On Tue, Feb 25, 2025 at 07:31:01PM -0800, Linus Torvalds wrote: > > I don't understand why the dirty bit needs to be saved. At least in > > the vfree() case, we're freeing the memory so any unflushed writes to > > it may as well disappear. But I don't know all the circumstances in > > which these functions are called. > > I'm not saying that it needs to be saved. > > But I *am* saying that it needs to be explained why dropping it is fine. > > And I am also saying that your explanation for why it should be > cleared makes no sense, since two out of three cases also cleared > _PAGE_PRESENT, at which point the whole shadow stack issue is > completely irrelevant. > > So please explain *why* clearing PAGE_DIRTY is ok. Don't bring up > issues like the shadow stack setting that is irrelevant for at least > two of the cases that you changed. > > If all of these are purely used for vmalloc() or direct mappings, then > *that* is a valid explanation ("we don't care about dirty bits on > kernel mappings"), for example. I think the entire point of this file is to manipulate kernel mappings.
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