIG_DEBUG_SLAB case on 04/16 of following patchset. > > > > http://thread.gmane.org/gmane.linux.kernel.mm/144527 > > > > I found that there are more sites to fix but not so many. > > We can do it. > > > > For the slab case, sure, this can be fixed, but there is other code that > uses CONFIG_DEBUG_PAGEALLOC to suggest debugging is always enabled and is > indifferent to debug_pagealloc_enabled(). I find this in powerpc and > sparc arch code as well as generic vmalloc code. Yes, I also found it. > > If we can convert existing users that only check for > CONFIG_DEBUG_PAGEALLOC to rather check for debug_pagealloc_enabled() and > agree that it is only enabled for debug_pagealloc=on, then this would seem > fine. However, I think we should at least consult with those users before > removing an artifact from the kernel log that could be useful in debugging > why a particular BUG() happened. Yes, at least, non-architecture dependent code (vmalloc, SLAB, SLUB) should be changed first. If Christian doesn't mind, I will try to fix above 3 things. Thanks. -- 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>