(2012/04/02 21:04), Aneesh Kumar K.V wrote: > > Hi, > > I started looking at unmap_hugepage_range. unmap_hugepage_range takes > i_mmap_mutex. But then the same lock is also taken higher up in the > stack. ie via the below chain > > unmap_mapping_range (i_mmap_mutex) > -> unmap_mapping_range_tree > -> unmap_mapping_range_vma > -> zap_page_range_single > -> unmap_single_vma > -> unmap_hugepage_range (i_mmap_mutex) > why not deadlock ? > But there are other code path that doesn't take i_mmap_mutex. For ex: > -> madvise_dontneed > -> zap_page_range > -> unmap_vmas > -> unmap_single_vma > -> unmap_page_range > > IIUC, DONTNEED will not change vma layout...so it doesn't require i_mmap_mutex. Thanks, -Kame -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>