Messages in this thread | | | From | "Fabio M. De Francesco" <> | Subject | Re: [PATCH] mm/highmem: VM_BUG_ON() if offset + len > PAGE_SIZE | Date | Tue, 26 Apr 2022 22:19:57 +0200 |
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On martedì 26 aprile 2022 21:34:12 CEST Andrew Morton wrote: > On Tue, 26 Apr 2022 21:30:20 +0200 "Fabio M. De Francesco" <fmdefrancesco@gmail.com> wrote: > > > Add VM_BUG_ON() bounds checking to make sure that, if "offset + len> > > PAGE_SIZE", memset() does not corrupt data in adjacent pages. > > > > hm, why? To match all the other functions in there? > > I suppose that's logical. Or we could just delete all the other > VM_BUG_ON()s. Have any of them proven to be at all useful? > I am not so sure about it being so useful. I just noted that memzero_page() is the only function of that family that is implemented with no VM_BUG_ON(). I have no actual proofs of usefulness :(
This is why yesterday I sent an "RFC Patch" (please see https://lore.kernel.org/lkml/20220424104806.25396-1-fmdefrancesco@gmail.com/
Soon after sending it I thought that VM_WARN_ON_ONCE() could have been better suited, but Ira Weiny wrote to use VM_BUG_ON() for consistency.
Now I could either delete all other VM_BUG_ON() or replace them with VM_WARN_ON_ONCE() (or some other macro).
Ah, a third solution might be to leave highmem.h as it is now :)
What do you prefer?
Thanks,
Fabio
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