Messages in this thread | | | Subject | Re: Process-shared futexes on hugepages puts the kernel in an infinite loop in 2.6.32.11; is this fixed now? | From | Peter Zijlstra <> | Date | Mon, 19 Apr 2010 18:18:48 +0200 |
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On Mon, 2010-04-19 at 18:11 +0200, Andrea Arcangeli wrote: > On Mon, Apr 19, 2010 at 05:45:05PM +0200, Peter Zijlstra wrote: > > Wouldn't a longer poison be more recognisable? Also, shouldn't this use > > POISON_POINTER_DELTA? > > > > Something like: > > > > #define HUGETBL_POISON ((void *) 0x00300300 + POISON_POINTER_DELTA) > > > > 0x2e5 isn't that high, I've had actual derefs in that range. > > The default at kernel config time sets only 4k as unmapped (I think > it's a very bad default for 64bit archs), so above 4k userland can map > it and you can have actual derefs with 0x00300300 but not with Mel's > preferred <0x1000 address. So the address must be <0x1000.
Well, most poison values have that problem and still we have them. Also on 64bit machines you can use POISON_POINTER_DELTA to map it outside the virtual address range.
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