The patch titled ioprio: rcu_read_lock/unlock protect find_task_by_vpid call (V2) has been added to the -mm tree. Its filename is ioprio-rcu_read_lock-unlock-protect-find_task_by_vpid-call-v2.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: ioprio: rcu_read_lock/unlock protect find_task_by_vpid call (V2) From: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Commit 4221a9918e38b7494cee341dda7b7b4bb8c04bde ("Add RCU check for find_task_by_vpid()") introduced rcu_lockdep_assert to find_task_by_pid_ns. Assertion failed in sys_ioprio_get. The patch is fixing assertion failure in ioprio_set as well. kernel/pid.c:419 invoked rcu_dereference_check() without protection! stack backtrace: Pid: 4254, comm: iotop Not tainted Call Trace: [<ffffffff810656f2>] lockdep_rcu_dereference+0xaa/0xb2 [<ffffffff81053c67>] find_task_by_pid_ns+0x4f/0x68 [<ffffffff81053c9d>] find_task_by_vpid+0x1d/0x1f [<ffffffff811104e2>] sys_ioprio_get+0x50/0x2da [<ffffffff81002182>] system_call_fastpath+0x16/0x1b Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> Cc: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/ioprio.c | 4 ++++ 1 file changed, 4 insertions(+) diff -puN fs/ioprio.c~ioprio-rcu_read_lock-unlock-protect-find_task_by_vpid-call-v2 fs/ioprio.c --- a/fs/ioprio.c~ioprio-rcu_read_lock-unlock-protect-find_task_by_vpid-call-v2 +++ a/fs/ioprio.c @@ -106,12 +106,14 @@ SYSCALL_DEFINE3(ioprio_set, int, which, rcu_read_lock(); switch (which) { case IOPRIO_WHO_PROCESS: + rcu_read_lock(); if (!who) p = current; else p = find_task_by_vpid(who); if (p) ret = set_task_ioprio(p, ioprio); + rcu_read_unlock(); break; case IOPRIO_WHO_PGRP: if (!who) @@ -195,12 +197,14 @@ SYSCALL_DEFINE2(ioprio_get, int, which, rcu_read_lock(); switch (which) { case IOPRIO_WHO_PROCESS: + rcu_read_lock(); if (!who) p = current; else p = find_task_by_vpid(who); if (p) ret = get_task_ioprio(p); + rcu_read_unlock(); break; case IOPRIO_WHO_PGRP: if (!who) _ Patches currently in -mm which might be from sergey.senozhatsky@xxxxxxxxx are linux-next.patch ioprio-rcu_read_lock-unlock-protect-find_task_by_vpid-call-v2.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