Re: [PATCH -v2] rmap: make anon_vma_prepare link in all the anon_vmasof a mergeable VMA

From: Rik van Riel
Date: Wed Apr 07 2010 - 17:53:55 EST


On 04/07/2010 05:19 PM, Linus Torvalds wrote:

Comments?

I remember there being an "unfixable" spot with this
approach when I originally wrote the new anon_vma
linking code.

However, I can't for the life of me find that spot.
I am starting to believe I made it fixable as a side
effect of one of the changes I made :)

One of the issues with your patch is that anon_vma_prepare
can fail and this patch ignores its return value.

Having anon_vma-prepare fail after an mremap or mprotect
might result in messing up the VMAs of a process, or having
to undo the VMA changes that were made.

In fact, this may be the problem I was running into - not
wanting to add even more complex error paths to the vma
shuffling code.
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