On Tue, Apr 28, 2015 at 9:43 AM, Michal Hocko <mhocko@xxxxxxx> wrote: > > Hmm, no other thread has the address from the current mmap call except > for MAP_FIXED (more on that below). With things like opportunistic SIGSEGV handlers that map/unmap things as the user takes faults, that's actually not at all guaranteed. Yeah, it's unusual, but I've seen it, with threaded applications where people play games with user-space memory management, and do "demand allocation" with mmap() in response to signals. Admittedly we already do bad things in mmap(MAP_FIXED) for that case, since we dropped the vm lock. But at least it shouldn't be any worse than a thread speculatively touching the pages.. Linus -- 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>