On Wed, 2012-04-18 at 21:28 +0800, Cong Wang wrote: > On 04/18/2012 05:27 PM, Li Zhong wrote: > > When reading the mmap codes, I found the checking of mm->map_count > > against sysctl_max_map_count is not consistent. At some places, ">" is > > used; at some other places, ">=" is used. > > > > This patch changes ">" to">=", so they are consistent, and makes sure > > the value is not greater (one more) than sysctl_max_map_count. > > > > Well, according to Documentation/sysctl/vm.txt, > > max_map_count: > > This file contains the maximum number of memory map areas a process > may have. [...] > > I think ->map_count == sysctl_max_map_count should be allowed, so using > '>' is correct. > Yes, I agree that ->map_count == sysctl_max_map_count should be allowed. However, with '>' used. The ->map_count could be sysctl_max_map_count+1. It could be seen with a simple program doing continuously mmaping of a file. ( Still it is possible, as stated in the comments of do_munmap code, if the VMA is going to be divided into two, the map_count could temporarily be sysctl_max_map_count+1, after the original vma split into two, and before one of the two vmas removed. ) -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>