From 5dbe0af47f8a8f968bac2991c3ec974c6e3eaabc Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Sat, 28 May 2011 13:17:04 -0700 Subject: [PATCH] mm: fix kernel BUG at mm/rmap.c:1017! I've hit the "address >= vma->vm_end" check in do_page_add_anon_rmap() just once. The stack showed khugepaged allocation trying to compact pages: the call to page_add_anon_rmap() coming from remove_migration_pte(). That path holds anon_vma lock, but does not hold mmap_sem: it can therefore race with a split_vma(), and in commit 5f70b962ccc2 "mmap: avoid unnecessary anon_vma lock" we just took away the anon_vma lock protection when adjusting vma->vm_end. I don't think that particular BUG_ON ever caught anything interesting, so better replace it by a comment, than reinstate the anon_vma locking. Signed-off-by: Hugh Dickins Signed-off-by: Linus Torvalds --- Reading git-format-patch failed