On Fri 28-08-15 16:31:30, Michal Hocko wrote: > On Wed 26-08-15 14:24:23, Eric B Munson wrote: > > The previous patch introduced a flag that specified pages in a VMA > > should be placed on the unevictable LRU, but they should not be made > > present when the area is created. This patch adds the ability to set > > this state via the new mlock system calls. > > > > We add MLOCK_ONFAULT for mlock2 and MCL_ONFAULT for mlockall. > > MLOCK_ONFAULT will set the VM_LOCKONFAULT modifier for VM_LOCKED. > > MCL_ONFAULT should be used as a modifier to the two other mlockall > > flags. When used with MCL_CURRENT, all current mappings will be marked > > with VM_LOCKED | VM_LOCKONFAULT. When used with MCL_FUTURE, the > > mm->def_flags will be marked with VM_LOCKED | VM_LOCKONFAULT. When used > > with both MCL_CURRENT and MCL_FUTURE, all current mappings and > > mm->def_flags will be marked with VM_LOCKED | VM_LOCKONFAULT. > > > > Prior to this patch, mlockall() will unconditionally clear the > > mm->def_flags any time it is called without MCL_FUTURE. This behavior > > is maintained after adding MCL_ONFAULT. If a call to > > mlockall(MCL_FUTURE) is followed by mlockall(MCL_CURRENT), the > > mm->def_flags will be cleared and new VMAs will be unlocked. This > > remains true with or without MCL_ONFAULT in either mlockall() > > invocation. Btw. I think we really want a man page for this new mlock call. -- Michal Hocko SUSE Labs
