Re: PATCH [2.4.0test10]: Kiobuf#02, fault-in fix

"Stephen C. Tweedie" wrote:

Next part of the kiobuf diffs: fix the fact that handle_mm_fault
doesn't guarantee to complete the operation in all cases; doesn't
guarantee that the resulting pte is writable if write access was
requested; and doesn't pin the page against immediately being swapped
back out.

Dumb question time, if you don't mind.  :)  All code examples are from
mm/memory.c.

This seems to imply datain means 'read access':
	int datain = (rw == READ);

This seems to further imply datain means 'read access':
	if (((datain) && (!(vma->vm_flags & VM_WRITE))) ||

And then we pass 'datain' as the 'write_access' arg of handle_mm_fault:
	if (handle_mm_fault(current->mm, vma, ptr, datain) <= 0)

Further down in make_pages_present, there seems to be the opposite:
	write = (vma->vm_flags & VM_WRITE) != 0;
	[...]
	if (handle_mm_fault(mm, vma, addr, write) < 0)


So, why do we pass 'datain' as the 'write_access' arg of
handle_mm_fault? 
(and now in your 02-faultfix.diff patch, as the 'write' arg of
follow_page)

Regards,

	Jeff


-- 
Jeff Garzik             | Dinner is ready when
Building 1024           | the smoke alarm goes off.
MandrakeSoft            |	-/usr/games/fortune
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