Messages in this thread | | | Date | Tue, 5 Apr 2005 12:53:27 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: crash in entry.S restore_all, 2.6.12-rc2, x86, PAGEALLOC |
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On Tue, 5 Apr 2005, Stas Sergeev wrote: > > > So I'd actually prefer to get that mystery explained.. > IIRC if the interrupt doesn't do the CPL > switch, the interrupt gate doesn't save > the stack, and so there may not be the > full "struct pt_regs" when the kernel > thread is interrupted.
Yes. But how do you have _such_ an empty stack when the interrupt comes in? See what I mean? IOW, that requires that the kernel stack would have only two words on it when the interrupt happens. How?
It may be a 4kB stack issue or something. Does this happen only with CONFIG_4KSTACKS, and just after a stack switch to an irq stack, for example?
So I definitely think the "bug" is in your optimization, I just think it should be a valid optimization and we should just make sure our kernel stack is never _so_ empty that "struct pt_regs" is not safe to dereference.
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