2014-05-01 6:19 GMT+09:00, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>: > On Tue, 29 Apr 2014 11:53:10 +0900 Daeseok Youn <daeseok.youn@xxxxxxxxx> > wrote: > >> "dev" cannot be NULL because it is already checked before >> calling dma_pool_create(). >> >> Signed-off-by: Daeseok Youn <daeseok.youn@xxxxxxxxx> >> --- >> If dev can be NULL, it has NULL deferencing when kmalloc_node() >> is called after enabling CONFIG_NUMA. > > hm, this is unclear. > > The code which handles the dev==NULL case was obviously put there > deliberately, presumably with the intention of permitting drivers to > call dma_pool_create() without a device*. This code is very old. > > A lot of drivers call dma_pool_create() (I doubt if you audited all of > them!) and perhaps there are some which use this feature and have never > been run on NUMA hardware. Yes.. I didn't check all of callers.. sorry about that. Some drivers are checked. > > I think I'll apply the patch anyway because such drivers (if they > exist) probably need some attending to. > > I rewrote the changelog thusly: > > > : "dev" cannot be NULL because it is already checked before calling > : dma_pool_create(). > : > : If dev ever was NULL, the code would oops in dev_to_node() after enabling > : CONFIG_NUMA. > : > : It is possible that some driver is using dev==NULL and has never been run > : on a NUMA machine. Such a driver is probably outdated, possibly buggy > and > : will need some attention if it starts triggering NULL derefs. > > Ok. Thanks for kind explanation. Regards, Daeseok Youn -- 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>