Messages in this thread | | | Date | Wed, 7 May 2008 18:39:48 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH 08 of 11] anon-vma-rwsem |
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On Wed, 7 May 2008, Christoph Lameter wrote: > > > (That said, we're not running out of vm flags yet, and if we were, we > > could just add another word. We're already wasting that space right now on > > 64-bit by calling it "unsigned long"). > > We sure have enough flags.
Oh, btw, I was wrong - we wouldn't want to mark the vma's (they are unique), we need to mark the address spaces/anonvma's. So the flag would need to be in the "struct anon_vma" (and struct address_space), not in the vma itself. My bad. So the flag wouldn't be one of the VM_xyzzy flags, and would require adding a new field to "struct anon_vma()"
And related to that brain-fart of mine, that obviously also means that yes, the locking has to be stronger than "mm->mmap_sem" held for writing, so yeah, it would have be a separate global spinlock (or perhaps a blocking lock if you have some reason to protect anything else with this too).
Linus
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