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On 11/18/06, Hugh Dickins <hugh@veritas.com> wrote: > On Fri, 17 Nov 2006, Francis Moreau wrote: > > On Fri, 2006-11-17 at 14:12 +0000, moreau francis wrote: > > > Peter Zijlstra wrote: > > > > > > The new object is the one allocated using: > > > new = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); > > > > Of course but at this point the choice of the new VMA is already made > > by the caller. So in our case do_munmap() decided that B is the new > > one as you said. But I still don't see why... > > split_vma decides which address range will use the newly allocated > vm_area_struct in such a way as to suit its own convenience, and again I don't agree. I would say that do_munmap() decides which address range will use the new allocated vma object. split_vma() get this information through its parameter named "new_below". > > > > And as I said previously it will end up by calling consecutively: > > > > vma->vm_ops->open(B) > > vma->vm_ops->close(B) > > You are attaching too much significance to the current address > of the vma which is passed to your driver in open and close. > As mmap.c splits and merges vmas, in response to system calls > unmapping and mapping, those addresses will change. > > The important thing is the info contained within the vma: perhaps > your underlying complaint is that your driver is not getting as > much info as it wants about what's happening? > not really. I'm not writing a real driver. I just try to understand how vma things work in Linux. Therefore I just wrote a dumb driver which has modified vma open/close method in order to detect how these method are called. I end up to see "open(B), close(B)" sequence when unmapping a part of the dumb device that I found strange. I think that "open(A') close(B)" can give more information to the driver and reflect that B is unmapped and A' is still mapped and becomes the new mapped area. But it's may be just me... thanks Francis - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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