On Thu, Aug 10, 2017 at 3:05 PM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: >> Too late for that. VM_DONTFORK is already implemented >> through MADV_DONTFORK & MADV_DOFORK, in a way that is >> very similar to the MADV_WIPEONFORK from these patches. > > Yeah, those two seem to be breaking the "madvise as an advise" semantic as > well but that doesn't mean we should follow that pattern any further. I would imagine that many of the crypto applications using MADV_WIPEONFORK will also be using MADV_DONTDUMP. In cases where it's for protecting secret keys, I'd like to use both in my code, for example. Though that doesn't really help decide this. There is also at least one case for being able to turn WIPEONFORK on/off with an existing page; a process that uses privilege separation often goes through the following flow: 1. [ Access privileged keys as a power user and initialize memory ] 2. [ Fork a child process that actually does the work ] 3. [ Child drops privileges and uses the memory to do work ] 4. [ Parent hangs around to re-spawn a child if it crashes ] In that mode it would be convenient to be able to mark the memory as WIPEONFORK in the child, but not the parent. -- Colm -- 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>
