On Thu, Jun 05, 2014 at 11:56:58AM -0400, Dave Jones wrote: > On Thu, Jun 05, 2014 at 06:40:36AM +0200, Michael Kerrisk (man-pages) wrote: > > On 06/05/2014 01:31 AM, Dave Jones wrote: > > > I just noticed that trinity was freaking out in places when mmap was > > > returning zero. This surprised me, because I had the mmap_min_addr > > > sysctl set to 64k, so it wasn't a MAP_FIXED mapping that did it. > > > > > > There's no mention of this return value in the man page, so I dug > > > into the kernel code, and it appears that we do.. > > > > > > sys_mmap > > > vm_mmap_pgoff > > > security_mmap_file > > > ima_file_mmap <- returns 0 if not PROT_EXEC > > > > > > and then the 0 gets propagated up as a retval all the way to userspace. > > I just realised that this affects even kernels with CONFIG_IMA unset, > because there we just do 'return 0' unconditionally. > > Also, it appears that kernels with CONFIG_SECURITY unset will also > return a zero for the same reason. Hang on, I was misreading that whole security_mmap_file ret handling code. There's something else at work here. I'll dig and get a reproducer. Dave -- 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>