On 07/23/2012 12:04 AM, Hugh Dickins wrote:
Please don't be upset if I say that I don't like either of your patches. Mainly for obvious reasons - I don't like Mel's because anything with trylock retries and nested spinlocks worries me before I can even start to think about it; and I don't like Michal's for the same reason as Mel, that it spreads more change around in common paths than we would like.
I have a naive question. In huge_pmd_share, we protect ourselves by taking the mapping->i_mmap_mutex. Is there any reason we could not take the i_mmap_mutex in the huge_pmd_unshare path? I see that hugetlb_change_protection already takes that lock. Is there something preventing __unmap_hugepage_range from also taking mapping->i_mmap_mutex? That way the sharing and the unsharing code are protected by the same, per shm segment, lock. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>