Hi On Tue, Jun 17, 2014 at 6:20 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: > Can you summarize why holes can't be reliably backed by the zero page? To answer this, I will quote Hugh from "PATCH v2 1/3": > We do already use the ZERO_PAGE instead of allocating when it's a > simple read; and on the face of it, we could extend that to mmap > once the file is sealed. But I am rather afraid to do so - for > many years there was an mmap /dev/zero case which did that, but > it was an easily forgotten case which caught us out at least > once, so I'm reluctant to reintroduce it now for sealing. > > Anyway, I don't expect you to resolve the issue of sealed holes: > that's very much my territory, to give you support on. Holes can be avoided with a simple fallocate(). I don't understand why I should make SEAL_WRITE do the fallocate for the caller. During the discussion of memfd_create() I was told to drop the "size" parameter, because it is redundant. I don't see how this implicit fallocate() does not fall into the same category? Thanks David -- 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>