https://bugzilla.kernel.org/show_bug.cgi?id=97511 Bug ID: 97511 Summary: Document vm.overcommit_memory=2 interaction with mmap/mprotect/madvise Product: Documentation Version: unspecified Hardware: All OS: Linux Status: NEW Severity: normal Priority: P1 Component: man-pages Assignee: documentation_man-pages@xxxxxxxxxxxxxxxxxxxx Reporter: fweimer@xxxxxxxxxx Regression: No For mmap and MAP_NORESERVE: In vm.overcommit_memory=2, private mappings still count towards the commit limit, despite what the flag name might imply. For mmap and PROT_NONE: Mappings created with this protection flag do not count towards the commit limit in vm.overcommit_memory=2 mode. mprotect can subsequently be used to change the flags of (parts of) the mapping, to allocate memory as needed, at which point mprotect may fail with ENOMEM. For mprotect and madvise: mprotect/madvise cannot be used to mark a previously allocated memory region as unallocated, but reserved, and not have it count towards the vm.overcommit_memory=2 limit. Instead, use mmap with MAP_FIXED and a PROT_NONE memory area, which will mark the region as unused. -- You are receiving this mail because: You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
