Messages in this thread | | | Subject | Re: [RFC][PATCH] mm: Remove ZERO_SIZE_PTR. | From | Tetsuo Handa <> | Date | Sat, 27 Feb 2010 09:59:49 +0900 |
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Christoph Lameter wrote: > On Fri, 26 Feb 2010, Tetsuo Handa wrote: > > > Everybody should check for ptr != NULL, and most callers are actually checking > > for ptr != NULL. But nobody is checking for ptr != ZERO_SIZE_PTR. > > That is so intentionally because some kernel subsystem can do a zero size > allocation. > So, not only users *can* do zero size allocation, but also there *are* users who are intentionally doing zero size allocation. Then, we can't remove ZERO_SIZE_PTR.
> > Yes, this is the fault of caller. But ZERO_SIZE_PTR is too small value to > > distinguish "NULL pointer dereference" and "ZERO_SIZE_PTR dereference" because > > address printed by oops message can easily exceed ZERO_SIZE_PTR when > > "struct foo" is large. > > Correct.
Maybe PAGE_SIZE / 2 is better than 16?
Thanks.
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