On Thu, Apr 29, 2010 at 09:28:25AM +0900, Minchan Kim wrote: > On Thu, Apr 29, 2010 at 5:57 AM, Rik van Riel <riel@xxxxxxxxxx> wrote: > > 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> > > This patch makes things simple. So I like this. Agreed. > Actually, I wanted this all-at-once locks approach. > But I was worried about that how the patch affects AIM 7 workload > which is cause of anon_vma_chain about scalability by Rik. I had similar concerns. I'm surprised how it worked out. > But now Rik himself is sending the patch. So I assume the patch > couldn't decrease scalability of the workload heavily. > > Let's wait result of test if Rik doesn't have a problem of AIM7. > -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>