On Thu, Apr 29, 2010 at 5:32 PM, Mel Gorman <mel@xxxxxxxxx> wrote: > From: Rik van Riel <riel@xxxxxxxxxx> > > Take all the locks for all the anon_vmas in anon_vma_lock, this properly > excludes migration and the transparent hugepage code from VMA changes done > by mmap/munmap/mprotect/expand_stack/etc... > > Unfortunately, this requires adding a new lock (mm->anon_vma_chain_lock), > otherwise we have an unavoidable lock ordering conflict. This changes the > locking rules for the "same_vma" list to be either mm->mmap_sem for write, > or mm->mmap_sem for read plus the new mm->anon_vma_chain lock. This limits > the place where the new lock is taken to 2 locations - anon_vma_prepare and > expand_downwards. > > Document the locking rules for the same_vma list in the anon_vma_chain and > remove the anon_vma_lock call from expand_upwards, which does not need it. > > Signed-off-by: Rik van Riel <riel@xxxxxxxxxx> Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx> I like this one. Although it try to lock the number of anon_vmas attached to a VMA , it's small so latency couldn't be big. :) It's height problem not width problem of tree. :) Thanks, Rik. -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href