On Sun, Nov 21, 2010 at 08:30:24AM -0500, Ted Ts'o wrote: > On Sun, Nov 21, 2010 at 07:26:11PM +0800, Arun Bhanu wrote: > > I saw this in kernel log messages while testing 2.6.37-rc2. I think it > > appeared while mounting an external hard-disk. I can't seem to > > reproduce it. > > I could be wrong but this looks like it's a bug in mm/migrate.c in > migrate_page_move_mapping(): it is calling radix_tree_lookup_slot() > without first taking an rcu_read_lock(). > > It was triggered by a memory allocation out of ext4_fill_super(), > which then triggered a memory compaction/migration, but I don't > believe it's otherwise related to the ext4 code. > > Over to the linux-mm folks for confirmation... I think it's no problem. That's because migration always holds lock_page on the file page. So the page couldn't remove from radix. -- 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/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>