On Thu, Jul 07, 2016 at 10:28:12AM +0200, Michal Hocko wrote: > On Mon 04-07-16 00:17:55, Michael S. Tsirkin wrote: > > On Sun, Jul 03, 2016 at 06:47:23PM +0200, Oleg Nesterov wrote: > > > On 07/03, Michael S. Tsirkin wrote: > > > > > > > > On Sun, Jul 03, 2016 at 05:18:29PM +0200, Oleg Nesterov wrote: > > > > > > > > > > Well, we are going to kill all tasks which share this memory. I mean, ->mm. > > > > > If "sharing memory with another task" means, say, a file, then this memory > > > > > won't be unmapped (if shared). > > > > > > > > > > So let me ask again... Suppose, say, QEMU does VHOST_SET_OWNER and then we > > > > > unmap its (anonymous/non-shared) memory. Who else's memory can be corrupted? > > > > > > > > As you say, I mean anyone who shares memory with QEMU through a file. > > > > > > And in this case vhost_worker() reads the anonymous memory of QEMU process, > > > not the memory which can be shared with another task, correct? > > > > > > And if QEMU simply crashes, this can't affect anyone who shares memory with > > > QEMU through a file, yes? > > > > > > Oleg. > > > > Well no - the VM memory is not always anonymous memory. It can be an > > mmaped file. > > Just to make sure we are all at the same page. I guess the scenario is > as follows. The owner of the mm has ring and other statefull information > in the private memory but consumers living with their own mm consume > some data from a shared memory segments (e.g. files). The worker would > misinterpret statefull information (zeros rather than the original > content) and would copy invalid/corrupted data to the consumer. Am I > correct? > > -- > Michal Hocko > SUSE Labs Exactly. -- 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>