The patch titled mm: grab rcu read lock in move_pages() has been added to the -mm tree. Its filename is mm-grab-rcu-read-lock-in-move_pages.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: mm: grab rcu read lock in move_pages() From: Greg Thelen <gthelen@xxxxxxxxxx> The move_pages() usage of find_task_by_vpid() requires rcu_read_lock() to prevent free_pid() from reclaiming the pid. Without this patch, RCU warnings are printed in v2.6.38-rc4 move_pages() with: CONFIG_LOCKUP_DETECTOR=y CONFIG_PREEMPT=y CONFIG_LOCKDEP=y CONFIG_PROVE_LOCKING=y CONFIG_PROVE_RCU=y Previously, migrate_pages() went through a similar transformation replacing usage of tasklist_lock with rcu read lock: commit 55cfaa3cbdd29c4919ecb5fb8965c310f357e48c Author: Zeng Zhaoming <zengzm.kernel@xxxxxxxxx> Date: Thu Dec 2 14:31:13 2010 -0800 mm/mempolicy.c: add rcu read lock to protect pid structure commit 1e50df39f6e2c3a4a3394df62baa8a213df16c54 Author: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Date: Thu Jan 13 15:46:14 2011 -0800 mempolicy: remove tasklist_lock from migrate_pages Signed-off-by: Greg Thelen <gthelen@xxxxxxxxxx> Cc: Mel Gorman <mel@xxxxxxxxx> Cc: Minchan Kim <minchan.kim@xxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Zeng Zhaoming <zengzm.kernel@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/migrate.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff -puN mm/migrate.c~mm-grab-rcu-read-lock-in-move_pages mm/migrate.c --- a/mm/migrate.c~mm-grab-rcu-read-lock-in-move_pages +++ a/mm/migrate.c @@ -1287,14 +1287,14 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid, return -EPERM; /* Find the mm_struct */ - read_lock(&tasklist_lock); + rcu_read_lock(); task = pid ? find_task_by_vpid(pid) : current; if (!task) { - read_unlock(&tasklist_lock); + rcu_read_unlock(); return -ESRCH; } mm = get_task_mm(task); - read_unlock(&tasklist_lock); + rcu_read_unlock(); if (!mm) return -EINVAL; _ Patches currently in -mm which might be from gthelen@xxxxxxxxxx are mm-grab-rcu-read-lock-in-move_pages.patch memcg-res_counter_read_u64-fix-potential-races-on-32-bit-machines.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html