On Tue, May 16, 2023 at 06:38:30PM -0400, Liam R. Howlett wrote: > > It seems to me what you're trying to explain is we shouldn't handle any > > split in vma_merge() so we should move cases 4 & 5 out of vma_merge(). If > > we split first then merge, cases 4 & 5 will become case 2 & 3 after split. > > We don't split in case 4 or 5 - we adjust the existing VMA limits. We > don't actually handle any splits in vma_merge(). I think splitting > first would change 4 & 5 to 7 & 8? 2 & 3 would require a split and > munmap, right? Right, I referenced to the wrong numbers.. 2 & 3 are when CUR (CCCC) is empty and newly mapped in, if split happened it means CUR (CCCC) exists which is 7 & 8 correspondingly. > > > My question would be: if it worked perfect in the past few years and it > > looks all good enough, why bother.. > > I suspect, but it's not clear (like all of this), that the other > arguments to vma_merge() is ruling out this potential hazard I thought > existed. Some more elaborations on this one would be appreciated. Thanks, -- Peter Xu
