On Wed, Jun 18, 2025 at 07:28:16PM +0530, Dev Jain wrote:
On 18/06/25 5:27 pm, Lorenzo Stoakes wrote:
On Wed, Jun 18, 2025 at 05:15:50PM +0530, Dev Jain wrote: Are you accounting for sys.max_map_count? If not, then you'll be hitting that first.
run_vmtests.sh will run the test in overcommit mode so that won't be an issue.
Umm, what? You mean overcommit all mode, and that has no bearing on the max mapping count check.
In do_mmap():
/* Too many mappings? */ if (mm->map_count > sysctl_max_map_count) return -ENOMEM;
As well as numerous other checks in mm/vma.c.
I'm not sure why an overcommit toggle is even necessary when you could use MAP_NORESERVE or simply map PROT_NONE to avoid the OVERCOMMIT_GUESS limits?
I'm pretty confused as to what this test is really achieving honestly. This isn't a useful way of asserting mmap() behaviour as far as I can tell.